# Ground & Lapped Precision Parts — CNC Machined to Drawing

> Sinbo Precision (sinbo-machining.com) machines 22 ground & lapped parts to customer drawing in Dongguan, China — quotation within 48 hours, first prototypes in 7–15 days, from 1 piece. IATF 16949 & ISO 9001:2015 certified.

The grinding cell is where tolerances get finished: centerless grinding for pins, rollers and shafts at roundness ≤0.002 mm, double-disc grinding for plates and spacers at parallelism ≤0.005 mm, and single-side lapping for seal faces at Ra 0.1. Hardened 100Cr6-equivalent, 416, 42CrMo4 and stainless are daily stock.

## 22 Ground & Lapped Precision Parts We Machine

- **Ground needle** — Ø0.5–8 mm, roundness ≤0.002 mm.
- **Lapped plunger** — Ra 0.1, diameter ±0.001 mm option.
- **Ground punch** — hardened 58–62 HRC, cutting-edge prep.
- **Ground bore bushing** — ID H6/H7, hardened.
- **Wear plate, double-disc ground** — parallelism ≤0.005 mm, both faces.
- **Precision spacer, double-disc ground** — thickness ±0.002 mm, batch-uniform.
- **Lapped valve plate** — flatness ≤0.002 mm.
- **Lapped seat** — seal faces Ra 0.1.
- **Ground anvil** — face hardened + ground.
- **Ground measuring tip holder** — tip-seat concentricity ≤0.003 mm.
- **Setting disc** — ground both faces, calibrated thickness report.
- **Centerless ground roller** — roundness ≤0.002 mm, length batch-uniform.
- **Centerless ground shaft** — Ø0.5–50 mm, h5/h6.
- **Centerless ground pin** — diameter band ±0.002 mm batch-consistent.
- **Ground slide plate** — way-facing geometry.
- **Ground way insert** — gib-taper options.
- **Knife-edge guide, ground** — edge radius controlled.
- **Double-disc ground disc** — Ø up to 200 mm, flatness ≤0.005 mm.
- **Ground faced ring** — faced both sides, ID/OD concentric.
- **Lapped piston** — pump and compressor duty.
- **Lapped sleeve, ID** — bore Ra 0.1.
- **Ground V-block insert** — angle ±30 arcsec option.

## Typical Materials & Tolerances

| Parameter | Value |
|---|---|
| Metals | Stainless 303/304/316/316L/416/17-4 PH · brass CW617N, DZR CW602N, CuZn39Pb3 · aluminum 6061/7075/6082 · steel 1018/1045/42CrMo4/16MnCr5 |
| Plastics | PEEK · PTFE · POM (Delrin) · nylon · PVDF · polycarbonate |
| Tolerances | ±0.005 mm on critical diameters · DIN ISO 2768-mK general · ground features ±0.002 mm |
| Surface | Ra 0.8 standard machined finish · Ra 0.4 / Ra 0.2 ground · Ra 0.1 lapped |
| Finishes | nickel / zinc / hard chrome / black oxide / anodizing / PVD via audited partners |
| Documentation | EN 10204 3.1 material certificates · FAI · PPAP Level 3 (automotive) · full dimensional report |
| Order range | 1-piece prototypes · batch 100–20,000+ · 2.6 million parts/month capacity |
| Lead time | quotation within 48 hours · first prototypes 7–15 days |

## Related Pages

- [Japan machine tool outsourcing](https://www.sinbo-machining.com/case/jp-machine-tool-outsourcing/)
- [Taiwan machine tool parts](https://www.sinbo-machining.com/case/tw-machine-tool-parts/)
- [Steel parts](https://www.sinbo-machining.com/products/materials/steel/)

**Request a quote:** send your drawing to leo.pan@sinbo-machining.com — quotation within 48 hours, no minimum order for prototypes.

Last updated: 2026-09-27