Valve Spring Failure
A valve spring’s loss of performance and ultimate failure is caused by a fatigue phenomenon due to very small stress cracks on the surface of the valve spring which will propagate thru the valve spring wire, this fatigue will result in fracturing the valve spring.
There are several surface treatment technologies that have been developed to address the valve spring performance issue in hi-performance race engine applications.
Vibratory finishing methods are employed to modify the surface texture of a valve spring. This process will decrease the size of the valve spring’s surface defects, thus decreasing the number of fatigue areas. A typical vibratory process consists of a container that has abrasive media, water and a finishing compound that is circulated at low speeds. The valve springs are immersed in this mixture for a predetermined amount of time in order to achieve the correct surface finish.
Sometimes a chemical additive is used to accelerate the abrasion of the valve spring surface, thus allowing a shorter processing time.