Matching Tool Steel Selection to Initial Production Commitments
Match tool steel hardness and chemistry directly to committed shot counts and resin abrasiveness to prevent premature cavity failure and tooling cost overruns.
Bohler M390
Meaning
Premium martensitic stainless steel produced through powder metallurgy offers extreme wear resistance and high corrosion resistance for demanding tooling components. The steel known as bohler m390 contains high levels of carbon, chromium, vanadium, and molybdenum to generate a high volume of hard carbides. This microstructural design protects the injection mould inserts from abrasive wear when processing highly filled or corrosive thermoplastic resins.
The alloy is typically used for screws, non-return valves, and gate inserts.
Powder Metallurgy
Gas atomization of the liquid alloy produces fine powder that is compacted under high pressure and temperature to ensure a homogeneous microstructure. This processing prevents the carbide segregation that often occurs in conventionally cast steels, resulting in uniform mechanical properties in all directions. The uniform distribution of vanadium and chromium carbides improves the toughness and polishability of the tool steel.
Wear Resistance
Fine carbide distribution provides exceptional resistance to abrasive wear from glass fibers and mineral fillers. Because the carbides are small and evenly dispersed, they prevent the resin from eroding the metal matrix surrounding them. This resistance maintains the sharp edges of gate inserts over long production runs, which prevents the formation of flash on the moulded parts.
Tooling Application
High corrosion resistance against acidic byproducts of outgassing resins protects the polished cavity surfaces from deterioration. This performance reduces the need for frequent repolishing of the mould cavity, which keeps maintenance costs low and maintains dimensional accuracy of the parts. Moulds constructed with these inserts run continuously for millions of cycles without losing their high-gloss surface finish.
Preventing cavity deterioration is especially valuable when moulding optical lenses or medical devices where surface defects cause immediate rejection of the batch.