Precision Grinding — design guidelines
Grinding is a finishing operation, not a shaping one. It exists to take a part that is already close to size and bring one or two surfaces into a tolerance band that cutting cannot reach. Design for it by leaving stock and by making the surface reachable by a wheel.
Constraints specific to this process
These are the limits that come from this process in particular. The general rules on wall thickness, corner radii and hole depth apply on top of them.
| Parameter | Design to thisNo surcharge, no discussion needed | We can reachAchievable, but affects price or lead time | Where the limit comes from |
|---|---|---|---|
| Grinding allowance | 0.2 – 0.3 mm | 0.1 mm minimum | The wheel has to remove enough to clear the previous operation's marks and any heat-treat distortion. Less than 0.1 mm and a low spot may not clean up at all. |
| Wheel access at a shoulder | Relief groove per DIN 509 | 0.5 mm corner radius | A grinding wheel cannot produce a sharp internal corner. Without a relief groove the wheel either leaves stock in the corner or digs into the shoulder face. |
| Achievable tolerance | ±0.005 mm | ±0.002 mm | ±0.002 mm requires a temperature-stabilised room and measurement at 20 °C. We can hold it, but the part has to soak before inspection and that extends the lead time. |
| Surface finish | Ra 0.4 | Ra 0.1 with honing | Ra 0.4 comes off a standard wheel. Below Ra 0.2 we move to honing or lapping, which is a separate operation with its own fixture. |
What we see go wrong most often
Recurring issues on the drawings that reach us. None of them are hard to avoid once you know to look for them.
- Ordering grinding on a soft material. Aluminium and copper load the wheel instead of being cut by it — for those, a fine turning or milling pass gives a better result.
- Specifying a ground finish on every surface. Grinding is priced per surface — naming the two that actually seal or locate is usually a large saving.
General machining rules
The numbers that apply across every cutting process — wall thickness, radii, holes, threads, tolerances and cost drivers.
- Wall thickness
- Internal corner radii
- Holes and threads
- Pockets, cavities and undercuts
- Tolerances, text and surface callouts
- What actually drives the price
Every quotation includes a manufacturability review against these rules. If something in your model falls outside them, we tell you before you commit, not after the first article fails.
Not sure whether your part clears these limits?
Send the STEP file. A manufacturing engineer marks up anything that will be difficult and returns it with the quotation — no charge, no obligation.