Corrosion protection, wear resistance, appearance — finishing is specified on the same quote as the machining, so the part arrives done, not almost done.
| Finish | Base metals | Use it for |
|---|---|---|
| As machined | All | Fixtures, internal parts, prototypes — clean tool finish, deburred edges, no coating. The default if the drawing says nothing. |
| Bead blasting | Aluminum, stainless | A uniform matte look that hides tool marks. Usually the step before anodizing on cosmetic parts. |
| Anodizing (clear / color) | Aluminum | Corrosion resistance and color — the standard finish for aluminum housings and consumer-facing parts. |
| Hard anodizing | Aluminum | Wear surfaces, sliding parts, threads that see repeated assembly. Thicker and harder than cosmetic anodize. |
| Powder coating | Steel, aluminum sheet | Tough, even color on enclosures, frames, and guards. The workhorse finish for fabricated parts. |
| Zinc plating | Mild steel | Low-cost corrosion protection for brackets and hardware that live indoors. |
| Nickel plating | Steel, brass, copper | Corrosion resistance plus a bright, hard surface — common on fittings and wear parts. |
| Black oxide | Steel | A thin black conversion coat for tooling and fasteners — mild protection, no dimensional change. |
| Passivation | Stainless | Restores full corrosion resistance after machining — specify it for medical and food-contact stainless. |
| Brushing / polishing | Stainless, aluminum | Directional or mirror cosmetic surfaces, and hygienic contact faces on food-line parts. |
| Laser marking | Most metals | Part numbers, logos, scales, and serials — permanent, crisp, and cheap to add to any of the above. |
Threads, bores, and datum faces often must stay uncoated. Call them out on the drawing and they are masked before coating — quietly critical on anodized and powder-coated parts.
Coatings have thickness. Tight fits are machined to allow for it, which is why the finish belongs on the RFQ — not discovered after the parts are cut.
Name a RAL or Pantone reference for painted and anodized parts. "Black" spans a dozen finishes; a number lands the one you meant.
Put the finish on the RFQ and the quote covers the whole part — machined, coated, masked where it matters, and inspected after.