Meaning
Metal surface durability against adhesive wear prevents pickup and material transfer during high load sliding contact. Tooling components experience galling resistance when nitriding or surface coatings reduce friction under extreme pressure. Core pins and slide faces maintain dimensional integrity when this property restrains micro welding between mating tool steels.
Tool maintenance schedules dictate surface treatments before abrasive wear compromises cavity geometry.
Surface Hardening
Nitriding treatments establish nitrogen diffusion layers that elevate hardness profiles across cavity inserts and moving cores. Hardened substrates prevent microscopic asperities from interlocking under clamping tonnage during high speed injection cycles. Elevated surface hardness suppresses adhesive transfer when virgin engineering thermoplastics undergo high shear sliding against steel walls.
Process engineers specify case depth parameters according to injection pressure demands and expected cycle frequencies.
Tooling Geometry
Clearance tolerances dictate whether sliding interfaces experience severe adhesive wear or stable sliding contact during core plate actuation. Sharp transitions concentrate mechanical stress and accelerate localized breakdown of protective oxide layers on moving slides. Correct draft angles minimize prolonged friction against cavity walls during ejection phases.
Toolmakers alter surface finishes from directional grinding marks to isotropic textures to disrupt the metal contact geometry that initiates galling.
Regrind Economics
Thermal degradation history alters polymer melt rheology and increases abrasive particle generation inside high output runners. Virgin resin processing maintains predictable friction coefficients whereas regrind incorporation accelerates adhesive wear on unlubricated shut off surfaces. Injection molders balance regrind percentages against tool life expectancy to avoid unexpected maintenance downtime.
Elevated regrind levels demand upgraded surface treatments on moving components to preserve long term operational reliability.
