Mechanical finishing & post-processing · finish comparison
Polishing vs Surface Grinding
Polishing and Surface Grinding are both mechanical finishing finishes; polished resists corrosion better.
Polishing
Mechanical finishing · $$$ · instant quote
Mechanical polishing progressively removes surface peaks and scratches to produce a smooth glossy surface.
Surface Grinding
Mechanical finishing · $$$ · instant quote
Surface grinding uses a bonded abrasive wheel to generate precise flat surfaces.
When to choose which
Choose Polished
Choose Polished when appearance rather than precision geometry is primary.
- Reduces Ra to about 0.1–0.8 µm (4–32 µin)
- Improves cleanability
- Creates a glossy cosmetic surface
Choose Ground
Ground is the pick when its strengths below matter more than Polished's.
- Can hold about ±0.005 mm on suitable work
- Produces Ra about 0.2–1.6 µm (8–63 µin)
- Creates flat parallel mating faces
What the numbers say
- Polished resists corrosion better.
- Ground is the lower-cost option ($$$).
Scores side by side
Each score is 0–100 against every finish in this catalog. Corrosion is derived from salt-spray test duration and surface hardness from the finish layer's Vickers hardness where a measured figure exists; a finish that leaves the base metal's own surface is not rated for hardness. Cosmetic, lubricity and cost are FabDigit's engineering assessment. Scores and typical figures are screening data, not matched side-by-side tests or service-life rankings; ASTM B117 is a controlled salt-fog method, not a field-life prediction.
| Score | Polished | Ground |
|---|---|---|
| Corrosion resistance | 8 Minimal | 0 Minimal |
| Surface hardness / wear | — — | — — |
| Cosmetic quality | 82 Very good | 35 Fair |
| Lubricity | 20 Low | 20 Low |
| Cost | 55 $$$ | 45 $$$ |
Key numbers
| Property | Polished | Ground |
|---|---|---|
| Thickness | 0 µm | 0 µm |
| Electrical | Unchanged | Unchanged |
| Relative cost | Premium ($$$) | Premium ($$$) |
| Added lead time | 2–7 working days | 2–7 working days |
| RoHS | Compliant | Compliant |
| Instant quote | Yes | Yes |
Bold marks the side that is ahead on a row where more (or less, for cost and lead time) is better. Ranges are the typical specification window; the drawing call-out fixes the class.
Which materials take each finish
| Material family | Polished | Ground |
|---|---|---|
| Aluminum | Yes | With care |
| Brass | Yes | With care |
| Copper Alloy | Yes | With care |
| Stainless Steel | Yes | Yes |
| Steel | Yes | Yes |
| Ceramic | — | With care |
| Magnesium Alloy | With care | With care |
| Polymer | With care | No |
| Titanium | With care | With care |
| Zinc Alloy | With care | With care |
Polished vs Ground — frequently asked
What is the difference between Polished and Ground?
Polishing and Surface Grinding are both mechanical finishing finishes; polished resists corrosion better. Ground is the lower-cost option ($$$).
When should I use Polished instead of Ground?
Choose Polished when appearance rather than precision geometry is primary.
Is Polished or Ground cheaper?
Ground is the lower-cost finish ($$$ against $$$ for Polished) among the finishes FabDigit quotes. Both are priced per part with a lot minimum; the exact figure appears on the instant quote once the part is uploaded.