Meaning
Engineering assessment methods determine the pressure at the interface of two metal surfaces within a tool. Applying a contact stress calculation ensures that the mould base can withstand the clamping force without permanent deformation. These values determine the size of support pillars and the thickness of the cavity plates.
Engineers use these results to prevent surface hobbing or tool failure during high pressure injection.
Interface Pressure
Mapping the force across the parting line identifies areas where the steel might collapse under load. A contact stress calculation shows if the land area is large enough to support the tonnage of the press. If the pressure exceeds the yield strength of the mould steel, the tool will suffer from premature wear.
Tool Longevity
Hardened inserts must resist the constant pounding of the moulding cycle without cracking. Using a contact stress calculation allows designers to select the appropriate grade of tool steel and heat treatment. This preparation prevents the formation of stress cracks that would otherwise shorten the life of the mould.
Calculation Boundary
Estimations of stress become less accurate if the mould plates are not perfectly flat or if the machine platen is warped. Once the tool is in the press, thermal expansion can change the actual pressure seen at the parting line. Actual measurements often vary from the theoretical values found during the design phase.
