Polisch Grinding: definitive guide to improve strength and durability of gears

maggio 03, 2023

Today we talk about Polisch Grinding, a surface finishing technology used to reduce the friction of gears and increase the contact ratio of the gear surfaces. The process is performed as a final machining sequence on continuously generating grinding machines, without interrupting the gear grinding cycle. That is, what is removed are the asperity peaks, which leads to lowering the height of the asperity profile by increasing the contact area of the gear surfaces. The polish grinding process can reach surfaces with a very low roughness, less than 1 µm in Rz and less than 0.2 µm in Ra.

Polish Grinding: Improved performance

Improved performance can come in a number of ways, including reducing noise and increasing gear strength.

The polish grinding process allows to increase the contact surface between the gears thanks to the elimination of surface roughness. This can reduce wear and friction between gears, which are the main causes of noise.

The contact surface between the gears increases and the load is distributed over a larger area, thereby reducing the specific pressure on the gear surface. As a result, there is a marked improvement in the fatigue resistance and fatigue fracture of the gears. In conclusion, therefore, polish grinding helps to make them durable and reliable.

Fields of application

The polish grinding process is mainly used for the production of high precision and quality gears. Especially for machine tools, aircraft, automobiles, wind turbines and power generation plants.

This finishing process is especially important for gears that operate at both high loads and speeds. As mentioned above, polish grinding is useful in cases where the precision of the gear and the reduction of friction are essential to guarantee the efficiency and reliability of the system.

Technologies used and functioning

The polish grinding process is performed through the use of a continuous generation grinding machine. That is, a system designed to perform both roughing and finishing machining in a single machining cycle.

Continuous generation grinding machines, such as Reishauer and Kapp, use technology to produce high precision gears. They also use a worm-shaped tool during the polish grinding process, while at the end of the stroke the grinding tool is used to remove only the roughness peaks and improve the surface finish of the gear without affecting the geometry of the gear . The first part of the tool has a coarser and more rigid conventional grain which is used in the roughing phase, while the final part has a much finer and more flexible grain.

The prospects for the use of polish grinding

The polish grinding process has very promising prospects in the field of gear machining, as it is able to significantly improve performance and reduce the noise of the transmission system.

Gears subjected to polish grinding are able to withstand higher loads and transmit torque more efficiently than gears machined with other finishing methods.

Also, because the process can be easily integrated into current continuous generation gear grinding machines, the implementation does not require large investments in new equipment. This means that this can be adopted relatively cheaply and quickly by companies already using gear grinding machines.

What we can expect is an increased demand for gears machined with this technique in industries where the reliability and accuracy of the drive system are of paramount importance, such as the automotive, aerospace and robotics industries.

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Polisch Grinding: definitive guide to improve strength and durability of gears

Polish Grinding: Improved performance

Fields of application

Technologies used and functioning

The prospects for the use of polish grinding

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