Hardness is often mentioned in shaft and pin RFQs, but not every part needs a strict hardness range. For custom steel shafts, pins, bushings and linkage components, hardness should match load, wear, impact, mating parts and service environment. Over-specifying hardness can increase process complexity, while under-specifying it may reduce service life.
- Hardness matters most when the part experiences wear, sliding contact, impact or repeated load.
- General locating pins or simple rods may not need special heat treatment if load is moderate.
- Medium carbon steel or alloy steel may be selected when heat treatment is required.
- Surface hardness and core toughness should be considered differently for some mechanical parts.
- Heat treatment can change dimensions, so final machining or inspection planning may be needed.
- The drawing should state hardness range, testing position and standard when the requirement is critical.
- Surface treatment should be planned after heat treatment unless the process route requires otherwise.
- Buyers should explain the working condition and mating parts so the supplier can judge a suitable material and process.