The gear cutting processes are delicate and accurate. But, at the same time, these operations are really demanding for the tools that, as a consequence, need to be sharpened very often (increasing the costs and reducing the productivity). Although cemented carbide is used sometimes, most of these tools are made of high speed steel, that has much better toughness. Due to their higher performance, the use of PM-HSS has become very common nowadays and the application of PVD coatings is nearly mandatory for the manufacturing of big batches.
Cryogenic treatments are particularly effective in these tools since HSS respond well to these processes. Remember that the tools only have to be treated once because their whole volume is permanently affected by the treatment. Thus, those that are sharpened many times throughout their life will benefit from greater potential savings. Hobs, gear shaper cutters (shank, disc or rack type), broaches, inserts, etc. intended for machining gears and transmission elements are regularly treated at IK4-Azterlan facilities. The multistage cryogenic treatment is a simple but effective way to increase the productivity and to achieve significant cost reductions in this sector.
Besides its application in tools, this technology also has a great potential to improve the performance of the materials used to manufacture transmission elements like, for example, cemented steel. Do not forget that these components are designed to withstand big stresses and, consequently, the behaviour of the material they are made of is crucial to define their performance and reliability. Wear resistance and fatigue life are two parameters that can be significantly improved by means of cryogenic treatments, but the effect in other material characteristics (dimensional stability, heat dissipation, corrosion resistance, etc.) is also beneficial. Apart from the empirical evidences, several studies conducted in recent years confirm the positive effect of these processes in case hardened steels and other materials commonly used in gears and transmission elements.
As happened with other technologies before, the use of cryogenic treatments in these applications has been promoted by its growing success in Motorsports. These processes have become common (especially in North America) because they significantly improve the performance and reliability of clutches, brake discs, springs, engine blocks, cylinder heads, pistons, bearings, crankshafts, connecting rods… and, of course, also transmission elements (gearboxes, differentials, pinions, etc).
The multistage cryogenic treatments are a simple, effective and economical way to increase the performance and reliability of the materials used in these and other areas. Moreover, if they are taken into account from the design phase, these performance improvements can become a valuable tool for achieving significant size and weight reductions in many components.