Quality Guide
Our standard for general tolerances: Unless a print is provided, parts are manufactured to ISO 2768-mK from the CAD model. If you upload a PDF print, we follow the print.
The quoting tool does not have a tolerance dropdown. Upload a PDF with the STEP when you have a print, or put tight dimensions, GD&T, certs, or FAI in notes.
Quality Management & Inspection
We inspect parts before shipment using commercially reasonable shop practice unless the quote calls out a specific plan.
- Inspection to the print, model, and PO requirements
- Material certificates, inspection reports, and certificates of compliance on request
- First article, custom inspection plans, and PPAP when specified in quote notes
Extra documentation is not attached automatically in the portal. Ask in notes if you need a report or cert with the order.
What is ISO 2768-mK?
ISO 2768 is the usual title-block callout for dimensions that do not have an individual tolerance. mK means two classes together:
- m (medium): ISO 2768-1 linear and angular tolerances.
- K (medium): ISO 2768-2 geometrical tolerances (form and orientation). H is fine, K is medium, L is coarse.
Linear Tolerances (ISO 2768-1, class m)
| Nominal size (in) | Permissible deviation (m) |
|---|---|
| 0.02 to 0.12 | ±0.0039 in |
| over 0.12 to 0.24 | ±0.0039 in |
| over 0.24 to 1.18 | ±0.0079 in |
| over 1.18 to 4.72 | ±0.0118 in |
| over 4.72 to 15.75 | ±0.0197 in |
| over 15.75 to 39.37 | ±0.0315 in |
| over 39.37 to 78.74 | ±0.0472 in |
Dimensions below 0.5 mm need an individual tolerance. Values are ISO 2768-1:1989. For full details, see ISO 2768-1 or our Drawing Standards Guide.
Angular Tolerances (ISO 2768-1, class m)
Range is the length of the shorter side of the angle, not the angle itself. Class m matches class f for these values.
| Shorter side (in) | Permissible deviation (m) |
|---|---|
| up to 0.39 | ±1° |
| over 0.39 to 1.97 | ±0°30′ |
| over 1.97 to 4.72 | ±0°20′ |
| over 4.72 to 15.75 | ±0°10′ |
| over 15.75 | ±0°5′ |
Values are ISO 2768-1:1989. For full details, see ISO 2768-1.
Geometrical Tolerances (ISO 2768-2, class K)
Class K is the medium geometrical class. Parallelism is not a separate table: it is the greater of the size tolerance or the straightness/flatness value.
| Tolerance type | Feature length (in) | Permissible deviation (K) | Notes |
|---|---|---|---|
| Straightness / Flatness | up to 0.39 | 0.002 in | Max deviation from a straight line or flat plane |
| over 0.39 to 1.18 | 0.0039 in | ||
| over 1.18 to 3.94 | 0.0079 in | ||
| over 3.94 to 11.81 | 0.0157 in | ||
| over 11.81 to 39.37 | 0.0236 in | ||
| over 39.37 to 118.11 | 0.0315 in | ||
| Perpendicularity | up to 3.94 | 0.0157 in | Shorter side of the right angle |
| over 3.94 to 11.81 | 0.0236 in | ||
| over 11.81 to 39.37 | 0.0315 in | ||
| over 39.37 to 118.11 | 0.0394 in | ||
| Symmetry | up to 3.94 | 0.0236 in | Feature length |
| over 3.94 to 11.81 | 0.0236 in | ||
| over 11.81 to 39.37 | 0.0315 in | ||
| over 39.37 to 118.11 | 0.0394 in | ||
| Circular run-out | — | 0.0079 in | Applies regardless of diameter |
Values are ISO 2768-2:1989. Position and profile still need a callout on the print. See our Drawing Standards Guide.
Typical Surface Finish (Reference)
ISO 2768 does not define surface finish. These are typical values for general machined parts. As-machined is the default in the quoting tool.
| Process | Typical surface finish (Ra, µin) | Notes |
|---|---|---|
| Milling/Turning (as-machined) | 63 – 126 µin | Default in the quoting tool |
| Grinding | 16 – 31 µin | For critical surfaces — ask in notes |
| Bead Blasting | N/A | Matte, non-reflective finish |
| Polishing | 4 – 16 µin | Mirror finish — Other (see notes) on the quote |
For a specific Ra, put it on the print or in quote notes.