06.1 · Grinding Machines
Grinding Fundamentals
Grinding uses an abrasive wheel to remove tiny amounts of material — typically 0.01–0.05 mm per pass. It's the process that turns a turned or milled part into a precision part: tight tolerances, fine surface finish, and hardened materials.
Why Grind?
- Tolerance: Grinding holds ±0.002–0.005 mm, better than turning or milling.
- Surface finish: Ra 0.1–0.4 µm is typical.
- Hardened materials: You grind hardened steel (50–65 HRC) after heat treat — turning can't cut it.
Types of Grinders
| Grinder | What it does | Typical parts |
|---|---|---|
| Surface grinder | Flat horizontal surface | Die sets, tooling, flat plates |
| Cylindrical grinder | OD of rotating part between centers | Shafts, pins, bearing journals |
| Internal grinder | ID of a hole | Bearing races, bushings |
| Centerless grinder | Part rests on a blade, no centers | High-volume pins, shafts, bars |
Grinding leaves residual stresses and heat. Burn, chatter, and thermal damage are real problems. Use proper wheel selection, dress the wheel regularly, and use ample coolant. Never take a heavy cut — grinding is a finishing operation, not roughing.