How to read this chart
Every row is a process we run ourselves, either on our Dongguan floor or through a vetted sister facility for the two die-casting lines. The numbers are production tolerances — what we guarantee on a shipped part, verified on CMM or coordinate measuring microscope — not theoretical machine resolution.
Standard tolerance is what you get if you write no callout on the drawing and specify ISO 2768-m in the title block. Tight tolerance is the best we hold on a single critical feature when you call it out explicitly. Asking for tight tolerance on every feature of a part is almost never economical — tolerance cost scales roughly with the square of the tolerance band narrowing.
Process tolerance capability — full table
| Process | Standard Tol | Tight Tol | Min feature | Ra | Max size | Lead |
|---|---|---|---|---|---|---|
| 3-axis CNC milling Best cost for boxy geometry. Undercuts require EDM or 5-axis. | ISO 2768-m (±0.1 mm) | ±0.01 mm | 0.4 mm wall, 0.2 mm feature | 0.4 – 3.2 μm | 2250 × 1850 × 800 mm | 3 – 5 days |
| 5-axis CNC milling Complex contours, aerospace, automotive. Priced ~1.4× 3-axis. | ISO 2768-f (±0.05 mm) | ±0.005 mm | 0.3 mm wall, 0.1 mm feature | 0.2 – 1.6 μm | 1000 × 800 × 600 mm | 5 – 7 days |
| CNC turning Cheapest for round parts. C-axis tapping / milling available. | IT8 (±0.03 mm on Ø50) | ±0.005 mm on Ø | Ø1 mm bar | 0.4 – 1.6 μm | Ø500 × L2500 mm | 3 – 4 days |
| Swiss turning Micro shafts, medical pins, connectors. Per-part cost lowest in volume. | ±0.02 mm | ±0.002 mm on Ø | Ø0.3 mm | 0.2 – 0.8 μm | Ø32 × L200 mm | 5 – 7 days |
| Sheet metal — laser + press brake Stamping, laser cutting, bending, welding — up to 20 mm steel. | ±0.1 mm flat, ±0.5° bend | ±0.05 mm flat, ±0.25° bend | Hole Ø ≥ material t, bend radius ≥ 1× t | Material finish + deburr | 3000 × 1500 mm flat | 5 – 7 days |
| Sheet metal — stamping (HSS) DP780 / DP1180 automotive high-strength steel — our specialty. | ±0.15 mm | ±0.05 mm | Hole Ø ≥ 0.8× t | Material + finish | Bed 2500 × 1500 mm | 2 – 4 weeks (tooling) |
| Vacuum casting (PU resin) Silicone mold from CNC master. Shore 30A – 80D resins, color-matched. | ±0.15 % of dimension | ±0.1 mm on critical | 0.8 mm wall, 0.5 mm detail | Mirror-of-master (VDI texture possible) | V2550 chamber, 600 × 600 × 500 mm | 7 – 10 days for 15 – 25 pcs |
| Rapid prototyping — SLA / DLP Appearance models, investment-casting patterns. UV-sensitive. | ±0.2 mm or ±0.2 % | ±0.1 mm small parts | 0.5 mm wall, 0.4 mm detail | Smooth (post-cure polish) | 800 × 800 × 550 mm | 1 – 3 days |
| Rapid prototyping — SLS (nylon) Functional prototypes, living hinges, interlocking assemblies. | ±0.3 mm or ±0.3 % | ±0.15 mm | 0.8 mm wall | Matte textured | 750 × 550 × 550 mm | 2 – 4 days |
| Rapid prototyping — MJF / SLM metal AlSi10Mg, 316L, Ti6Al4V. Usually hybrid with CNC for tight features. | ±0.2 mm or ±0.2 % | ±0.05 mm post-machined | 0.5 mm wall | 6 – 12 μm as printed | 400 × 400 × 400 mm | 7 – 10 days |
| Investment casting (steel / brass) Structural steel parts, 304/316/17-4PH. Minimum ~30 pcs. | CT6 (±0.5 mm on 100 mm) | ±0.1 mm machined features | 2 mm wall, 3° draft | 3.2 – 6.3 μm cast, finer when machined | 500 × 500 × 300 mm | 3 – 5 weeks (tooling) |
| Die casting (aluminum, zinc) Volume only — MOQ typically 2,000+. Refer to our low-volume page for <500. | NADCA Tol-T5 (±0.1 mm per 25 mm) | ±0.05 mm machined | 1.0 mm wall, 1° draft | 0.8 – 3.2 μm as cast | 900 × 500 mm shot | 6 – 10 weeks (tooling) |
Decision framework — which process holds your tolerance cheapest
If only one or two dimensions are tight and the rest can float at ISO 2768-m, you're almost always better off with 3-axis CNC, even for a 200-piece run. Paying the CNC cycle time is cheaper than building the tooling for a process that only becomes economical at higher volume.
If many dimensions are tight and the shape is turning-friendly (rotationally symmetric), CNC turning halves the machine time versus milling and usually wins on cost. If the tight features are on the outside diameter and the geometry is small, Swiss turning can hold ±0.002 mm on Ø at rates milling can't touch.
For runs above 500 pieces with no tight callouts, sheet metal (if flat-pattern designable) or investment casting become cheaper per piece — but tooling lead time pushes your first-article date out 3–5 weeks. A common pattern with our customers: we machine the first 20–50 pieces as a bridge run while the investment-casting tool is being made, so production never stalls.
What the chart doesn't show
Material matters as much as process. The tolerances above apply to well-behaved materials — aluminum 6061, stainless 304, POM, PEEK. Tool steels and titanium machine stiffer and hold tighter; they also cost more in cycle time. Glass-filled plastics vary with fiber orientation and will not hold Ra 0.4 μm without a non-standard polish. If your material is unusual, send us the drawing before committing to a tolerance callout.
Part size drives tolerance non-linearly. A ±0.01 mm tolerance on a 20 mm feature is easy; on a 2,000 mm feature, thermal expansion of the part itself during a 4-hour cycle means the fixture and ambient temperature start to matter. We quote long parts with reduced tolerance on length and tight tolerance only on the critical faces.
Concentricity and parallelism aren't on the chart. They're GD&T callouts and they stack on top of individual-feature tolerance. We hold concentricity of ±0.01 mm on turned features to Ø callouts, and parallelism of ±0.02 mm on machined faces. Ask if you need specific GD&T numbers.
Our verification — what you get shipped with the part
- FAI (First Article Inspection) report on every order, measuring every dimension on the drawing against its tolerance callout.
- CMM report on any dimension marked critical or flagged on the drawing, measured on Keyence or Mitutoyo CMM at 20 ± 2 °C in our metrology lab.
- Material certificate (EN 10204 3.1) for any steel or aluminum part on request.
- Surface finish sample on visible parts, so you can verify the Ra matches the drawing before production release.
Every shipment includes the inspection report and material cert as a signed PDF in the packing list. If your receiving QC needs a specific format — PPAP, IMDS, IATF dimensional layout, CPK on specific features — tell us at quote time and we'll align.