#belttoothprofile

A timing belt high-speed linear module is a linear motion system that uses a toothed belt, driven by a motor pulley and an idler pulley, to move a carriage along a linear guide rail at high speed. The belt teeth mesh with matching pulley teeth, giving positive, low-slip motion transfer without the pitch accuracy limits of friction drives. Compared with ball screw modules, belt-driven linear actuators support longer strokes, higher speeds, and lighter payloads, though with somewhat lower positioning accuracy. Belt pitch, tension, tooth profile, and pulley diameter together determine speed capability, vibration behavior, and repeatability across the module's working stroke.

Why Timing Belt Specifications Shape Vibration in High-Speed Linear Modules

High-speed linear modules move payloads across long strokes at fast cycle rates. Engineers expect smooth motion and stable positioning at every speed. However, a timing belt linear module can develop unwanted vibration once speed climbs past a certain point. Specifically, this vibration starts at the belt itself. The belt teeth mesh with the pulley teeth many times each second, and each mesh event creates a tiny impact. As a result, small variations in that meshing action build into a repeating force. This force excites the belt span, the carriage, and the payload together. Therefore, the right timing belt specification controls vibration before it starts, rather than after installation. Vibration inside a linear motion system affects more than operator comfort. It changes positioning accuracy, tool life, and surface finish on finished parts. For this reason, engineers choose belt pitch, tooth profile, tension, and material as one connected set of decisions. Overall, each specification interacts with the others in a real way. In addition, pulley diameter and span length also shape the vibration response of a belt-driven linear actuator. This article walks through each factor from a function point of view and skips cost figures entirely.

Belt Tooth Profile and Meshing Impact in Timing Belt High Speed Linear Module

Vibration in a timing belt linear module often starts with tooth meshing. Each tooth strikes the pulley groove at the start of engagement. Then, that same tooth lifts away at the end of engagement. This impact happens at a rate tied directly to belt speed and tooth pitch. Consequently, a poor tooth profile increases both impact force and impact frequency. A curvilinear tooth profile, such as the AT or GT-style profile, meshes more smoothly than an older trapezoidal profile. In practice, the curved flank spreads contact load across a wider tooth surface. As a result, the tooth deforms less under load, and the belt tracks the pulley pitch more closely. BRECOflex notes that the AT tooth profile carries half the backlash of the older T pitch profile. In turn, pairing it with a zero-backlash pulley yields the best repeatability. Meanwhile, Goodyear engineers developed a double helix tooth pattern for automotive timing belts. In testing, they measured a 19 dB drop in meshing noise compared with a standard belt of the same pitch. That result shows how much tooth geometry alone can shift the vibration and noise floor of a belt drive.

Belt Pitch Selection for Speed and Precision

Belt pitch sets the spacing between teeth. In turn, this spacing controls how often a meshing event occurs at a given speed. A finer pitch produces more frequent, smaller impacts. A coarser pitch produces fewer, larger impacts. Therefore, pitch selection becomes a trade-off between meshing frequency and per-tooth load. For high-speed linear modules, engineers often prefer a finer pitch when the payload stays light. The smaller tooth size lowers per-impact energy, so the resulting vibration amplitude stays lower even though impacts happen more often. In contrast, heavier payloads need a coarser pitch to keep tooth stress within a safe range. In practice, matching pitch to speed and load matters greatly. This step prevents the belt from becoming the weakest link in the linear motion system.

Belt Tension and Resonance Control in Timing Belt High Speed Linear Module

Belt tension holds the timing belt against backlash and keeps tooth engagement consistent across the full stroke. However, tension also sets the belt's natural frequency, much like a guitar string. A belt under low tension sags between pulleys, and this sag lets the free span oscillate at low frequency. A belt under excessive tension pulls the natural frequency higher. However, it also raises bearing load and wears the tensile cord faster. The goal is to place the belt's natural frequency away from the excitation frequency. This excitation frequency comes from tooth meshing and motor commutation together. For this reason, engineers calculate the meshing frequency at maximum operating speed first. Then they select a tension level that shifts the span's resonance frequency clear of that value. SDP/SI's engineering handbook explains that installation tension directly affects meshing quality. Consequently, drives with clean, consistent tension mesh with noticeably less vibration than under-tensioned drives. Additionally, radial runout on the pulley adds a secondary tension ripple once per revolution. For this reason, pulley quality matters just as much as the tension setting itself.

Belt Material and Tensile Cord Construction in Timing Belt High Speed Linear Module

The tensile cord inside a timing belt carries the load and sets the belt's stiffness. Fiberglass cords offer high tensile modulus and low stretch, so they hold pitch accurately under load. Steel-reinforced cords push stiffness even higher for very high load applications, but they add mass to the moving belt span. This added mass can lower the span's natural frequency. In turn, resonance moves closer to the meshing excitation frequency at high speed. Carbon fiber tensile cords sit between these two options. They combine a high tensile modulus with lower mass than steel. As a result, they support high-speed motion without dragging the resonance frequency downward. Meanwhile, the belt body material, usually polyurethane or neoprene, affects damping. A more flexible body absorbs some tooth-impact energy internally. By contrast, a stiffer body transmits more of that energy into the pulleys and the carriage. As a result, material selection becomes a balance between stiffness for accuracy and damping for smooth motion.

Pulley Diameter and Wrap Angle Considerations

Pulley diameter changes how a tooth enters and exits mesh. A small pulley forces each tooth to engage at a sharper angle. Consequently, impact force rises even at moderate belt speed. Pfeifer Industries recommends choosing pulley diameters larger than the minimum available size. This choice smooths tooth entry and reduces vibration in sensitive equipment. A larger pulley also spreads belt tension across more teeth in contact at once. As a result, load per tooth drops and meshing becomes gentler. However, a larger pulley increases the belt's linear speed for a given motor RPM. This shift can push meshing frequency into an unwanted resonance band. Therefore, pulley diameter selection works alongside pitch and tension, not on its own. Wrap angle matters too. A full wrap keeps more teeth engaged and spreads load evenly, while a short wrap concentrates load on fewer teeth and raises local vibration.

Comparison Table: Timing Belt Specification Effects on Vibration

The table below summarizes how each specification function relates to vibration behavior in a high-speed linear module. Specification Primary Function Vibration Effect Best Fit Scenario Fine tooth pitch (e.g., 3 mm) Frequent, small load transfer Lower per-impact amplitude, higher frequency Light payload, high-speed pick and place Coarse tooth pitch (e.g., 8 mm) High load transfer per tooth Higher per-impact amplitude, lower frequency Heavy payload, moderate speed Curvilinear tooth profile Distributed tooth contact Reduced impact force and noise Precision positioning, semiconductor handling High installation tension Backlash control Raises span natural frequency, raises bearing load Long travel, high acceleration Fiberglass tensile cord Load carrying, low stretch Moderate mass, stable pitch under load General-purpose linear axes Carbon fiber tensile cord Load carrying, low mass Keeps resonance frequency high at speed Very high-speed, long unsupported spans Large pulley diameter Smooth tooth entry Fewer, gentler impacts Sensitive optical or metrology equipment Full pulley wrap angle Even load distribution Lower peak tooth stress High-cycle industrial automation

Real-World Reference and Quantified Outcomes

Published belt engineering data gives useful reference points for these decisions. Pfeifer Industries' troubleshooting guide cites Goodyear's double-helix tooth design as one clear example. That design cut meshing noise by 19 dB compared with a conventional trapezoidal profile at equal pitch and speed. BRECOflex's technical documentation states that the AT tooth profile reduces backlash by half relative to the older T profile. This narrower backlash directly limits the transmission error that feeds vibration at each tooth-mesh cycle. SDP/SI's Handbook of Timing Belts, Pulleys, Chains and Sprockets also confirms that dimensional accuracy of the pulley shapes final meshing quality, not the belt alone. Pulley runout injects a once-per-revolution tension ripple into the drive. Academic modeling work published in the Journal of Sound and Vibration adds further support here. That research shows resonance in a belt-pulley drive comes from the interaction between tensioner stiffness, span length, and meshing frequency, not from any single component alone. This finding supports a system-level approach. A timing belt linear module performs best when tooth profile, pitch, tension, tensile cord, and pulley diameter get selected together. Engineers should keep the target excitation frequency for the specific application always in view.

Practical Guidelines for Specification Selection

First, calculate the meshing frequency at the module's maximum design speed. Multiply belt speed by the number of teeth per unit length, and this establishes the excitation frequency to avoid. Next, select a tooth profile suited to the required positioning accuracy. A curvilinear profile fits precision applications, while a standard trapezoidal profile can serve simpler transfer tasks. Then, choose pitch based on payload mass, since a lighter payload allows a finer pitch and a smoother vibration profile. After that, set installation tension so the resulting span natural frequency sits clear of the meshing excitation frequency calculated earlier. Finally, confirm pulley diameter and wrap angle. Together they should support smooth tooth entry without pushing belt speed into an unwanted resonance range for that pitch.

Function-First Conclusion with Timing Belt High Speed Linear Module