Our product range comprises racks with straight and helical teeth in ground as well as milled design. We manufacture standard solutions as well as special solutions in various modules, dimensions and materials, as well as hardened and coated.
Selecting The Right Rack & Pinion Drive
When selecting a rack and pinion drive, it is important to gather as much information as possible about the specific application so the maximum forces, speed, accuracy and lifetime can be determined.
Forces:
The typical forces on a rack and pinion drive are from:
- Acceleration and deceleration forces to move a mass (F = ma)
- Friction from the type of linear supports used (linear rails, rollers, ways, etc.)
- Additional process forces such as cutting, welding and clamping forces.
The full duty cycle should be evaluated to determine when the peak cycle forces occur. In most applications, the peak cycle forces happen during acceleration so the sum of the above forces is typically used.
Accuracy:
The accuracy of a rack and pinion drive is usually defined by the required positioning accuracy and repeatability. Positioning accuracy is dictated by the cumulative pitch deviation of the gear rack, which is the linear error from tooth to tooth and is a function of the manufacturing processes used (see above).
For example, a gear rack with a pitch deviation of +/- 0.200 mm over 1,000 mm would mean the actual rack length would deviate between 999.8 and 1000.2 mm compared to the theoretical length of 1,000 mm.
This linear error can be minimized by using high quality gearing or by mapping the errors to minimize the cumulative error. In some cases, it is possible to compensate for the error and completely eliminate it for full length of the axis.