#vacuumforming

Most procurement specs don’t capture it. They list density, ILD, FST rating, lead time. None of those tell you whether the supplier will catch your engineer’s spec mistake before tooling cuts steel.

That’s where the real cost lives.

We’ve been a Polyurethane Foam Supplier since 1971. The question we hear most from new customers isn’t about price. It’s some version of: “Why didn’t anyone tell me that grade wouldn’t work?”

Foam grade isn’t a commodity decision

Polyurethane foam is a family, not a single material. Open cell or closed cell. Ester or ether polyol. Conventional foam, high-resilience, viscoelastic, integral skin, reticulated. Each one behaves differently under load, in heat, around solvents.

Pick the wrong one and the part either fails the test, fails in the field, or quietly costs 30% more than it needed to. We’ve seen all three.

A Polyurethane Foam Supplier worth working with talks about grade selection at quote stage. Not after first article. If they don’t ask what the part is doing — temperature range, load profile, chemical exposure, regulatory environment — you’re talking to a distributor, not a supplier.

In-house conversion changes the math

Here’s the math that matters. A program with three vendors (raw stock, cutting, finishing) carries three queue times, three tooling reviews, three QA hand-offs, three sets of certification documentation. Consolidate to one supplier and you cut about half the lead time and most of the certification overhead.

For aerospace and medical work this is enormous. Every additional vendor expands your audit footprint. Every additional process owner is one more place a corrective action can fall through.

Our shop runs Custom Foam Fabrication, vacuum forming, painting, and assembly under one roof. That’s not a marketing line. It’s the only way we’ve found to compress lead time without burning weekend overtime.

Certification logos vs. certification substance

A lot of suppliers list ISO and AS9100 logos on their website. Fewer can show you a recent internal audit finding and explain how they closed it.

If you’re qualifying a new Polyurethane Foam Supplier, ask for these three things:

● Their last AS9100 surveillance report (not the certificate, the actual report)

● A recent first article inspection package

● Their NCM log for the last quarter

The supplier who can produce all three within a day takes their quality system seriously. The one who needs a week to find them, doesn’t.

What different industries actually need

Aerospace: FST compliance to FAR 25.853. Documented lot traceability. Foam grades that survive cabin temperature swings.

Medical: biocompatibility (ISO 10993 categories). Latex-free. Cleanroom-handled where required.

Automotive: NVH performance. OEM color match. IATF/TS quality discipline.

Electronics: ESD-safe and conductive grades. CNC-precise cavities for instrument transit. FOD control.

Amusement and entertainment: durable foam that takes paint well, holds detail through years of touch.

Foam Products that work across these industries develop cross-applicable disciplines. Aerospace traceability tightens medical work. Automotive volume drives faster tooling cycles. Entertainment finish work informs paint quality.

Five questions that surface real capability fast

When you’re qualifying a Polyurethane Foam Supplier, these usually separate signal from marketing:

● What’s actually done in-house versus subcontracted? Get specifics. “Painting” isn’t an answer; “primer plus 2K topcoat in our own booth, ESD spray for electronics on the other line” is.

● Show me a quote from a similar program. How was foam grade rationale documented?

● What was your last late delivery and what changed because of it?

● Walk me through your incoming material inspection.

● Who at your shop will I actually be talking to once the PO drops?

Answer five honestly and you know whether to send the RFQ.

Thermoformed trays are also called plastic inner trays. Thermoformed trays are plastics that use thermoforming manufacturing process to make hard plastic sheets into specific grooves. The products are placed in the grooves to protect and beautify the products.

Thermoformed trays also have material handling trays. Thermoformed trays are mostly used for convenience.

Compared with other types of packaging on the market, thermoformed plastic trays are hygienic, environmentally friendly, low-cost, and easy to clean.

They are widely used in electronics, pharmaceuticals, food and other industries to play the role of anti-static, foil, shockproof, separation and fixation.

The types of thermoforming trays mainly include plastic drip trays, plastic shipping trays, disposable shipping trays, foam trays, automation trays recycling thermoformed trays, vacuum forming trays, etc. This article will take you to learn more about thermoforming plastic trays.

Thermoforming Trays Materials

The raw materials of thermoformed products are only plastic sheet, and the thickness of the film generally does not exceed 1.5mm. Commonly used sheets include: PVC, PET, PP, PS and based on this, flocking sheets, gold-plated sheets and anti-static sheets.

Environmental advantages of thermoformed trays

Reusable

Most thermoformed trays are made of environmentally friendly plastic materials, which greatly reduces environmental pollution and resource consumption, and meets the environmental protection requirements of modern society.

Reusable trays are used frequently in corporate logistics, so recycling within the company is a common method.

Enterprises can reuse used recyclable vacuum forming trays after cleaning, disinfecting and other procedures. In addition to recycling within the company, it is also a common method to send recyclable thermoformed trays to other factories for recycling.

Enterprises can classify and package used recyclable thermoformed trays and send them to other factories that have cooperative relationships with the enterprise for recycling.

Environmentally Friendly

Recyclable thermoformed trays are made of degradable materials, which will not cause pollution to the environment and comply with the environmental protection requirements of modern society.

Save Costs

Recyclable thermoformed trays adopt a reusable design, which can reduce logistics costs and save enterprises' operating costs.

High Reliability

Recyclable thermoformed trays have strong carrying capacity, light weight and good durability, which can meet the logistics needs of enterprises and bring greater value to enterprises.

Twin Sheet Thermoformed Trays

The twin sheet thermoformed tray consists of a top cover and bottom bracket with a lock and a foldable enclosure to form a complete set of combined plastic trays. The top cover and bottom bracket are made of HDPE.

It is formed using a one-time twin sheet thermoforming process. The middle hoarding can be made of PP (polypropylene resin) plastic hollow board or seven-layer corrugated cardboard to make a foldable hoarding.

The entire series is designed to be recycled, and the top cover and bottom bracket can be recycled for up to ten years.

Plastic hoardings and corrugated paper hoardings can also be recycled multiple times and replaced.

This design can greatly reduce customers' logistics operations and warehousing costs.

The middle panels of the tray are designed to be foldable, and the top cover and bottom bracket can be embedded or stacked, which can save 50% of storage space compared with traditional packaging.

The thermoformed top cover and bottom bracket are both thermoformed from two HDPE sheets at one time, which is strong and durable.

Is the assembly or disassembly of thermoformed trays extremely convenient?

One person can complete the disassembly or assembly in a few minutes without using any tools. The top cover and bottom bracket are each designed with four quick locks, which can lock the hoarding, so there is no need to bundle it, saving packing materials and labor costs.

Constraints on the Development of Thermoformed Trays

The Usage Method is Backward

The advantages of thermoforming trays cannot be fully utilized. The thermoformed tray itself is a unitized logistics device born to cooperate with efficient logistics.

It can be said that the tray is the connection point throughout all aspects of the modern logistics system.

However, in our actual use, due to the inconsistent specifications, trays cannot be circulated and used in the logistics operation chain, and are only limited to within the enterprise.

The Cost of the Circulation Process is Too High

From the survey, it can be found that the vast majority of companies' PVC pressure forming trays are recycled within the company, so that the company's products undergo manual handling and loading and unloading many times, which greatly reduces work efficiency and correspondingly increases the circulation cost of the products, thus Reducing the competitiveness of the product in the market.

Difficult to Conform to International Standards

Due to the inconsistent specifications and standards of PVC thermoformed trays, the use of trays in various countries cannot match international transportation equipment (such as international containers, etc.).

In order to adapt to relevant international transportation tools, companies have to order trays from tray manufacturers that are inconsistent with the company's turnover specifications, thereby increasing the company's export costs and reducing the international competitiveness of its products.

Application of Thermoformed Trays

There are many types of thermoformed trays. Trays are one of the types of thermoforming in the thermoforming industry. This type of tray has a strong bearing capacity.

According to the shape, structure and weight of the item, thermoforming tray is suitable for withstanding the force. There are also many thicknesses of materials used.

The choice depends on the packaging material needs of the packaged items. This type of thermoformed tray is commonly used in the electronics industry, toy industry, stationery industry, technology product industry, cosmetics industry, health care products industry, etc.

In terms of use, the commonly used materials for this type of trays include PVC and PS hard film. Generally, transparent thermoformed trays are more commonly used in thermoformed packaging. Other colors can be selected according to individual needs.

Thermoformed trays are widely used in food, medicine, electronics, chemicals, logistics and other industries. They have the advantages of light weight, beautiful appearance, moisture-proof, shock-proof, and anti-oxidation.

Compared with traditional wooden trays, thermoformed trays are more hygienic, durable, easy to clean and disinfect, and meet the environmental protection and hygiene requirements of modern enterprises.

How to Choose High-Quality Thermoformed Trays

When choosing a high-quality thermoformed tray, you need to comprehensively consider the actual needs and choose the tray that suits you.

At the same time, it is also very important to choose a regular thermoformed tray manufacturer.

Thermoforming Trays Material

Thermoformed trays are typically made from polyethylene (PE) or polypropylene (PP), both of which are highly durable and recyclable. You can choose according to your specific needs when choosing.

Tray Size and Shape

The size and shape of thermoformed trays should be determined based on the cargo required to be loaded.

The size of the tray should be slightly larger than the size of the goods so that the goods can be placed stably on the tray.

Tray Load-Bearing Capacity

The load-bearing capacity of a thermoforming tray is determined by its material and construction. When selecting a tray, you should consider whether its load-bearing capacity can meet the requirements of the goods.

Tray Price

The price of thermoformed trays varies based on factors such as material, size, shape, and load-bearing capacity.

When choosing a tray, you should consider its cost performance and choose a tray that suits you.

Cases

Automobile Industry

Twin sheet thermoforming: dedicated thermoforming trays for the automotive industry

For Tier 1 automotive suppliers, in the process of transporting those large mechanical parts or bulk small parts from their factories to the OEM automotive assembly line, they usually need to use large customized trays in order to stack the goods in an orderly manner. Avoid collision damage.

For example, the custom-made tray below is very suitable for transporting those precision mechanical parts to the OEM's automobile assembly line. The forminging process includes the following processes:

First, two sheets are placed at designated positions on the orifice plate of the thermoforming machine, and then the clamp automatically lowers and a moving intermediate frame brings in the other two sheets.

Two sets of halogen lamp heaters will quickly heat the four sheets according to the heating path set by the computer. Precise temperature control is achieved through a fine-hole grid of photocells.

During this process, it is necessary to ensure that the sheet is flat when heated.

Then, the mold is closed. Under the action of a clamping force of hundreds of thousands of Newtons, the two sheets are combined into a strong structural panel.

By introducing a certain pressure of air between the two layers of sheets, the sheets and the mold can fit more closely, and it can also have a certain cooling effect.

After the mold has cooled, immediately open the moving middle frame and remove the two formed trays.

Finally, the robot takes the formed product out of the mold, and then puts the next set of four preheated sheets into the mold to start the next production cycle. One product can be produced every 5 minutes.

Chemical Industry

For the chemical industry, the issue of safe transportation of goods is very important. Thermoformed trays solve this problem with their natural advantages and improve the safety and stability of cargo transportation. The advantages of thermoformed trays include the following:

1. Durability

Thermoformed plastic trays are more sturdy and durable because they can not only bear a large weight but also avoid corrosion by chemical products, so they are widely used in the chemical industry.

2. Lightweight

The main materials of thermoformed trays are thermoplastics, so they are lighter. Whether in cargo transportation, stacking, or storage, labor intensity is greatly reduced. At the same time, it also brings great convenience to the logistics industry.

3. Environmentally friendly materials

Compared with traditional wood or paper materials, thermoformed trays are a more environmentally friendly material. Using thermoformed trays reduces logging and felling of trees and reduces the impact on the environment.

4. Recyclability

The thermoformed plastic tray is made of ultra-high molecular weight polyethylene and can be recycled. Used thermoforming trays can be recycled into new trays, reducing the waste of resources and better protecting the environment.

5. Hygiene

Product transportation in the chemical industry often requires attention to the hygienic environment. The surface of the thermoformed tray has almost no pores and gaps, so it will not accumulate bacteria and viruses, and is highly safe. It is also easy to keep clean and has a long service life.

Conclusion

As an important logistics packaging tool, thermoformed trays play an important role in logistics, manufacturing and retail industries. Its lightweight, durable, easy to clean and environmentally friendly features make it an ideal alternative to traditional wooden and metal trays.

With the continuous emergence of new materials and new technologies, multi-layer heavy gauge thermoforming is used in the field of hospital medical equipment shell molding and manufacturing, opening a new chapter in structured products for hospital medical equipment shells.

To this end, it is necessary to explore the relevant elements of heavy gauge thermoforming products for hospital medical equipment casings, consider the optimization path of the thick gauge thermoforming process for medical equipment casings, and improve the quality of hospital medical equipment casing products.

As a plastic processing technology, the main principle of pressure forming is to heat a flat hard plastic sheet to soften it, then use vacuum to adsorb it to the surface of the mold, and then cool it into shape. It is widely used in plastic packaging industry, pharmaceutical packaging sectors, healthcare sector, medical device packaging trays, food packaging industries, pharmaceutical industry, advertising, automotive industry decoration and other industries.

After a whole product is produced, it must be separated into individual small products, and then there will be some leftover edges of the product. Commonly used materials in blister packaging factories include PP, PET, PVC, PE, etc. As a sterile barrier system, medical packaging blister boxes are accepted by more and more medical devices, and PETG material used in medical applications is favored due to its strong. The market growth is significantly.

Ⅰ. Analysis of Design Elements of Medical Equipment Shells

Geometry and Accuracy

The geometric dimensions of the thermoformed shell include: the dimensions from the cutting surface to the molding surface of the thermoformed product, and the dimensions from the cutting surface to the cutting surface, which are directly related to the plate thickness, material properties, and molding process.

Draft Angle

The thermoforming mold consists of a concave mold and a convex mold with different demoulding angles. Generally speaking, the demoulding angle of the concave mold is 0.5°-1°, and the demoulding angle of the convex mold is 2°-5°.

Shell Rounded Corners

The thermoformed shell should be designed with as large rounded corners as possible, and should not be designed with sharp corners and should be chamfered to ensure that the stress of the thermoformed shell product is appropriate.

Aspect Ratio

The width-to-depth ratio of thermoformed products for medical equipment shells is an important indicator to measure the ease of thermoforming. It represents the ratio of the minimum width to depth of the product. The larger the value, the easier it is to form the thin gauge thermoformed plastics product. The smaller the value, the easier it is to form the thermoformed product. It shows that the thermoformed products are more difficult to form.

Ⅱ. Defects

1. Partial Molding of the Product is Insufficient.

The main causes of defects that lead to insufficient local molding of thermoformed shell thick plate products are:

The plasticity of the board itself is poor. There is insufficient vacuum between the sheet and the mold. The sheet has stretched too much. The mold temperature is low, etc.

2. Product Surface Color Defects.

The main causes of product surface color defects include:

Insufficient heating. Overheating. The mold heating temperature is not high.

3. Product Flow Mark Defects.

The main causes of flow mark defects in products include:

The temperature of the mold and plate is not high. Poor mold temperature control. There is a deviation in the molding process.

4. Product Wrinkle Defects.

The main causes of wrinkle defects in products include: The board sags too much. The plate heating time is too long. The molding angle of the mold is too large.

5. Product Surface Flatness is Insufficient.

The main causes of uneven surface defects on products are as follows:

Insufficient cleanliness of the sheet or mold. The mold vacuum hole is too large. The mold does not have enough vacuum holes. There is a lamellar structure on the mold.

Ⅲ. How to Optimize the Production of Medical Device Shells

Optimization of Product Structure

The shell of hospital medical equipment has a large volume and surface area, so it can be designed in a curved shape to maintain the external beauty of the product structure and better avoid the defects of the thermoforming manufacturing process. The optimization of its structure mainly includes the following aspects:

1. Optimize the depth of the product.

Since there are many products with large barrel depths in hospital medical equipment, this brings great challenges to medical device manufacturers. In order to optimize the product molding effect, concave molding and punch-assisted pressing can be used to make the product sheet The material is heated between the upper and lower molds and a small amount of air is sucked out of the punch and the sheet, so that the sheet is adsorbed on the punch, and then the punch is gradually pressed down so that the sheet is completely adsorbed on the concave mold, and finally demoulded. Through this concave and convex mold-assisted molding method, the draft angle of the equipment shell product can be increased and the width-to-depth ratio of the shell product can be reduced.

2. Optimize the rounding of corners.

Based on the actual requirements of assembly, the corner rounding can be optimized at the junction of medical equipment shell products.

3. Adopt assembly bonding.

For thermoformed shells of hospital medical equipment, assembly bonding can be used instead of undercut designs. Double-layer thermoforming technology is used to replace the optimized process of single-layer thermoforming plate bonding to enhance the strength of the shell product.

Optimization of Process Parameters

Since the materials for hospital medical equipment shells are mainly ABS and ABS/PC, and assembly materials such as PC, HIPS, PET, and PP are used, it is necessary to analyze and optimize the process parameters of these different materials, including the following:

1. Sheet drying time.

This is the shrinkage characteristic parameter of the thermoformed sheet in the dry state, which is directly related to and affects the thermoforming of thick plates for medical equipment shells. When the drying times of different materials are: HDPE is 8 hours, PE is 6 hours, ABS is 8 hours, PC is 6 hours, and ABS/PC is 8 hours, it indicates that the performance of the medical equipment shell thick plate thermoforming product is relatively Stablize.

2. Thermoforming temperature. This is mainly analyzed and optimized from the two aspects of sheet heating temperature and pressure forming mold temperature. Among them: double-sided heating is usually used to heat the plastic sheet, and different molding temperatures are set according to different shapes of products. , making the product consistent with the design requirements. The temperature of the thermoforming mold should be kept appropriate and should not be too high or too low. If the mold temperature is too high, the product will adhere to the mold, causing the product to demould and deform. If the mold temperature is too low, the plate will be deformed. Improper molding may cause defects such as black spots, wrinkles, and cracks in the product. Generally speaking, when the medical equipment shell is thermoformed, the mold temperature is controlled at: HDPE is 50°C, PE is 50°C, PVC is 50°C, ABS is 70-80°C, PC is 120°C, and ABS/PC is 110°C. , indicating that the temperature of the thermoforming mold is appropriate.

Optimization of Mold Design

1. Optimize high-pressure thermoforming mold.

The high-pressure frame thermoforming mold structure can be used to fully form the thick plate thermoforming products of medical equipment shells.

2. Add upper mold to assist molding.

You can add an upper mold to assist in molding to produce cylindrical medical device packaging with large depth and complex shapes to avoid defects such as surface breakage or wrinkles on the surface of thermoformed products.

3. Add mold core-pulling structure.

By adding hinges, bonding blocks and cylinders to the design, the demoulding of thermoformed products can be better assisted.

Raw Material Selection

The selection of raw materials is the basis for ensuring quality. From particles to thermoformed finished products, its requirements are much higher than those of food grade and industrial grade. The material selection of medical-grade vacuum forming boxes must meet ROHS requirements, and meet the requirements of IS010993 "Biological Evaluation of Medical Devices" and ISO11607 "Packaging of Terminal Sterilized Medical Devices" to achieve a complete sterile barrier system and microbial barrier function.

At present, there are many categories of food packaging materials produced in our country, with varying degrees of good and bad, and there are many hidden safety hazards. In particular, industrial PVC replaces PETG (material characteristics, usually medical blue), RPET (a recycled PET material) replaces APET, etc. After high-temperature molding and sterilization, a large amount of harmful substances will be precipitated, including pain-causing substances. , causing the device that was originally used to save lives and heal the wounded to eventually become a "killing" weapon. Therefore, we must choose materials carefully. At present, the main medical PETG include American Eastman 6763 and Korean SKS2008.

Thermoformed Box Structural Design

Before design and development, comprehensive factors such as demand for thermoformed plastics, forecast period, raw material selection, packaged equipment, sterilization methods, and clean opening by medical staff should be fully considered. And ensure the ability of sterilized medical device packaging to maintain sterility levels during the validity period. Therefore, details such as the design of edge banding width, hand tearing position, buckling method, etc. all need to be considered in the design stage.

Thermoforming Mold Selection

Medical thermoforming boxes use aluminum alloy molds. There are many kinds of aluminum materials. However, in terms of overall mold processing accuracy and various performance, 6061 is a better aluminum material. The aluminum material is processed into a mold by CNC. Since the inner core is aluminum, it is easy to achieve thermal balance. Cold water flows around it, which allows the mold to cool down quickly and improves the production efficiency of the vacuum forming box. Because the inner core is aluminum, it is easy to achieve thermal balance and cold water flows around it. Let the mold cool down quickly, increase the speed of goods production, and increase the smoothness of the thermoformed box. Because the cost of aluminum molds is high and the general service life is long, Martin Medical Packaging promises customers that the aluminum molds can be used for 10 years and can be produced repeatedly. can maintain high accuracy. There are many master molds on the thermoformed plastics market made of gypsum powder with a layer of copper on the outer electroplating surface. Not to mention the accuracy and appearance of the finished product, the cleanliness cannot meet the requirements of medical device packaging. The quality of the mold making of the thermoformed box directly affects the details of the finished thermoformed box, so it is recommended to choose carefully.

Conclusion

Thermoforming is a plastic processing technology. Different from other plastic processes, the main principle is to heat a hard plastic flat sheet to soften it, then use vacuum adsorption to adsorb the softened sheet to the surface of the mold, and then form it after cooling. Thermoforming is widely used in plastic packaging, lighting, advertising, decoration and other industries.

With the continuous development of science and technology, the manufacturing industry is also constantly innovating and progressing. Among them, thermoforming process, as an emerging manufacturing technology, is gradually becoming a new trend in future manufacturing industry.

There are several thermoforming methods used in actual production, and the most basic ones are six: differential pressure forming, overmolding, plunger-assisted molding, suction molding, countermolding, and twin sheet forming.

Thermoforming is divided into heavy gauge thermoforming and thin gauge thermoforming according to the thickness of the sheet. In this article, we will focus on heavy gauge thermoforming.

What is Heavy Gauge Thermoforming

Heavy gauge thermoforming, also known as thick sheet vacuum forming, refers to a technology where the thickness of the raw materials used exceeds 2mm and cannot be formed on a fully automatic machine. Semi-automatic machining and production technology dedicated to thick sheets must be used.

Heavy gauge thermoforming machine is a key process equipment for producing thermoformed plastic parts through vacuum forming manufacturing process using plastic sheets as raw materials. It uses thermoplastic material sheets as raw materials, is heated to the softening temperature in an oven, and then uses the vacuum negative pressure between the plastic sheet and the thermoforming mold to adsorb the plastic sheet in the thermoplastic state to the surface of the thermoforming mold and then cool it for molding.

Heavy Gauge Thermoforming Materials

The main materials for thick gauge thermoforming include: various colors of ABS, acrylic, PETG, PVC, PC, PP, PE, PS, etc. and various modified plastic plain sheets, textured sheets, and transparent sheets.

Application of Heavu Gauge Thermoforming

Heavy gauge thermoforming can be used for product design and manufacturing of rear projection TV back covers, displays, medical equipment, textile machinery, automotive accessories, and product design and manufacturing in precision electronics, medical equipment, and cosmetics industries.

Heavy gauge thermoforming products mainly include refrigerator liner thermoforming, PS thermoforming, ABS thermoforming, thick sheet thermoforming, thick sheet thermoforming, PMMA thermoforming, etc., which are widely used in medical equipment, food equipment, instrument casings, and electrical appliances. Shells, car body sheaths, pet trays, advertising light boxes, lighting, refrigerator industry, air conditioning industry and home appliance accessories, etc.

Heavy gauge thermoforming products can not only replace injection molding, saving expensive injection mold costs, but also replace traditional manual production. They have the advantages of advanced production technology, fast speed, and reliable quality.

Advantages of Heavy Gauge Thermoforming

It saves raw and auxiliary materials, is light in weight, easy to transport, has good sealing performance, and meets the requirements of environmentally friendly green packaging.

It can pack any special-shaped products, and no additional buffering materials are needed for packaging.

The packaged products are transparent and visible, beautiful in appearance, easy to sell, and suitable for mechanized and automated packaging, which facilitates modern management, saves manpower, and improves efficiency.

Heavy Gauge Thermoforming Machine Components

Heavy gauge thermoforming machines generally consist of sheets positioning system, thermoforming mold positioning system, frame system, heating system, cooling system and electrical control system.

1. The sheets positioning system generally consists of material pressing frame, power cylinder or an oil cylinder, and balance synchronization mechanism. Its function is to tighten the positioning of plastic sheets. The press frame of the walking frame heating method has an upper and lower structure, and is equipped with a transverse locking mechanism to ensure that the press frame can be tightly sealed with the plate backing plate. The frame can be adjusted according to the size of the mold, either manually or automatically.

2. The thermoforming mold positioning system generally consists of upper and lower mold tables, upper and lower mold cylinders or oil cylinders, and synchronization mechanisms. Its function is to tighten the positioning of the thermoforming mold and connect the mold to the vacuum pipeline. There are two positioning methods: manual screw locking or pneumatic automatic locking. The synchronization mechanism can ensure that the upper and lower molds rise and fall simultaneously to ensure vacuum forming accuracy.

3. The frame system generally consists of profile frame, sealed box, and protective door. Protective doors are divided into automatic and manual.

4. The heating system generally consists of heating bricks or heating tubes, oven frames, and power cylinders or motors.

5. The cooling system generally consists of air and water pipes and spray heads.

6. Electrical system: The electrical control system cooperates with the pneumatic or hydraulic system to realize the process requirements (temperature, speed, time) and various program actions of the thermoforming machine. It is mainly composed of PLC and touch screen, contactors, electronic components, temperature regulating instruments, solenoid valves, sensors, etc. There are generally three control methods, manual, automatic and adjustment.

Heavy Gauge Thermoforming Production Process

The principle of heavy gauge thermoforming is similar to that of light gauge thermoforming. The positioned sheet is heated to a softened state in an oven, and the vacuum forming mold forms a closed space around it to instantly remove the air from the mold cavity and tightly cover the sheet. The process of cooling and shaping the mold surface to obtain the finished product.

Thermoforming is a cyclic process, and each cycle mainly includes: loading - heating and softening - backflushing and pre-drawing - pressure forming - cooling and shaping - demoulding and picking. After taking out the plastic parts, place the plate again (can be received or automatically) and proceed to the next cycle.

1. Mold making and processing: Different customers have corresponding specifications for the product, so plastic molds must be made before production. In this case, the mold is made from plaster of a plastic mold, and the mold is produced using plastic. The lower cost is the plaster mold, followed by the electroplated copper mold, while the aluminum mold is more expensive. When the mold is made, let it dry naturally or dry it, and then treat it according to the specific conditions of the product surface. to

2. When the mold is completely dry, the mold should be placed on the upper iron plate of the vacuum chamber, and then according to the size of the mold, load the mold into the applicable size and then put the paper into the hot wood cabinet to fix it and process it.  

3. Fix the plastic sheet on the mold with fixing clips, heat both ends of the plastic sheet until it becomes soft, and then use a vacuum pump to remove the air between the material and the mold, allowing the softened plastic sheet to be adsorbed on the mold and cool. Then blow air in the opposite direction to release the product from the mold. ​

4. Finishing: The finished product is trimmed and integrated into a product that can be packaged for sale. Thin gauge plastic thermoforming is generally used in food packaging, pharmaceutical packaging, cosmetic packaging and other industries. Product thickness 10-100 silk. Heavy gauge vacuum forming is mainly used in automobile, hardware, electric vehicle and other industries, and the product thickness is 1-10mm or even thicker.

Thermoforming & Injection Molding & Blow Molding

Injection molding

Injection molding is to melt the plastic raw materials, then put them into the mold under high pressure through an injection molding machine, and then cool them into shape.

Blow Molding

Blow molding is a rapidly growing plastic processing method. The tubular plastic parison obtained by extrusion or injection molding of thermoplastic resin is placed in a split mold while it is hot (or heated to a softened state). After the mold is closed, compressed air is immediately introduced into the parison to blow the plastic parison. It expands and adheres closely to the inner wall of the mold. After cooling and demoulding, various hollow products are obtained.

Main Difference

1. Thermoforming: It is suitable for products with relatively simple structure, single-sided molding and small quantity. Molds are very cheap. The mold cost is only 1/20 of that of injection molds. The mold opening time of products of similar complexity is only 1/4 of that of injection molds. However, complex structures cannot be designed and are generally bonded through adapters. It is also similar to the carbon fiber hot pressing process.

2. Injection molding: suitable for large-volume, high-precision products, the mold cost is very high, and complex structures can be designed.

3. Blow molding: mainly used to produce hollow products, such as bottles, cans and other products. The price of the mold is not much different from that of thermoforming molds.

Case

Medical industry

Why heavy gauge thermoforming?

1. The order quantity of medical products is small. Compared with other consumer products, the steel materials with slightly better mold life of general injection molding can be molded one million times. However, it is difficult for general large-scale medical products to reach this level. The plastic mold The price is transferred to a single product, resulting in a very high unit price (applicable to products with a batch size of less than 5,000 and whose appearance level requirements are not particularly high, especially suitable for the casing of robot products).

2. Compared with injection molding, heavy gauge thermoforming has a simple structure and can still meet most of the needs. It has stable performance, satisfactory surface treatment, and can be adapted to silk screen printing (ABS) of various colors.

Conclusion

With the improvement of consumers' own consumption and health awareness, the concreteness and transparency of product information have become the focus of consumers' attention when purchasing products.

Thermoformed packaging has a good sales display effect because the packaged contents are visible. Generally, irregular objects are sealed and protected by using PVC or PET transparent thermoforming, and then the blister and the paper card (paper) coated with thermoforming oil are bonded together by hot pressing to form a complete, regular and transparent object package style. The function of the blister card is to seal and fix the object, and the paper card supports the object.

At the same time, graphic information must be printed on the paper card. The thermoforming oil will firmly bond the blister card and paper card together under heated conditions to ensure the integrity of the packaging during storage and transportation.

At present, the processes, materials and equipment of thermoforming packaging are relatively mature, and related process technologies have been industrialized, such as: batteries, stationery, hardware, toys, personal care, cosmetics, small household appliances, other daily necessities and other product fields. In carton packaging has been widely used.

The quality evaluation indicators of thermoformed products generally include plastic absorption, anti-adhesion, gloss, wear resistance, environmental resistance, high-speed line processability, etc. In the production process, the most prominent problem is that the heat sealing effect of the carton product after molding is not up to standard, that is, the quality problem of poor thermoforming.

The quality requirements are generally: after the product is packaged, the blister card can be torn open under the premise of a drop test at least Open 80% of the paper fiber layer.

In practice, there are many factors that affect the poor thermoformability of products, including: thermoforming quality and stability of paper cards (paper), ink materials, blister card quality, thermoforming oil materials, heat sealing process conditions, etc. Among these conditions The interaction between them directly affects the vacuum forming effect.

Ⅰ. Advantages of Thermoformed Packaging

Thermoformed packaging blister cards are made of transparent materials, with PVC and PET being the most commonly used. At the product terminal, the paper cards are generally hung and placed on the shelf.

The shape of the product is clear at a glance, which is in line with the current consumer consumption patterns. Therefore, this kind of packaged products Usually hung in a prominent position on shopping mall shelves to facilitate sales.

By wrapping irregular products with blister cards, the appearance of special-shaped products can be relatively neat and beautiful, making storage and transportation more convenient, and no additional buffering materials are needed for packaging.

Thermoforming packaging can ensure that the products in the thermoformed blister card are not contaminated by external dust and have a certain barrier effect on water vapor, which not only ensures that the quality of the product is not affected, but also meets the requirements of environmentally friendly green packaging.

It has a certain function of preventing opening and being used at any time, allowing consumers to purchase with more confidence.

Ⅱ. Principle of Thermoforming and Heat Sealing Packaging Process

The blister card and the paper card coated with thermoforming oil are heated through a customized mold using electric heating or high frequency. The softened blister card and the melted pressure forming oil are heated under pressure.

After solid fusion and cooling, the blister card, thermoforming oil, and paper card form one body to complete the thermoforming packaging process.

During thermoforming heat sealing and encapsulation, the thermoforming oil is heated until it softens and becomes viscous (at room temperature, thermoforming oil, as a special varnish coating, has the characteristics of a general varnish coating, that is, it has a certain gloss and wear resistance. properties), if any material is below its softening point, fusion cannot occur effectively and the seal becomes very poor.

Ⅲ. Factors Affecting Thermoforming Effect

There are many factors that affect the thermoforming effect. Usually, during the product sampling process, companies will use the empirical elimination method to find the factors that cause the poor thermoforming effect of the product.

The main factors that affect the thermoforming effect include: influence of materials (paper, ink, thermoforming oil), improper process parameters and methods (temperature, pressure, thermoforming time), and different equipment heating methods.

The Influence of Paper

The different properties of paper (paper card) materials directly affect the thermoforming effect. Factors including: paper tightness, paper fiber, surface strength, surface flatness, smoothness, sizing degree, etc., will all affect the thermoforming effect. Combined with the actual production, the proofing process was tested and analyzed, and the following empirical conclusions were drawn:

Paper absorbency effects. The penetration ability of ink or thermoforming oil into the paper is very important. The thermoforming effect of mechanical wood pulp with low tightness and fluffy fiber inside the paper is better.

The thermoforming oil can easily penetrate into the inside of the paper. When the thermoforming oil is completely When dry, the thermoforming effect is very good; otherwise, the thermoforming oil accumulates on the surface of the paper, which is not easy to dry and will easily fall off after thermoforming.

The lower the surface strength and internal bonding strength of the paper, the better the thermoforming effect. It is best to have no internal and surface sizing. However, if the amount of sizing on the paper is too small, the surface strength of the paper will easily decrease, surface peeling will easily occur during the printing process (commonly known as lint and powder loss), and the paper hardness will be poor.

Effect of paper moisture content on thermoformability. If the moisture content of the paper is too high, the surface strength will be reduced and the drying speed will be slow. When the molding oil is overheated, the surface will bubble, resulting in poor thermoforming and poor results. Generally, it is required that the paper should be processed to balance the moisture content, and it is better to dry it.

At the same time, the product generally needs to be left for 8-12 hours after thermoforming before use. On the contrary, it is not good if the paper is too dry and brittle, which may easily cause the thermoforming part to be unstable.

The Influence of Printing Ink

Factors such as different components of printing ink materials, film thickness, compatibility of ink and thermoforming oil, ink drying speed, etc., directly affect the thermoforming effect. General requirements:

1. The ink used should be free of silicone wax and oil as much as possible. It has good gloss and smoothness, but the thermoforming oil is not easy to penetrate, and the thermoforming effect will be lower.

2. If the printing ink layer is thin and the viscosity is low, the inside of the ink dries quickly, the thermoforming oil can easily penetrate, and the thermoforming effect is better; the toner particles in the ink component are small and the ink color concentration is high, which is beneficial to the thermoforming effect. .

3. It is difficult to thermoform metal ink, but it can be achieved when the ink layer is thin.

4. The properties of the ink and the thermoforming oil must match, have strong adhesion to each other, and will not produce other chemical reactions.

5. Some resin materials in the ink components will have high hardness after curing (such as UV ink), resulting in unstable thermoforming effects. Generally, printing inks with resin components that do not have high hardness after curing are selected.

The Influence of Thermoforming Oil

Thermoforming oil is a polymer material with many types, which can be classified according to applicable materials, such as PET thermoforming oil, PVC thermoforming oil, gold and silver card thermoforming oil, cardboard thermoforming oil, etc. Its main components are resins (such as polyurethane, acrylic), additives (such as anti-aging agents, diluents, etc.).

According to different properties, it is divided into water-based thermoforming oil, oil-based thermoforming oil, polishing thermoforming oil, wear-resistant thermoforming oil, powerful thermoforming oil, etc.

General requirements: During the coating process, the coating amount should be controlled to ensure the leveling, gloss, penetration, and dryness of the film surface. The thermoforming process mainly controls temperature, pressure, and time to ensure that the thermoforming is firm.

The Influence of Blister Card

Blister card is a transparent material used for thermoforming packaging (generally PET polyester, PVC polyvinyl chloride, PS polystyrene and other materials), which is heated by paper that has been coated with thermoforming oil. Press, shrink and bond together to form a complete, regular and transparent packaging product.

The most commonly used A-PET (Amorphous Polyethylene Terephthalate) thermoforming material is a kind of PET material. It is a thermoplastic environmentally friendly plastic product. It is stable at room temperature. It shrinks when heated (above the glass transition temperature of the material) and in one direction.

A thermal shrinkage of more than 50% is ideal. Compared with PVC materials, APET materials have obvious advantages: light specific gravity (low density), high strength, good folding resistance, high transparency, strong impact resistance, no crystal points, easy to decompose and environmentally friendly.

General requirements in actual production:

1. If APET is heated beyond the crystallization temperature and the heating time is too long, PET may be converted into a crystalline state and become white, which will lead to a significant reduction in sealing quality in the crystalline state and poor thermoformability.

2. The heat sealing temperature must be controlled enough to soften the thermoforming oil layer and PET vacuum forming, but not to convert PET into a crystalline state.

3. In actual production, if the material type of the thermoformed cover is changed, such as changing the PET model or changing PVC to PET, a comprehensive test and evaluation must be conducted first.

4. Combined with the actual production requirements, the design parameter requirements for the thermoformed cover:

The thickness must be greater than 0.15mm. The film thickness will be reduced during thermoforming. Pay attention to incoming material inspection. •Effective thermoforming area width >5mm.

The deformation of the thermoforming cover will affect the thermoforming effect.

If the release oil used in manufacturing the thermoformed cover remains on the surface of the thermoformed cover, it will affect the surface tension of the thermoformed cover, reduce the dyne value, and affect the thermoforming effect.

The Influence of Thermoforming Process Production

The thermoforming process includes: printing and coating thermoforming oil process and thermoforming heat sealing process. Currently, there are three ways to realize the coating process: offline oiling machine, full page oiling, silk screen partial oiling, and offset printing in-line oiling.

Offline coating and thermoforming processes generally require that the product be left for at least 72 hours after printing. After the large dark ink area is completely dry, hot molding oil can be applied to the surface and left for at least 24 hours before the thermoforming process can be carried out.

The current method of oiling the line (usually using water-based thermoforming oil) can shorten the time, but the thermoforming effect is not good. The main control objectives of the oiling process are: appropriate amount of oil (generally about 3-5g/m2, depending on the surface properties of the material and the concentration of the thermoforming oil), and full penetration of the thermoforming oil.

The coating amount must be controlled during the coating process to ensure the leveling, gloss, penetration, dryness, etc. of the film surface. The pressure forming process mainly controls temperature, pressure, time and other conditions to ensure the thermoforming effect.

The Influence of Thermoforming Equipment

There are three types of heating methods for thermoforming packaging equipment: traditional back heating, heating plate surface heating, and high-frequency internal heating. Different heating methods, different temperature control methods, and different heat transfer effects result in different thermoforming oil softening and thermoforming cooling forming effects.

The traditional thermoforming process uses back heating. The heated plate is heated, and heat is transferred to the surface of the thermoforming oil and the thermoforming cover through the back of the paper card to complete the thermoforming process.

The thermoforming temperature is relatively constant and cannot be adjusted quickly; the heat transfer is affected by the thickness of the paper has a great influence. The thicker the paper, the harder it is for the heat to be quickly transferred to the thermoforming cover.

Therefore, sufficient thermoforming pressing time must be given to allow the heat to be fully transferred to the thermoforming cover to ensure the thermoforming effect.

The heating plate thermoforming machine heats the surface of the thermoforming cover and transfers heat to the surface of the thermoforming oil to complete the vacuum forming process. The thermoforming temperature can be quickly adjusted; because the heating plate is in direct contact with the thermoforming cover, when the temperature is too high, the thermoforming cover is extremely susceptible to thermal deformation and it is difficult to transfer heat to the surface of the thermoforming oil (the thinner the thermoforming cover, the easier it is to transfer heat, but the easier it is to deform).

To ensure a good thermoforming effect, you must choose a thermoforming material with an appropriate thickness. Cover and adjust the thermoforming temperature and fusion time.

High-frequency internal heating uses a high-frequency electric field to oscillate the internal molecules of the thermoforming cover and thermoforming oil to generate heat energy to complete the thermoforming process. The temperature can be quickly adjusted.

This heating method has the most stable heat transfer and can adjust the corresponding temperature at will according to the properties of the material. However, because a large current is generated at the moment of fusion and sparks are easily generated, it is not suitable for transferring silver card products to thermoforming.

In practice, since the thermoforming temperature has a greater impact on the thermoforming effect, it is generally recommended to use thermoforming packaging equipment that can quickly adjust the temperature.

Conclusion

This article focuses on analyzing the quality problems of poor thermoformability during the thermoforming process of color box packaging products, and qualitatively analyzes the possible influencing factors from three aspects: materials, process methods, and equipment, which has obvious guiding significance for actual production. In actual work, we must first understand the customer's product requirements, master good problem analysis and solution methods, and be as familiar as possible with the thermoforming process principles, materials, equipment, and production processes in business.

Thermoforming process has developed rapidly in recent years and is now widely used in toys, food, medicine, daily chemicals, electronics, cosmetics and other fields closely related to the lives of the masses. With the increase in population, the demand has also expanded infinitely. It can be seen that in the future, elements will be added to thermoformed products to make them beautiful, such as floral thermoformed boxes, colorful thermoformed boxes, etc. These new words and new things are coming to the forefront.

In today's daily life, with the development of many industries and the expansion of each field, as society progresses and the population increases, the demand for thermoformed products will become larger and larger. They will also become more and more picky about quality, appearance, shape, price, design and other aspects. Therefore, the thermoforming industry will be forced by society to develop.

Common Problems and Principles in Thermoforming Production Process

Blistering

1. The heating temperature is too high, the temperature should be lowered appropriately.

2. The heating speed is too fast, and the heating speed should be slowed down appropriately.

3. If the sheet is too close to the heater, the distance between the two should be appropriately increased.

4. If the sheet becomes damp, the sheet should be pre-dried or preheated. The moisture-proof packaging of the sheet should be unpacked at the processing site.

5. If the sheet is heated unevenly, a heat shielding net should be used to adjust the heating state of the surface of the sheet so that all parts are heated evenly.

6. The sheet type or formula is unreasonable. Other types of sheets should be replaced or the formula should be adjusted.

7. The quality of raw materials, whether they are brand new materials.

8. Whether the mold to be made is a copper mold, an aluminum mold, or a plaster mold, this is related to the mold making itself.

9. Whether there is dust in the production environment, whether the workshop is dust-free, whether the surrounding area of the machine is clean, etc.

Pre-Stretched Bubbles Have Uneven Shapes

1. The sheet is heated unevenly and should be heated slowly or a heat shielding net should be installed.

2. If the sheet is uneven in thickness, it should be replaced with a sheet of uniform thickness.

3. The air pressure distribution is uneven. The air flow should be homogenized to make the air pressure evenly distributed.

4. The air pressure distribution is uneven. The air flow should be homogenized to make the air pressure evenly distributed.

Collapse, Arch or Wrinkle

1. The heater temperature is too high, the heater temperature should be lowered appropriately.

2. The heating speed is too fast, the heating speed should be appropriate or slowed down.

3. If the sheet is too close to the heater, the distance between the two should be appropriately increased.

4. The heating time of the sheet is too long, and the heating time should be shortened appropriately.

5. The melt index of the raw material for processing the sheet is too high, the melt strength is too low, and the sheet sags excessively after being heated during thermoforming. The resin processed sheet should be replaced with a lower melt index.

6. The orientation of the sheet is too small, and the sheet sag excessively after being heated. Sheets with higher orientation should be replaced, and the heating temperature is best controlled within the lowest molding temperature range of the sheet.

7. The stretch ratio in the forming area is too large. A plunger should be used to assist, or the pressure assist, moving speed of the plunger or mold should be appropriately increased.

8. The mold structure design is unreasonable. The mold structure design should be modified. First, use a female mold instead of a male mold. The second is to increase the sharp angle and fillet radius of the product as much as possible. The third is to redesign the miner and boost pressure.

Incomplete Forming or Unclear Surface Pattern

1. The sheet heating time is too short or the heater temperature is too low. The heating time should be appropriately extended or the heating tube temperature should be increased.

2. The heating power of the heater is too small. The heating power of the heater should be appropriately increased.

3. The sheet is heated unevenly, and molding defects always appear repeatedly in the same part. Use a heat shielding net to adjust the heating state of the sheet so that all parts are heated evenly.

4. The clamping frame is not preheated before clamping. The clamping frame should be preheated before clamping.

5. The vacuum hole is blocked and the vacuum degree is low. The vacuum hole should be cleaned and unclogged.

6. The number of vacuum holes is too small or the hole diameter is too small, and the vacuum degree is low. Vacuum holes should be appropriately added or the diameter of the vacuum holes should be increased. If possible, narrow vacuum slits can be used to replace the vacuum holes.

7. The capacity of the vacuum tank or vacuum pump is too small and the vacuum traction force is not enough. The capacity of the vacuum tank or vacuum pump should be appropriately increased, the vacuum pipe valves should be enlarged, and sharp bends should be avoided at tees and elbows.

8. The pressure of air pressure molding is insufficient. If the mold structural conditions permit, an air pressure of 137-206Pa should be used, or a frame booster or plunger can be used to assist.

Burnt

1. The heating time of the sheet is too long and the surface of the sheet is too hot. The heating time should be shortened appropriately.

2. The heater power is too high, the heater temperature is too high, and the heating speed is too fast. The heater temperature should be appropriately lowered and the heating speed should be slowed down.

Whitish

1. The sheet is cold drawn under low temperature process conditions. The temperature of the sheet should be increased to speed up the covering and evacuation speed.

2. The sheets used are dry colored. The appropriate sheet should be replaced, or a heat gun should be used to blow hot air on the whitened area to reduce or eliminate the whiteness on the surface of the sheet.

Cold Spots

1. The temperature of the pressure-assist plunger is too low. The temperature of the pressure-assist plunger should be increased appropriately.

2. The mold is too low, and the sheet in contact with the cold mold or cold plunger cannot be pulled. The mold temperature should be increased appropriately.

3. The mold cooling system is improperly designed. Cooling pipes or cooling tanks should be added appropriately and the cooling water flow should be checked for blockage.

4. The temperature of the sheet is too high. The heating temperature should be appropriately lowered and heated slowly. Compressed air can be used to slightly cool the surface of the heated sheet before molding.

Uneven Thickness

The problem of uneven thickness mainly depends on the temperature control system of the pressure forming equipment, which is the main cause of uneven thickness. Secondly, the quality and thickness of the raw materials are uniform, which is closely related to the produced products. In addition, there are Whether the upper mold is made to standard, etc.

Scratch or Hairline Problem

The problem of scratches is related to many factors, ranging from the raw materials themselves, machine operations, machine passing, punching, folding, packaging, etc. This phenomenon may occur. This is mainly based on customer requirements. If Customers are very concerned about this issue, so we must pay special attention to preventive measures during the production process.

There are two main phenomena for wire hairline problems. One is that the material is overcooked, and the other is caused by poor upper molding. Both of these situations are to be avoided by the operator during the production process.

Burst Problem

The problem of bursting is mainly determined based on the properties of the material itself. Some materials are very brittle and are prone to bursting during the production process. In addition, when producing APET materials, the material does not have enough silicone oil, and bursting may occur. There are also It has something to do with the weather. In winter, materials are relatively brittle, so special attention must be paid to the raw material formulation.

Water Ripples

In the production process of thermoformed sheets, due to different materials and processing techniques, the surface of the produced sheets has water ripples. Especially in the production process of transparent thermoformed sheets, the water ripples are too large and often , regarded as defective products. In general, the thicker the sheet, the more obvious the water ripples will be. Qualified PET materials rarely have water ripples, but most PVC have water ripples.

Mold Damage

During the vacuum thermoforming process, the mold may be damaged due to excessive temperature or excessive pressure. The temperature during the thermoforming process can be controlled to avoid mold deformation or damage caused by excessive temperatures. Adjust the pressure during thermoforming to avoid mold rupture due to excessive pressure.

Color Difference Problem

During the vacuum vacuum forming glue process, color difference problems may occur, which may be due to uneven color of the material or improper temperature during the thermoforming process.

Avoid using materials with inconsistent colors by using materials that are uniformly colored. Or control the temperature during the thermoforming process to ensure that the material is heated evenly and avoid color difference caused by too high or too low temperature.

Conclusion

Solutions to common problems in vacuum forming mainly include solving problems such as bubbles, rough surface, inaccurate dimensions, product deformation, color difference, surface defects, mold sticking, easy breakage, odor and low production efficiency. By optimizing raw material selection, mold design, heating temperature and cooling process, these problems can be effectively solved and the quality and production efficiency of vacuum forming products can be improved. In actual production, adjustments and improvements should be made according to specific conditions, and technical levels and processes should be continuously improved to meet market demand.

Thermoforming involves heating, vacuum forming, cooling and other processes of PVC, PS, PET and other resin sheets in a thermoforming machine to shape them according to the shape of the mold, and then punch them into a single product using a die on a punch machine, and finally packaging products made through folding, punching and other processes.

This kind of packaging product has the characteristics of cheap materials, simple technology, low investment and considerable profits. It is suitable for packaging small daily necessities, small electrical appliances, toys and other commodities. It is not suitable for packaging products with high cushioning requirements and heavy products.

Compared with traditional cold forming processing technology, hot forming process is characterized by a constantly changing temperature field on the processed sheet. Under the action of the temperature field, the basic structure and mechanical properties inside the sheet change, resulting in changes in the stress field of the sheet. At the same time, the stress field of the material reacts on the temperature field. Therefore, the vacuum forming plastic manufacturing process means that the internal temperature field and stress field of the sheet coexist and Mutually coupled change processes.

There are several thermoforming methods used in actual production, and the most basic ones are six: differential pressure forming, overmolding, plunger-assisted molding, suction molding, countermolding, and twin sheet forming.

Ⅰ. Thermoforming Production Process

The main production processes of thermoformed products include mold removal, pull tabs, punching, folding, punching, packaging, etc.

Mould or Drawing

A thermoforming project starts with design, which requires a model or drawing of the product, or a sample provided by the customer.

Mold Design & Making

After the customer confirms the sample, the plaster mold used for proofing is used as the master mold. After electroplating copper, the production mold is made according to a certain quantity and position. There are three types of conventional molds: plaster mold, copper mold, and aluminum mold. The plaster molds are mainly used for proofing and generally cannot be used for mass production. The production time is generally 24 hours.

The copper mold is a plaster mold electroplated with a layer of copper, which has enhanced strength and wear resistance and is not high in cost. It is the most commonly used mold in production. The general production cycle is 100 hours, at least 3 days, and the service life is about 100,000 pieces. When the quantity reaches more than 1 million, aluminum molds can be made.

The aluminum molds are made of pure aluminum, which is costly and requires machine processing. The general mold making time is 3 days. Aluminum molds have good production quality, fast heat dissipation, high product precision, and long service life. If the customer requires precise products and the copper mold cannot meet the accuracy requirements, aluminum molds must be made even if the quantity is small.

Install the Mold

Based on product and material information, the mold's cavity count and expected cycle time can be estimated. With this data, the moldmaker has all the details to build the tooling accordingly. The mold consists of two mold halves, each mounted on a removable platen of a vertical toggle press.

Heating & Forming

The thermoforming machine heats the raw material coils or plastic sheets through the vacuum forming machine, vacuum thermoforms them, and cools them, and then automatically cuts them into predetermined sizes. This process is the most important process of pressure forming.

The length of the sheet is between 600 and 1170mm according to actual needs. Different materials, different thicknesses, and different temperature adjustment requirements require considerable experience from the startup personnel. The adjustment test usually takes 3 pictures.

Punching

After heated plastic sheet and forming, there are usually multiple products (according to the number of mold rows), which need to be punched into a single product on a punch. This process is called punching.

If the customer has special requirements, this process should be added when perforating the thermoformed part.

Folding

For some products that need to fold over two or more corners of the thermoformed product to insert paper cards, this process is required. This process is completed by a folding machine.

Package

Must pay attention to the packaging of thermoformed products, and determine the appropriate packaging method according to the strictness of customer requirements, product materials, shapes, etc.

If the customer has no special requirements, packing and plastic bags can be used. For products that are white or brightly colored, easily scratched by friction, or cannot attract dust or fingerprints, gloves are often worn during production.

Ⅱ. Thermoforming Materials

Commonly used vacuum forming materials include PVC (accounting for approximately 50%, density is 1.36g/cm³), PS (accounting for approximately 30%, density is 1.06g/cm³), PET (accounting for approximately 10%, density is 1.39g/cm³) , PP (about 10%, density is 0.92g/cm³).

Among them, the maximum thickness of PVC is generally 0.8mm, and that of PS is generally up to 1.2mm. Films exceeding this thickness are difficult to pull and may easily cause damage to the equipment.

The color of the material is generally determined according to the customer's requirements. Generally, PANTON color standards, color drafts, color separation standards, etc. need to be provided. The customer can also specify the approximate color and provide the customer with the color based on the product inventory. If there is no requirement from the customer, generally colorless and transparent materials that are easiest to produce can be used.

If you order colored sheets, they generally need to be more than 2 tons before they can be customized. Colored materials are denser than transparent materials. Flocking materials generally use PS materials with smaller density. If the density is high, it is easy to produce lint-free parts of the surface after stretching.

Generally, materials with brighter colors are easier to produce and do not have high requirements for packaging. Scratches on light-colored materials are easy to see, so packaging requirements are strict. Generally, flocking materials need to be protected from scratches and indentations.

When the products are put together, friction will easily occur in the tight contact areas and cause them to turn white. In places like this, special attention must be paid when packaging. If the requirements are strict, consider using plastic bags, copy paper and other methods for protection. Flocking materials are generally ordered according to length (meters).

Material properties generally include anti-static properties. Anti-static materials are produced by soaking or adding anti-static ingredients. The latter method has long-lasting anti-static properties. The static value of anti-static materials can generally reach 106~1012Ω.

In addition, there is environmental protection, among which APET is the most environmentally friendly and PVC is recyclable. Generally speaking, the thicker the material, the longer it takes to heat and the slower the production speed. The thinner the material, the faster it can be produced, but the longer the roll will be.

Ⅲ. Thermoforming Mold

Lower Mold

The lower mold is an essential mold in thermoforming production. According to different production processes and materials, they can be divided into plaster molds, copper molds, and aluminum molds. When customers provide samples, drawings or physical objects, plaster molds for adding samples need to be made.

The gypsum mold is made of gypsum powder and water is added to it to set it into a certain shape. It hardens after dehydration to form a mold. Materials and tools such as gypsum powder, drill bits, emery cloth, and wooden boards are required. Because it is handmade, there will be a deviation of about 2mm from the drawing. Plaster molds can be prototyped directly after being made and are not suitable for mass production.

The plaster mold can be modified after it is formed, and it is generally easier to make it smaller than to make it bigger. After the customer confirms the sample, the proofed plaster mold can be used as the seed mold (master mold), and multiple sub-molds can be produced according to production needs. The size of the sub-mold will not deviate greatly from the seed mold, generally around 0.5mm.

After the lower mold is made, it needs to be fixed on a plywood about 8mm thick, and then it can be mounted on the mold basin during production. When the heated sheet passes through the mold, it is sucked by the vacuum pump and attached to the lower mold to make a product with the same shape as the lower mold.

Upper Mold

Sometimes vacuum suction alone is not enough to shape the product, and a certain external force needs to be applied to make the upper mold. The upper mold is not required for all products, but depends on the needs of production.

When testing the machine, if the thermoforming is not good and a upper mold is needed, the operator will make the upper mold according to the shape. The material of the upper mold is generally iron or wood, and the surface in contact with the product needs to be wrapped with soft sponge or flannel.

Cutting Die

Generally, multiple vacuum forming molds are used to open multiple molds. After forming, they need to be cut into finished products according to the size and shape of the product. The process of cutting into finished products is the punch press, and the mold used is the cutting die.

Cutting die can be divided into three types according to different materials and production processes: iron dies, wood die, and laser cutting die. Among them, iron die are thicker and can generally be made into cutting dies with more regular shapes, such as rectangles, ovals, etc., and are not suitable for shapes that are too curved.

The blade used in the wooden die is the beer machine cutting die used for color boxes. It needs to be stacked with a certain number of layers according to the height of the product, and sometimes a cushion is required. For cutting dies that require higher precision, laser die can be made, similar to wood sample knives.

After the die is made, the product that needs to be positioned generally needs to be fixed with a finished product in the die to facilitate positioning when punching the product. For products that do not require positioning, such as edgeless thermoformed products, iron knives are generally used as molds.

Ⅳ. Dimensions and Tolerances

Thermoforming dimensions can be obtained in three ways: copying according to customer samples, making molds based on drawings, and designing by yourself based on the actual object. Because the shape of pressure forming is generally customized based on the actual object, the shape is often irregular. Many dimensions are inaccurate or cannot be marked when the drawings are made, so there is a large deviation when making according to the drawings. For the sake of accuracy, it must be accompanied by a physical trial installation. The size deviation of products made based on sample replicas is not large.

The general thickness tolerance is 0.1mm, and the product deviation is ±2mm. The main reasons for tolerance are:

1. Deviation caused by manual mold removal. This deviation is generally less than 2mm.

2. Deviation caused when the seed mold copies the sub-mold. This deviation is small, generally less than 0.5mm.

3. Thickness deviations in the same mold caused by different materials and thermoforming temperatures. This deviation is small, generally less than 0.1mm.

4. The thickness tolerance depends on the specific situation. The larger the same area is stretched, the thinner the thickness of the piece becomes. Different operators and different forming temperature will also make the thickness of the same part different.

Among the above reasons, the first one is the main reason for dimensional tolerance, but because the mold can be modified and corrected, the deviation of thermoforming process can generally be controlled within 2mm.

It should be noted that the material thickness is two sizes (0.05mm) smaller than the finished product thickness. Although there are phenomena such as when the surface area of the finished product is much larger than the surface area of the material, the thickness of the finished product will be much smaller than the thickness of the material, the surface area of the finished product is much larger than the surface area of the material, and the thickness of the finished product will be much smaller than the thickness of the material, but overall Generally speaking, the general difference is 0.05mm.

Vacuum forming is a very definite product. If you want the size to be right, you must take the actual product and try it out.

Ⅴ. Draft Angle

All products stamped with molds need to set the draft angle during design, and the same is true for thermoforming. The general draft angle for thermoforming is 3°. The draft angle will cause the size of the upper surface to be smaller than the size of the lower surface. If the thermoforming is placed in a box, there will be a gap between the upper surface and the box wall. When the draft angle is the same, the size of the gap is related to the height.

Calculation Formula

The calculation formula is: d=h×tgθ

d——Size of the gap on each side.

h——Height of thermoforming.

θ——Draft angle, usually 3°.

Ⅵ. Mold Layout and Material Setting

Mold arrangement refers to arranging the molds on the mold plate and fixing them. The distance between the molds depends on the height of the product. The general rule is that the distance between the molds is equal to the height of the mold, and the distance between the mold and the four sides of the mold plate is equal to the height of the mold divided by 2. The high point of the mold refers to the highest point of the mold.

The height of the product refers to the highest dimension of the product. See Figure 2-1. Neither h1 nor h2 is the height of the product. The largest h is the height of the product.

When arranging the mold, the width must be arranged to the edge. The length can be more or less, but no more than 1120mm at most and no less than 600mm at least. Between 600 and 1120mm, the longer the better. The number of molds for APET materials cannot be too many, between 600 and 800.

The mold plate width plus 50mm equals the material width, and the mold row length plus 50mm equals the sheet length.

Conclusion

Thermoforming is a process that uses high temperature and high forming pressure to form raw materials into products of the desired shape and structure through steps such as heating, air pressure regulation, and cooling. This process can be used for processing materials such as plastics, metals and ceramics. By controlling parameters, products with different properties, shapes and sizes can be manufactured. The hot press molding process is widely used in automobiles, electronics, aerospace and other fields, providing high-quality products to all walks of life.

Thermoforming technology is plastic sheet (plate) thermoforming processing technology. It is one of the plastic secondary processing industrial technologies. The main principle is to heated sheet to soften it and then use vacuum to adsorb it to the surface of the mold formed after cooling, widely used in plastic packaging, lighting, advertising, decoration and other industries. Thermoforming can be divided into male mold and female mold according to the different contact surfaces between the molding material and the mold.

Ⅰ. Positive Mold and Negative Mold

Positive mold thermoforming and negative mold thermoforming are both plastic processing methods, which are a method of using thermoplastic plastics to form products through a vacuum forming process. The characteristic of female mold thermoforming is that the bottom of the mold is concave, and the workpiece is heated and softened above the mold and then adsorbed to the bottom of the mold to form the product. In the male mold thermoforming, the bottom of the mold protrudes, and the workpiece is heated and softened below the mold and then adsorbed above the mold to form the product.

Negative mold thermoforming is to place a hot soft plastic sheet in the mold, then apply negative pressure (pull it outward) to make it close to the surface of the mold, and heat and soften it before forming. Positive mold thermoforming places a hot soft plastic sheets outside the mold, and then applies positive pressure (that is, inward pressure) to allow it to swell into the mold and form.

Positive and negative forming for vacuum forming, only one side of the heated material is in contact with the forming tool. In this way, the surface where the material meets the mold has exactly the same sheet surface profile as the forming mold. The contour and size of the non-contact surface of the molded part only depends on the thickness of the material.

Ⅱ. Thermoforming Process

Positice Mold Thermoforming Process

The positivee mold thermoforming process is more advantageous for manufacturing products with larger wall thickness and depth. The main features of the product are: like the vacuum female molding method, the side of the mold cavity wall that fits is of higher quality and has a more distinct and detailed structure. The largest part of the wall thickness is at the top of the positive mold, while the thinnest part is at the junction between the side and the bottom of the positive model. This part is also the last part to be formed.

Drawing and cooling stripes often appear on the side of the product. The reason for the stripes is the sheet material. There is a sequence when each part fits the mold surface. The part that is in contact with the mold surface first is cooled by the mold first, and in the subsequent related processes, its drafting behavior is weaker than that of the uncooled part. This streak is usually highest on the sides near the top of the mold face.

Negative Mold Thermoforming Process

The side of the product produced by the vacuum negative molding method that fits the mold cavity wall is of higher quality, and the structure is more distinct and detailed. The largest part of the wall thickness is at the bottom of the mold cavity, and the thinnest part is at the junction of the side and bottom of the mold cavity, and As the depth of the mold cavity increases, the wall at the bottom corner of the product becomes thinner. Therefore, the vacuum negative molding method is not suitable for producing products with a large depth.

For positive molding, the inner dimensions of the part are very accurate because it is the side that interfaces with the vacuum thermoforming tool. In contrast, with negative molding, the outer dimensions of the product are very precise because the outside is in contact with the vacuum thermoforming mold.

Ⅲ. Advantages and Disadvantages of Positive and Negative Mold

Positive Mold Thermoforming

Advantages:

1. The product has a smooth surface and good quality.

2. The mold investment cost is low and the service life is long.

3. The molding cycle is short and the adaptability is strong.

Disadvantages:

1. The molding accuracy is low and is only suitable for manufacturing simple geometric shapes.

2. Unable to manufacture larger size workpieces.

3. The surface quality is relatively poor. Since the pattern is premade, the pattern effect will be lost during the stretching process of the skin. Where the amount of stretching is large, the pattern will become very shallow or even disappear.

4. There are restrictions on the R angle of the parts.

Negative Mold Thermoforming

Advantages:

1. The molding precision is high and more detailed and complex workpieces can be manufactured.

2. Larger size workpieces can be manufactured.

3. Mold production and use costs are low.

4. The surface is smooth and the surface pattern effect is relatively good

5. High production efficiency and reduced reprocessing costs.

Disadvantages:

1. The plastic material utilization rate is low.

2. There may be problems with the surface quality of the product.

3. Mold investment costs and equipment requirements are high.

4. The molding cycle is long and the molding cost is high.

Ⅳ. Attention Should be Paid to the Production Process

Positive Mold Thermoforming

1. When using high angle molds for processing, especially when the distance between the mold and the clamping frame is large, wrinkles are likely to occur.

2. Cooling strips are easily produced at corners.

3. Uneven wall thickness at the flange.

4. It is difficult to demould due to insufficient slope of the side wall.

5. A small gap will occur between the insert and the lower holder of the multi-cavity mold in the molding area (clamping mold frame).

6. Positive mold forming molds are usually cheaper than female molds.

Negative Mold Thermforoming

1. Thick edges.

2. Uniform edge thickness.

3. Thin corners.

4. The single female mold has good demoulding properties.

5. Female molds are usually more expensive than male molds.

Ⅴ. Application

Thermoforming negative and positive molds are widely used in color TVs, automobiles, electrical appliances, communications, aerospace, medical equipment, toys, sporting goods and other fields. Common thermoformed products include automobile body parts, remote control casings, medical braces, aircraft models, etc.

Negative molds vacuum forming is usually used to produce products with convex and concave surfaces, complex shapes, and precise dimensions, such as automotive interior parts, medical equipment, electronic product casings, etc., and is suitable for mass production.

Positive mold thermoforming is suitable for producing flat and simple curved products, such as daily necessities, toys, display items, etc., and is suitable for small batch production.

Ⅵ. How to Choose Positive or Negative Mold

The choice of negative mold thermoforming or positive mold thermoforming depends on production needs. If complex workpieces or larger-sized workpieces need to be manufactured, negative mold thermoforming is more suitable. If you need to produce simple geometric shapes or products that require high surface quality, or require high production efficiency, then positive mold thermoforming is more suitable.

Generally speaking, both negative mold thermoforming and positive mold thermoforming have their own advantages and disadvantages. Choosing different processing methods under different circumstances can better meet production needs.

Ⅶ. Thermoforming Mold Materials

Plaster Molds and Glue Molds

The plaster mold is mainly made of yellow thermoformed hand plaster gypsum powder. If there is a drawing, the gypsum material will be made into a mold according to the data on the drawing and relevant requirements, if there is a physical object, the outline of the mold must be completed according to the actual object. First use handmade clay to make it, and then use vacuum forming to make a vacuum cover. Then there is a plaster mold, and then it is slightly trimmed.

This process only takes 2-4 days to complete, the comparison of making plaster molds It is easy, takes less time, is convenient to modify the product packaging, and its price is not high, but it does not take long to use, and after a period of time, it is easy to damage, and its transparency is not good, so it is mainly Used for products with low transparency requirements or first board confirmation.

The rubber mold is generally based on the design requirements of the product. After the plaster mold is made, a vacuum cover is produced from the plaster mold, and then high-temperature resistant resin material is injected into the vacuum cover.

After the mold is dry, holes can be drilled and polished. It takes a total of 3-5 days to complete, the price of resin molds is higher than other molds, but its use effect is similar to that of copper molds. It takes a long time to use, and some copper molds and plaster molds cannot be processed. Technical problems can be solved, so it is mainly used in electronics, food, toys and other products.

Knife Mold and Punching Mold

Mainly used in punching and drilling (airplane holes, round holes and butterfly holes).

Electroplated Copper Mold

The appearance and transparency of products produced with electroplated copper molds are relatively good, and their prices are not high and they are widely used. This is the first choice mold in general. It is used in products with higher requirements, such as electronics, stationery, toys, etc.

Bakelite Mold

The production of various bakelite molds is completed with imported heating materials, high-quality copper nails and Japanese high-temperature tape. Its characteristics include uniform heating and good sealing effect. It can be used in various disc machines and fully automatic chains. Machines and tractors made in Taiwan, it is mainly used in heat-sealing packaging of paper cards and bubble shells.

Aluminum Alloy Mold

According to the drawings or templates you have, input the data into the computer and let the computer lathe complete it automatically. Then you will complete the other holes manually and polish the mold smooth. The mold is ready for use. It will take 5-7 days. time. It is widely used in products with high requirements on appearance and size, such as electronics, toys, medicine, etc.

In fact, alloy aluminum mold is the first choice mold for the production of many high-demand air pressure forming products. For plaster molds and copper molds, glue The mold lasts longer, the production efficiency is not low, and it can save time and electricity, which are its advantages.

Heat Sealing Mold

Use high-quality copper or alloy aluminum to make heat-sealing molds, which mainly solve the problem of difficult sealing of PET with high-frequency heat. Its surface is treated with Teflon, which is also suitable for PET molding, the pattern on the pressed edge can be engraved by computer, with clear lines and uniform size, and various patterns can be customized according to user needs .

High Frequency Mold

The materials of the high-frequency mold have high-quality crimping lines, cutters, and very smooth cutting edges without any burrs or tearing edges. The pattern of the pressed edge is also engraved by computer. Its texture is also very clear and the size is uniform. It is also customized according to the user.

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