#bending tooling

For the Promecam tooling system, we offer 4V and 3U bending dies. These dies are the most universal product for starter sets for press brakes and have the economic possibility of working with different thicknesses. These dies could just be turned around to get other V-openings. It is also very effective for the customer who just starts to work with the press brake and has the necessity to prepare their actual parameters for die opening and tonnage to be used.

We also have a polyurethane insert for the V50 opening, so you can work to bend in polyurethane as well. And together with our 3U die, you can have the complete range of main used openings from 6 mm.

More information in our blog article about 4V / Multi-V bending dies for press brakes

We came today with a new, interesting text topic.

Bending of radius shapes is a tricky thing. If it is a U-shape (or U-channel) (this means the sides should be 180 degrees) it will be a double tricky thing and it is impossible to achieve with the standard tools. The solution for bending should be to close the part more than 180 degrees to have the coefficient of return when the part is extracted. We are talking about it also in our blog. The hard story is that the radius bend makes the big spring back and it is not just a couple of angles. We study different ways of bending from offering standard tools to bumping tools with completely special complicated solutions.

Normally it is reasonable to say that this subject is outside our range of job. We are writing about press brake tools because we supply them but automation of bending is the subject dedicated to the manufacturers of press brakes. Yes, mostly true and here is why we made idea for this article. There was the request where the customer want to bend steel with 25 mm thickness. Nothing special and it is possible to offer the quotation but also is necessary to justify could the machine will be able to provide the high tonnage at one area without any damage and deflection. And moreover it was standard Promecam system which is normally only for 100 t/m and the reason to change intermediates for thicker one. All of these things are not standard but not really complicated to deal with and moreover we checked the possibility to supply adapters to move to Trumpf-Wila because for this system and width 20 mm tools 200 t/m could be possible. Ok, but what is here about automation? Will explain. Customer wants to buy press brake tools to start new production. But what is the weight of part? Mainly it was quite small width but more than 35 kg. So how you will deal with it? It is possible to make the project and to calculate everything but how to handle the part of big weight if it will be real typical production with quantities each day? And funny story that customer didn't think about it too. And this means that all our stuff could be completely useless if the customer can't handle the part in production. No, he can organize the handling with two workers or workshop light crane but the constant manual handling doesn't lead to the normal production. So the first reason is not to think about the tools but to know about automation. For several bends and new press brake it could be the following frontal support which follow the part during the bending. But to make the full handling it is necessary to think about automatic or semiautomatic system to move the part or robotic solution. Yes, the first field of automation is not the repeatable massive job but the heavy parts where manual handling is quite hard or impossible. Moreover the market offers also the solutions for existing press brakes to equip them with automatic system. The other story is massive production. Work of press brake operator is not the easy one. He need  all the hours to stay at the front of the machine and to make the moving of pieces one by one. If the job really repeatable, robot could be really great solutions to increase the productivity and moreover to enter the mode of 24 hours working shift. Moreover there are different developments to change the jobs, change the press brake tools, change the pallet for loading and unloading of parts etc. It is useful to know that the robot is also very flexible investment if you made the right choice - tomorrow you can move it to other applications and install welding system for example. Robotic sheet metal bending not so massive product like welding cells for example but there are a lot of reasons to run with robots. And it is also the side of the investment to new digital technologies, modern factory and the latest innovations at the field. It is interesting also to see that some manufacturers develops also robotic innovations to change the press brake tools with second robot on fly. With one robot it is quite problematic because the necessary to change the gripper. But if you are looking for really fast production and change of working cycles there are possible to supply also special tool racks together with robot or other manipulator to prepare on the press brake new tools for the new job. It is interesting to know that automatic solution could be also not the stand-alone bending cell but the connection to other systems, for example transfer the parts from punching or to and from other areas. There are a lot of fantasies and projects which should be true - several robots for long parts, gantry systems or rails for robots to move it out of press brake area if necessary to work by operator again, small work of punching station, fastening operations etc. In addition automatic cell is the part for digital factory or Industry 4.0 which is today the first name to develop the modern workshop.

Ok, a lot of articles how to choose and what to keep in mind to purchase press brake tools. Now this is the time to tell how it could be easily broke or defected.

First thing to know from the customer side - normally press brake tools are investments for years. Nobody can tell you the real duration of life to use but it really could be years depends of all circumstances you have during the bending process. Normally it is also possible to provide the guarantee, why not, but it is just not typical in tooling practice because everybody knows that tooling is the subject of wear and tear. Anyway it could be really long period of use, thousand of bends and even normal condition after it if the caring about the recommended conditions will be performed.

Why important to follow all recommendations? It is very easy - damage of the tool is the reason to replace the tool completely and to purchase the new one. But even small damages and scratches are the problem because they will effect result of bending in terms of precision and quality of surface. Even small defect will be the reason to see the problem on the final part. It means - for example, operator didn't realize the small damage of tools and continued to work several days and, finally, as the result production has hundred of defected parts. The second importance. The purchased tools, for example, were made with special geometry and the cost was twice or triple than standard. The defect for this type of tool means more expensive for production to replace.

Now, from small to big...

To care about the adherence if to work with aluminum or zinc plated sheets. This will effect for the fast and accelerated die wear and the real remedy is only to order the tools with special coating. The temporary solution - to have near the air blast or air gun to clean the tools during and after the work. 

Burrs, even small mean that first you bend the burr and after - the bend you need. Burrs are the good subject for high wear of tools and the main solution - manual or automated deburring of sheet metal parts before bending. Lot of companies do not think that small burrs are really important but even small burrs are the problem for high volume production.

Storage as the last and simple. Keep your press brake tools clean and properly stored. Yes, you can store them as the pile, do not care about the conditions and corrosions to finally have marked and scratched scrap of metal to bend just something not precision and simple. If the customer cares about his production he should to be care about his tools as well. Unfortunately we met a lot of situations when the tools are stored as the pieces of metal.

Customer bends other things... This is really story from life when the customer several weeks after receipt of new tools started to bend bars. To bend something outside of flat sheet metal parts is the subject for additional study and for sure nobody will give you any guarantee for the process and efficiency of tooling. Moreover the customer bended bars with coining process and after several bends he damaged the bottom of die opening. You should know - the bottom of die opening is outside of working zone for standard air bending process so this area is not hardened also. Moreover during bar bending the force is provided from the top of bar and not distributed like sheet metal bending. Anyway, if such special applications are presented the main reasonable way - to ask the tool supplier and the supplier of press brake about possibilities to make without any risks. Otherwise there are different possibilities to damage. And we should say that in our example the customer was lucky just to damage the cheap die.

Tonnage and limitations. Usually sheet metal bending is connected with small thickness parts. For these applications 100 ton, 3 meter machines, so 33 tons per meter and no any problem with the tooling or the machine. And everything changes when the customer wants to make thick material, use the force of press brake in one area without length distribution, work with hard resistance materials or ignores the way of air bending and tries to make small radius started with coining.

The results could be dramatically - damaged dies, bended punches with the deflection of the center line, problems with the machine. Any big force activity is subject for study - reason to change the tooling from standard ones to special with more high limits, subject to speak with the manufacturer of the machine and to think double time about all possible problems. There are lot of possibilities to reduce the tonnage like increase of V-die opening so the customer should follow the limits and moreover do not make overloading more than 80% to leave 20% for all possible risks.

It is also very important to know. For all main tool manufacturers even high forces bending is the main theory so it is possible to review the possible tonnage to guarantee based on the thinnest area of tool and used tool material. For example for Promecam 100 t/m is the limit because tang width 13 mm only. Ok, it is possible to install heavy duty intermediates. But... there are also bolted clamps, will they be ok for 200 t/m force? Hard to say. So this is the reason to be very accurate with high tonnage applications. And if possible to leave them for big tonnage press brakes and heavy duty tooling from the begin.

Press brake bending is the theory for all press brake tools manufacturers. When the customer asks for tonnage, springback, tolerance, angle - all what is possible to provide is the main theory. Yes, it is based on some experience, formulas, ideas and calculations but when the tool was not tested with your steel - there are only theoretical parameters. Moreover everybody who works in production is informed that even the same trademark of material from different batches could lead to different results in deformation. How theory becomes practice. There is no magic - nobody of press brake tools manufacturers has in workshop press brake even for 100 tons to test all parts. So normally any test goes to the small length of part to test with compact press brake. Moreover if customer asks strict tolerances probably everybody ask for bigger gap - it is hard to take all costs for mistakes and to guarantee something extremely precise and special. And there is other black spot - even if you can test tool for 100 mm it doesn't guarantee that results will be the same in two meters - there are longitudinal relations as well. But anyway if the tooling should be shipped and the shape is special, it is impossible to ship the theoretical shape and non-tested production result because the manufacturer should have some obligations about the tool he developed. That is why the question in-shop testing is necessary and should be solved before shipment. How to test if possible to test? There are two main available small costs practices: laser cutting sections with welding or plastic based dimensional printing. Plastic based printing is completely new solution with incredible advantage - just necessary to have 3d printer to make the prototype. But there is also one big disadvantage - plastic is not the metal and this means strength of plastic is enough to test special tools for thin material applications. But anyway plastic prototypes have the good future for development - 3d metal printing is the nearly future. Moreover to add more strength to the tool it is made not only with plastic 3d printing but with some internal metal inserts around the working zone to prevent some big deformation. Anyway it is not the working solution but the tool for tests. Laser cutting together with the welding - traditional testing process to make small section of special tool. Disadvantage of the process is the access to laser cutting machine but the advantage that you will have real metal not hardened tool with the necessary shape to make the test bend. Is there the future for development? Hard to say but replacing of laser cutting to waterjet can give the possibility to cut solid sections about 50 mm or more with greatest precision. It is also important that the costs for preparation of such shape are very low to make just several cuts in one sheet. What is the final for the test? Normally the bend quality and geometry which is acceptable by the customer to start the manufacture of normal bending tool with proper material and hardening. Or the feedback that allows to make modification. The reason of testing and testing tool prototypes is very important - nobody wants to deal with the modification of prepared and hardened tooling after the sale. And any possibilities should be used to reduce to the minimum of any risks. So the test prototype is the way to control the deformation to remake the theory into the real bend. Anyway every repeatable process has the solution to realize but based on the limits for part and the tool. It is the question of experience and the field knowledge. The main point is usually only one - customer has the real and reasonable requirements and accept the calculations of special tools. All other should be the subject of study. And there is no the black point, even with thick material is possible to make the modulation of forces and stress to have the theory realistic. It is not usual procedure but helps to terminate the black spots.