Meaning
Specialised alloy maintains its hardness and structural stability when exposed to the extreme thermal loads of plastic processing. High-temperature tool steel is used in injection moulding for engineering resins with high melting points like PEEK or PEI. It resists softening and deformation under the pressure and heat of the injection cycle.
The classification stops applying if the operating temperature remains consistently below two hundred degrees Celsius where standard steels suffice.
Thermal Fatigue
Repeated heating and cooling can cause surface cracks known as heat checking in lesser steels. High-temperature tool steel possesses the thermal shock resistance necessary to prevent these defects over long production runs. This property is necessary for maintaining the surface finish of the moulded parts.
Hardness Retention
The addition of elements like tungsten and molybdenum prevents the steel from tempering during use. High-temperature tool steel stays hard enough to resist the abrasive wear of glass fibres often found in high-performance polymers. A moulder using this steel can maintain tight tolerances even after thousands of hours of production.
Processing Difficulty
Fabricating tools from these alloys requires specialized heat treatment and precision grinding. High-temperature tool steel is more expensive than standard grades but necessary for moulding advanced thermoplastic materials.
