Home / Materials & Heat Treatment
Materials & Heat Treatment
Select fixture materials by function: rigid bodies, wear-resistant locating surfaces, tough clamping elements. Hardness and grindability matter more than absolute strength for most parts.
Carbon Steels
| Grade (CN / EN) | AISI / approx. | Typical use |
|---|---|---|
| Q235 / S235 | A36 | Welded bodies, brackets, base plates |
| 45# / C45 | 1045 | Bodies, clamp plates, pins; hardenable (quench 45–52 HRC) |
| 40# / C40 | 1040 | General fixture structural parts |
Alloy Steels
| Grade (CN / EN) | AISI / approx. | Typical use |
|---|---|---|
| 40Cr / 41Cr4 | 5140 | Locating pins, high-strength clamps, quenched ~52 HRC |
| 20Cr / 20Cr4 | 5120 | Case-hardened pins and bushings (surface 58–62 HRC) |
| 42CrMo / 42CrMo4 | 4140 | High-strength studs, heavy clamp screws |
Spring Steel
| Grade | AISI / approx. | Typical use |
|---|---|---|
| 65Mn / C65 | 1566 | Clamp springs, spring washers |
Tool & Die Steels
| Grade | AISI / approx. | Typical use |
|---|---|---|
| T8A / T10A | W1 | Locators, rest pads, small parts needing 58–62 HRC |
| Cr12MoV | D2 | Wear-resistant gauge plates, dies, hardened 58–62 HRC |
| W6Mo5Cr4V2 (M2) | M2 | Cutting edges, boring bars, tool steel guides |
Cast Iron
| Grade | approx. | Typical use |
|---|---|---|
| HT200 | Class 30 | Fixture bodies, jig bodies (rigid, damps vibration, machinable) |
| HT250 | Class 35 | Heavier bodies where higher strength is needed |
Aluminium
| Grade | Note | Typical use |
|---|---|---|
| 6061-T6 | Good strength & machinability | Light fixtures, inspection fixtures, prototyping |
Heat Treatment Guide
| Process | Typical hardness | Typical use |
|---|---|---|
| Normalizing | — (structure only) | Bodies, improving machinability and stability |
| Quench & temper | 28–32 HRC | Medium-strength parts: clamp plates, pins (C45, 40Cr) |
| Hardening & tempering | 45–55 HRC | Locating pins, wear surfaces |
| Carburizing | 58–62 HRC (case) | Low-carbon steel pins and bushings (20Cr) |
| Nitriding | HV 900+ surface | High-precision parts, minimal distortion |
Material by Component
| Component | Recommended |
|---|---|
| Fixture / jig body | C45 (normalized) or HT200 cast |
| Clamp plate, clamp screws | C45, 40Cr |
| Locating pin | 40Cr or T10A, hardened & ground |
| Drill jig bushing | 20Cr carburized or T10A (60 HRC) |
| Spring | 65Mn |
| Light fixture | 6061-T6 aluminium |
Hardness is measured on the Rockwell C scale (HRC) for steels. Grind after hardening to keep locating surfaces accurate and wear-resistant.
Hardness Scale (HRC)
Hard case treatments sit above 55 HRC; fixture bodies are usually used as-normalized.
Hardenability (Jominy)
Heat Treatment Routes
Choose the route by component function: bodies stay soft, locating parts get hard and ground.
Case Depth
Carburized case: hard, wear-resistant surface over a tough, impact-resistant core.