Areal Surface Texture Parameter Measurement in Micro Injection Mould Cavities
Areal surface metrology in micro-cavities requires non-contact optical instruments with matched bandwidth filters to verify steel texture and polymer replication.
Nickel Phosphorus Coating
Meaning
Autocatalytic chemical plating deposits uniform metallic alloys onto metallic substrates without applying electrical current. Tooling engineers specify nickel phosphorus coating to protect mould steel inserts against corrosive resin off-gassing and abrasive filler wear. High phosphorus content provides amorphous metallurgical structure with exceptional corrosion resistance against fluoropolymer degradation products.
Datasheet coating hardness values increase significantly after post-plate heat treatment processes.
Chemical Deposition
Electroless plating baths reduce nickel ions using sodium hypophosphite agents onto activated steel surfaces. Uniform bath chemistry deposits consistent coating thickness across internal threads and deep cavity slots. Precise temperature control prevents phosphorus composition gradients from forming along complex mould geometries.
Deposit thickness control eliminates post-plating grinding operations on precision core pins.
Hardness Enhancement
Heat treatment at elevated temperatures precipitates nickel phosphide phase structures within the amorphous matrix. Thermal hardening increases surface hardness from four hundred Vickers to over nine hundred Vickers. High hardness protects core pins against scratching from glass reinforced polyamides during injection cycles.
Un-tempered coatings maintain lower hardness but offer superior ductililty under cyclic mechanical loading.
Mould Longevity
Corrosion barrier protection prevents pitting from aggressive flame retardant additives in engineering resins. Low surface energy coatings reduce polymer adhesion and lower required part ejection forces. Plating degradation triggers micro-flaking that contaminates moulded medical components, dictating strict coating strip and re-plate cycles.