Heat treatment is specified for the mold steel and tool application, not selected from a universal recipe. Some plastic-mold steels are supplied pre-hardened; other grades or components may require a separate treatment. The chosen condition can affect hardness, toughness, wear and dimensional stability, so the tool drawing and steel supplier’s technical data should define the requirement.
What an OEM buyer should confirm
- Identify the exact steel grade, component and delivery condition in the approved mold specification.
- Confirm whether additional heat treatment is required or whether the supplied condition is intended for use as delivered.
- If treatment is specified, agree on the required process record and test evidence with the toolmaker, steel supplier and customer.
- Record hardness measurements at the locations and by the method required for the tool; do not substitute a single number for an agreed inspection plan.
- Inspect critical dimensions and finish after the machining and treatment stages that can affect them, using the approved mold drawing as the acceptance basis.
- Keep material identification, heat-treatment records, inspection results and the mold revision together for future maintenance or repair.
Tool-steel suppliers publish grade-specific instructions and explain that heat treatment and dimensional change depend on the selected grade and process. See Uddeholm’s technical guide to steel for molds and ASSAB’s heat-treatment information. These sources support checking the actual steel specification; they are not interchangeable heat-treatment recipes.
For the wider tooling acceptance process, see the injection mold quality checklist and mold manufacturing stages.