• Business Envoy

Stripper Springs

Metals springs used as strippers in press tools get a permanent set in a very short time. Due to their inherent property of low permanent set, whereas, `polyurethane? stripper springs help press tools designers to overcome this problem. Additionally, with `polyurethane `stripper springs much higher loads per square mm can be achieved with lesser compression. This results in great space saving in the press tool compared to metal springs. 'Polyurethane' is resistant to almost all types of lubricants and oils used in metal forming. Hence its service life exceeds that of conventional rubber and metal springs. Relationship between compressibility and strokes per minute: when the polyurethane spring is deformed, heat is generated through internal friction (hystersis). This heat accelerates the failure of the spring. The amount of heat generated is directly proportional to the frequency of strokes and the compression. So, strict attention needs to be given to keep the compression at the minimum, especially when the frequency of strokes exceeds 70 strokes per minute. As a general rule, it is safe to select a spring size that maintains a maximum compressibility at 25% for processes, requiring around 70 strokes per minute. If these conditions are met then the durability of the polyurethane spring exceeds the durability of metal springs.