Quality Guide
Our Standard for General Tolerances: Unless a customer print is provided, all parts are manufactured and inspected to ISO 2768-mK tolerances. If a print is provided, the tolerances and requirements on the print will be followed.
Quality Management & Inspection
Every part is inspected before shipment. Our quality management system includes:
- First article and in-process inspections
- Final inspection to drawing and PO requirements
- Digital and hardcopy inspection reports available
- Material and process certifications on request
- Traceability and documentation for critical parts
For special requirements, please specify on your quote request or drawing. We can accommodate custom inspection plans, PPAP, and customer-specific documentation as needed.
What is ISO 2768-mK?
ISO 2768 is an international standard for general tolerances in machining and fabrication. The “m” (medium) and “K” (coarse) classes define permissible deviations for linear, angular, and geometrical dimensions, unless otherwise specified on the drawing. This standard is widely used for general engineering work.
- m (medium): Standard for most machined parts, balancing precision and manufacturability (linear/angle tolerances).
- K (coarse): Used for general geometrical tolerances (form and position).
Standard Linear Tolerances (ISO 2768-m)
| Dimension Range (mm) | Permissible Deviation (m) | Permissible Deviation (K) |
|---|---|---|
| up to 3 | ±0.1 mm | ±0.2 mm |
| over 3 to 6 | ±0.1 mm | ±0.3 mm |
| over 6 to 30 | ±0.2 mm | ±0.5 mm |
| over 30 to 120 | ±0.3 mm | ±0.8 mm |
| over 120 to 400 | ±0.5 mm | ±1.2 mm |
| over 400 to 1000 | ±0.8 mm | ±2 mm |
| over 1000 to 2000 | ±1.2 mm | ±3 mm |
For full details, see ISO 2768 or our Drawing Standards Guide.
Standard Angular Tolerances (ISO 2768-m)
| Dimension Range (mm) | Permissible Deviation (m) | Permissible Deviation (K) |
|---|---|---|
| up to 10 | ±1° | ±1° |
| over 10 to 50 | ±0°30' | ±1° |
| over 50 to 120 | ±0°20' | ±0°30' |
| over 120 to 400 | ±0°10' | ±0°20' |
For full details, see ISO 2768.
Key Geometrical Tolerances (ISO 2768-2, K Class)
ISO 2768-2 defines general tolerances for form and position. Here are typical permissible deviations for the K class (coarse):
| Tolerance Type | Feature Length (mm) | Permissible Deviation (K) | Description |
|---|---|---|---|
| Straightness / Flatness | up to 10 | 0.05 mm | Max deviation from a straight line or flat plane |
| over 10 to 30 | 0.1 mm | ||
| over 30 to 100 | 0.2 mm | ||
| over 100 to 300 | 0.3 mm | ||
| Parallelism | up to 100 | 0.3 mm | Max deviation between two parallel features |
| over 100 to 300 | 0.4 mm | ||
| Perpendicularity | up to 100 | 0.4 mm | Max deviation from 90° between two features |
| over 100 to 300 | 0.6 mm |
For more details or other tolerance types (e.g., symmetry, position), see ISO 2768-2 or our Drawing Standards Guide.
Typical Surface Finish (Reference)
ISO 2768 does not strictly define surface finish, but the following values are typical for general machined parts:
| Process | Typical Surface Finish (Ra, µm) | Notes |
|---|---|---|
| Milling/Turning (as-machined) | 1.6 – 3.2 µm | Standard for most CNC parts |
| Grinding | 0.4 – 0.8 µm | For critical surfaces |
| Bead Blasting | N/A | Matte, non-reflective finish |
| Polishing | 0.1 – 0.4 µm | Mirror or optical finish |
For specific finish requirements, please specify on your print or quote request.