Dinesh Mallipeddi
​Dinesh Mallipeddi defending his doctoral thesis.
Phot​o: Nina Silow

Zooming in on gear teeth

​Congratulations to our new doctor Dinesh Mallipeddi who today successfully held his doctoral defence with the title: Surface Integrity of Gear Materials.
Gears are an integral part of modern life, necessary for both production and transport. The compact and efficient transmission offered by gears made their usage predominant compared to other drives. Recent development have increased both the efficiency and durability of gears, especially in the automotive industry. Still, enhanced performance is required due to global demands on sustainability and energy consumption. Actually, one billion cars are rolling on the streets around the globe, without counting trucks and busses. This means even small increase in efficiency could significantly reduce the energy usage.​

A gearbox with gears of different sizes is part of a vehicle transmission system and plays an important part in transmitting the engine power to the wheels. The efficient energy transmission highly relies on the performance of gears. Together, the mesh efficiency and durability determines the performance of gears.

The hard finishing of gear surfaces can be done by different methods; grinding, honing and superfinishing etc., and produces unique characteristics in terms of surface roughness, microstructure and residual stresses. These characteristics of the teeth affect the gear performance. A running-in process is known to alter them along with the surface chemistry and it pre-sets the gear for service. By understanding the initial running-in it is possible to improve the performance of gears. 

– My study addressed the influence of running-in on the evolution of surface characteristics generated by the mentioned methods, and how they developed further during initial usage, represented by efficiency test. The surface roughness was found to be the most influential factor among all the characteristics. The findings that I have presented are expected to contribute to the technical and industrial aims for optimized gear preparation.

The research was conducted together with AB Volvo under the supervision of Senior Lecturer​ Mats Norell and Professor Lars Nyborg at Chalmers department of Industrial and Materials Science.

Published: Thu 04 Oct 2018.