Meaning
Tooling steel alloys with high chromium content provide the structural basis for injection mould cores and cavities exposed to corrosive resins. Martensitic stainless steels designated under aisi 420 stainless contain twelve to fourteen percent chromium, delivering moisture protection without requiring surface plating. Mould tooling fabricated from this grade resists pit formation caused by off-gassing during processing of polyvinyl chloride or flame-retardant polymers.
Polishing Response
Lapping operations on hardened tool steel determine the optical surface quality of moulded parts. High micro-cleanliness in aisi 420 stainless prevents micro-scratches during diamond polishing.
Corrosion Resistance
Chemical attack from degraded polymer volatiles causes pitting along parting lines during long production runs. Standard carbon steels require nickel plating to survive humid shop environments or acidic resin byproducts, whereas stainless alloys build an inherent oxide layer. Heat-treated aisi 420 stainless maintains surface integrity under acidic outgassing, eliminating plating flaking defects in medical device housings.
Water channels inside the mould frame remain free of rust scale over years of operation, preserving predictable heat transfer rates across seasonal ambient humidity shifts.
Thermal Recovery
Heat extraction rates through mould walls govern cycle times in thick-walled section moulding. Thermal conductivity in steel alloys determines how rapidly cavity surfaces cool after melt injection. Using aisi 420 stainless balances structural strength under high clamping forces against thermal dissipation needs, preventing localized heat sinks from extending cooling cycles.
