Lapping and grinding are the two main processes for bevel gears. While both aim to get better gear tooth surfaces, they have difference in mechanisms, capabilities, and performance characteristics to the final product.
- The Lapping Process
Lapping involves running a gear set (bevel pinion and bevel gear) together in mesh under load with abrasive paste applied to the teeth. The primary goal is to improve the surface finish and contact pattern between the mating gears, to get quieter and more efficient operation.
The material removal during lapping is very limited, the final quality of a lapped gear is highly dependent on the accuracy of preceding processes like gear cutting and heat treatment, as lapping has a very limited capacity to correct distortions caused by hardening.
- The Grinding Process
Grinding uses an abrasive wheel to remove material from the tooth, which can removal more materials, make it can correction of heat-treat distortions and the achievement of very high levels of precision, superior surface finish, and tighter tolerances.
The precision of grinding ensure a high degree of geometric consistency from tooth to tooth and from batch to batch. However, this high accuracy can sometimes generate a “pure tone” noise during operation due to precise tooth meshing impacts, which some find more noticeable than the broader noise spectrum of lapped gears. Modern grinding processes, especially those using advanced machine tools and cycles, have become economically viable for mass production in industries like automotive and aerospace.
The choice between lapping and grinding depends on application requirements.
Lapped bevel gears are a more cost-effective solution, requiring less expensive equipment and shorter production times. They are well-suited for applications demanding moderate precision, smooth operation, and where cost is a primary concern.
Ground bevel gears, with higher price to produce, offer higher accuracy, superior load-bearing capacity, and greater durability. They are the preferred choice for high-performance applications such as aerospace and high-end automotive transmissions where precision, reliability, and performance are paramount.