What the machines, the stock and the inspection can hold
The numbers below are the ones we quote against. Where a value depends on your geometry, it says so — a capability sheet that promises everything is a sales document, not a spec.
Eight plastics, seven metals, stocked in the region
Machinability is graded for a prototype shop, not for a datasheet. If a grade is missing, send the datasheet — we confirm stock before quoting.
| Material | Typical use | Machinability | Notes |
|---|---|---|---|
| ABS | Housings, brackets, enclosures | Good | Impact resistant; bonds and paints well. |
| PC | Transparent covers, guards, lenses | Fair | Tough but prone to stress cracking; anneal after machining. |
| PMMA | Light guides, display windows | Good | Polishes to optical clarity; can craze if coolant is wrong. |
| PA | Gears, bushings, wear strips | Fair | Absorbs moisture; dimensions move after machining. |
| POM | Bearings, rollers, precision slots | Excellent | Dimensionally stable, low friction; difficult to bond. |
| PP | Chemical tanks, living hinges | Fair | Chemically resistant; soft and gummy to cut. |
| PEEK | High-temp insulators, seals | Fair | Needs sharp tooling and slow feeds; expensive stock. |
| TPU | Gaskets, bumpers, grips | Difficult | Flexible; needs fixture support and a sharp, cold cut. |
| Material | Typical use | Machinability | Notes |
|---|---|---|---|
| Al 6061 | Enclosures, heat sinks, fixtures | Excellent | Default alloy; anodises to a consistent colour. |
| Al 7075 | Aerospace brackets, robot links | Good | High strength; less corrosion resistant than 6061. |
| SS 304 | General brackets, food-contact parts | Fair | Work-hardens; sharp tools and constant feed required. |
| SS 316 | Medical, marine, chemical parts | Fair | Better chloride resistance; gummier than 304. |
| Brass | Connectors, RF parts, inserts | Excellent | Free machining; watch dezincification in wet service. |
| Copper | Busbars, heat spreaders, RF shielding | Good | Soft and sticky; burrs need attention. |
| Titanium (Grade 5) | Lightweight structural parts | Difficult | Low thermal conductivity; slow speeds and high tool wear. |
Stock is held as plate, bar and rod. Material certificates are available for every lot on request; customer-supplied stock is inspected and photographed before cutting.
The default is 2768-m. The exceptions are agreed first.
Every tight callout is tied to a datum scheme and a measurement method before production. That is what makes the number repeatable.
| Nominal range | 2768-f | 2768-m |
|---|---|---|
| 0.5 – 3 | ±0.05 | ±0.10 |
| 3 – 6 | ±0.05 | ±0.10 |
| 6 – 30 | ±0.10 | ±0.20 |
| 30 – 120 | ±0.15 | ±0.30 |
| 120 – 400 | ±0.20 | ±0.50 |
| 400 – 1000 | ±0.30 | ±0.80 |
| 1000 – 2000 | ±0.50 | ±1.20 |
Values from ISO 2768-1 for linear dimensions. Angular and geometric tolerances follow the same class and are stated on the drawing.
| Class | Use it for | Avoid it for |
|---|---|---|
| 2768-m | Default on machined prototypes; covers most non-mating features. | Bearing seats, seals and anything that must interchange. |
| 2768-f | Fits and gaps on visible part lines; parts that assemble by hand. | Features that need a measured Cp/Cpk record. |
| ±0.02 mm | Named critical features, after review, with the method agreed. | Every dimension on the sheet — the cost is in the inspection. |
Reachable accuracy
- Standard±0.05 mm
- On request±0.02 mm
- As machined Ra0.8 – 3.2 µm
- Fine finish Ra0.4 µm on request
- Bead blast Ra1.6 – 3.2 µm
Inspection
Critical features are measured on a coordinate measuring machine and reported against the drawing. A first article inspection (FAI) sheet records every dimension on the first part of a run, and can be shipped with the order.
- CMM report with datum reference and measurement temperature.
- FAI sheet on request, aligned to the ballooned drawing.
- Third-party inspection (SGS, TÜV) quoted as a separate line.
Anodising builds 2–5 µm per surface. If a dimension is anodised after machining, say so on the drawing — the pre-finish size has to be adjusted.
Matched to the part before the quote is written
Travel, spindle and fixture decide which machine runs your part. The quote names the setup, so the tolerance you read is the tolerance the machine can hold.
| Equipment | Axes | Working envelope | Typical work |
|---|---|---|---|
| Vertical machining centre | 3 | 850 × 500 × 550 mm | Housings, plates, pockets, heat sinks |
| 4-axis VMC | 4 | 600 × 500 × 500 mm | Cross-holes, slots on four faces, cylindrical features |
| 5-axis VMC | 5 | 600 × 500 × 500 mm | Undercuts, steep walls, organic surfaces in one setup |
| CNC lathe + live tooling | 2 + C | Ø 320 × 600 mm | Shafts, bushings, threaded fittings |
| Surface grinder | — | 600 × 300 mm | Flatness and parallelism after hardening |
| CMM | — | 700 × 600 × 500 mm | Dimensional reports, GD&T verification |
Maximum part size: 850 × 500 × 550 mm is the largest confirmed envelope in the standard machine set. Selected partner factories can take 1200 × 600 × 500 mm — typical, confirm per part before you design around it.
Fixtures: thin walls, flexible plastics and second-operation features are quoted with a soft-jaw or dedicated fixture where needed. The fixture cost appears as a line item, not inside the unit price.