Mechanical finishing & post-processing · finish comparison
Lapping vs Surface Grinding
Lapping and Surface Grinding are both mechanical finishing finishes; ground is the lower-cost option ($$$).
Lapping
Mechanical finishing · $$$$
Lapping is a precision loose-abrasive process used to improve flatness, parallelism, and very fine roughness.
Surface Grinding
Mechanical finishing · $$$ · instant quote
Surface grinding uses a bonded abrasive wheel to generate precise flat surfaces.
When to choose which
Choose Lapped
Choose Lapped when lower Ra and tighter flatness are required.
- Achieves Ra 0.01–0.10 µm (0.4–4 µin)
- Improves flatness and parallelism
- Produces high bearing area
Choose Ground
Choose Ground when faster stock removal and Ra above 0.2 µm are acceptable.
- 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
- Ground is the lower-cost option ($$$).
Scores side by side
Each score is 0–100 against every finish in this catalog. Corrosion is derived from salt-spray test duration and surface hardness from the finish layer's Vickers hardness where a measured figure exists; a finish that leaves the base metal's own surface is not rated for hardness. Cosmetic, lubricity and cost are FabDigit's engineering assessment. Scores and typical figures are screening data, not matched side-by-side tests or service-life rankings; ASTM B117 is a controlled salt-fog method, not a field-life prediction.
| Score | Lapped | Ground |
|---|---|---|
| Corrosion resistance | 0 Minimal | 0 Minimal |
| Surface hardness / wear | — — | — — |
| Cosmetic quality | 70 Very good | 35 Fair |
| Lubricity | 30 Low | 20 Low |
| Cost | 70 $$$$ | 45 $$$ |
Key numbers
| Property | Lapped | Ground |
|---|---|---|
| Thickness | 0 µm | 0 µm |
| Electrical | Unchanged | Unchanged |
| Relative cost | High ($$$$) | Premium ($$$) |
| Added lead time | 3–10 working days | 2–7 working days |
| RoHS | Compliant | Compliant |
| Instant quote | On request | 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 | Lapped | Ground |
|---|---|---|
| Ceramic | Yes | With care |
| Stainless Steel | Yes | Yes |
| Steel | Yes | Yes |
| Aluminum | With care | With care |
| Brass | With care | With care |
| Copper Alloy | With care | With care |
| Magnesium Alloy | With care | With care |
| Titanium | With care | With care |
| Zinc Alloy | With care | With care |
Lapped vs Ground — frequently asked
What is the difference between Lapped and Ground?
Lapping and Surface Grinding are both mechanical finishing finishes; ground is the lower-cost option ($$$).
When should I use Lapped instead of Ground?
Choose Lapped when lower Ra and tighter flatness are required. Conversely: choose Ground when faster stock removal and Ra above 0.2 µm are acceptable.
Is Lapped or Ground cheaper?
Ground is the lower-cost finish ($$$ against $$$$ for Lapped) 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.