Valve spring stress relieving
Valve Spring Stress Relieving Process
The Valve spring story started with GM back in 1997 after the purchase of an electric conveyer oven. The system and process adopted offered a total cycle time from coiler to the end of the conveyor belt in 9 minutes as opposed to 35 minutes with the original furnace. Tests were conducted on the tensile strength, hardness profiles, and residual stress levels with the use of x-ray diffraction. Relaxation and fatigue cycling confirmed that the spring processed through the Pyro oven performed as well as those that processed through the conventional oven. The Pyro afforded a much shorter pre-heat time of only 10 minutes as compared to conventional 45 minutes, which correlates with a decreased production time with the Pyro.
This reduction resulted in an increase of approximately 3 hours of more production time for a five-day workweek. In other words, the customer gained approximately 4 more weeks of production per year with a substantial reduction in pre-heat savings. The reduction in size also allows for greater manufacturing accessibility to other machinery. There are also some substantial energy savings with the Pyro electric oven as opposed to the gas-powered oven.