Optical Profilometry Replica Metrology Protocol for Mould Cavity Topography
Indirect optical profilometry on elastomeric cavity replicas yields sub-micron texture data while eliminating tool teardown and optical access limits.
Chemical Etching Wear
Meaning
Corrosive degradation of mould surfaces occurs when volatile byproducts from processed polymers react with the steel substrate. Damage from chemical etching wear typically involves the leaching of binder metals or the oxidation of the iron matrix in the tool. It appears as a dulling of polished finishes or a gradual increase in surface roughness that transfers to the moulded part.
The process continues until the corrosive gases are purged or the tool surface is treated.
Volatile Emission
Heat during the plasticizing stage breaks down certain polymers like polyvinyl chloride or flame retardant additives. These reactions result in chemical etching wear when acidic vapours like hydrogen chloride are released. Acidic gas then attacks the grain boundaries of the mould steel.
Surface Damage
Loss of tool luster indicates the early stages of the corrosion process. Pitting from chemical etching wear becomes visible under magnification as the metal is eaten away. This change in texture increases the friction between the part and the tool.
Protective Coating
Stainless steel alloys or specialized platings like chrome provide a barrier against chemical attack. Resistance to chemical etching wear is improved by using nickel based coatings in fluoropolymer processing. Regular cleaning of the mould also removes the acidic residue before it can damage the surface.