Heat Treating Services
Resolute Precision Manufacturing coordinates heat treating of precision machined components through our qualified outside heat treat network. From quench and tempering to stress relieving, annealing, carburizing, and through-hardening, we manage the complete process and deliver heat treated parts with certification documentation. One purchase order covers machining and heat treatment. Request a QuoteWhy Heat Treatment Matters for Precision Parts
Heat treatment changes the mechanical properties of metal components by increasing hardness and strength, relieving internal stresses, or establishing a specific microstructure for the application. The right heat treatment is as critical to component performance as the geometry itself. For example, a 4140 steel shaft can achieve different strength and hardness characteristics depending on its heat treatment and final condition.
The challenge with heat treating CNC machined parts is managing dimensional distortion. Quenching, in particular, can cause shafts to bow, bores to change diameter, and thin sections to warp. Controlling distortion requires an understanding of the interaction between part geometry, material, heat treatment process, and subsequent grinding or finishing requirements.
Our team coordinates heat treatment with your machining requirements, helping plan stock allowances and finishing operations to achieve the required final dimensions.
Heat Treat Processes We Coordinate
We coordinate the following heat treating processes through our qualified supplier network:
Quench and temper (Q&T) — Hardening followed by tempering to achieve the specified hardness, strength, and toughness.
Stress relieving — A controlled thermal cycle to reduce machining-induced residual stresses while minimizing changes in hardness.
Annealing — Heating and controlled cooling to soften material, improve machinability, or prepare components for subsequent processing.
Normalizing — Heating above the critical temperature followed by air cooling to refine grain structure and improve material uniformity.
Carburizing and case hardening — Enriching the surface with carbon and subsequently hardening it to provide a wear-resistant case with a tougher core.
Through-hardening — Hardening the full cross-section of a component for applications requiring hardness throughout the material.
Design Considerations for Heat Treated Parts
Our team can advise on important design and manufacturing considerations during the quoting process:
Material selection — Choosing the appropriate steel grade to meet the required hardness, strength, wear resistance, and toughness.
Stock allowance — Planning machining allowances for post-heat-treatment grinding and finishing on critical dimensions.
Masking and selective hardening — Protecting threads, precision bores, or other specified areas from hardening where required.
Drawing specifications — Clearly defining hardness range, case depth, heat treatment process, and applicable standards on the engineering drawing.
Planning these requirements early helps reduce the risk of dimensional issues and additional finishing operations when heat treating CNC machined parts.
Specifications
| Materials | All hardenable steels — 1045, 4140, 4340, 8620, D2, H13, 17-4 PH stainless steel, and others |
| Hardness Range | Rc 20–65 depending on material, process, and specification |
| Specifications | AMS 2759 series, ASTM A255, MIL-H-6875, and customer-proprietary specifications |
| Case Depth (Carburize) | 0.010″ to 0.060″ effective case depth, per drawing specifications |
| Documentation | Heat treatment certifications, hardness test reports, and case depth reports provided with finished parts |
| Turnaround | Typically 1–2 weeks for standard processes; expedited service available upon request |
| Certifications | ISO 9001:2015 |
Design Considerations for Heat Treated Parts
Our engineers can advise on the following heat treatment design considerations during your quoting process:
Material selection — choosing the right steel grade for the target hardness and toughness requirement
Stock allowance — leaving machining allowance for post-heat-treat grinding on critical dimensions
Masking and selective hardening — protecting threads and precision bores from case hardening where required
Print callout — specifying hardness range, case depth, and heat treat specification on the drawing
Frequently Asked Questions
How much dimensional change should I expect after heat treatment?
Distortion from quench hardening is geometry and material dependent. Thin sections and long slender parts distort more. As a general rule, allow 0.003″ to 0.010″ stock on OD diameters that require grinding after heat treat. We advise on stock allowance as part of the quoting process.
Can RPM selectively harden only certain surfaces on a part?
Yes. Through masking with copper plating or mechanical shields, we can protect specific features from case hardening threads, precision bores, and ground surfaces are commonly masked during carburizing and nitriding processes.
What documentation does RPM provide with heat treated parts?
We provide the heat treater’s certification of conformance, hardness test records (Rockwell or Brinell), case depth measurements for carburized parts, and temperature charts for critical processes. All documentation is referenced to the specific lot and part number.
Can RPM handle stainless steel heat treatment?
Yes. We coordinate 17-4 PH stainless heat treatment to H900, H1025, H1075, and other aging conditions per AMS 5604. We also coordinate solution annealing of 316 and 304 stainless for stress relief and corrosion resistance optimization.