Sequence in heat treatment: what is the rule?

Rough-machine, heat treat, then finish-grind or finish-machine. Distortion during heat treatment cannot be machined away afterwards.

Uniform sections in heat treatment: what is the rule?

Avoid big changes in thickness and sharp inside corners. They crack or warp in the quench.

Specify the result in heat treatment: what is the rule?

State grade, hardness and tolerance (for example 58–62 HRC) and case depth if surface-hardened. It is what the shop is tested against.

Slender parts in heat treatment: what is the rule?

Long thin parts distort; ask about fixtures or straightening. Quenching bends long parts.

Certificates in heat treatment: what is the rule?

Ask for a hardness test report if the part is critical. It is proof of the result.

Heat treatment: design rules

Changing the properties of metal by controlled heating and cooling (hardening, tempering, annealing, case hardening).

Typical tolerance

Parts distort; leave about 0.1–0.3 mm for finish grinding on critical surfaces.

Files to send

Drawing with material grade, required hardness (for example HRC), case depth and which surfaces stay soft.

Common materials

Tool and alloy steels, carbon steels, stainless grades that can be hardened.

The rules, with reasons

Sequence. Rough-machine, heat treat, then finish-grind or finish-machine. Why: Distortion during heat treatment cannot be machined away afterwards.
Uniform sections. Avoid big changes in thickness and sharp inside corners. Why: They crack or warp in the quench.
Specify the result. State grade, hardness and tolerance (for example 58–62 HRC) and case depth if surface-hardened. Why: It is what the shop is tested against.
Slender parts. Long thin parts distort; ask about fixtures or straightening. Why: Quenching bends long parts.
Certificates. Ask for a hardness test report if the part is critical. Why: It is proof of the result.

Before you ask for a quote

Material grade
Required hardness and depth
Quantity
Distortion tolerance
Certificates

Common mistakes

Finishing before heat treatment
Sharp corners on hardened parts
No hardness specification

Request a quote Find manufacturers

Typical rules of thumb, not a guarantee. The manufacturer's own design guidelines override them: ask for them and check your design against both before ordering.