INSTAVOXEL – MANUFACTURING STANDARDS
Last Updated: 02/08/2025
In CNC machining services, unless the drawings explicitly specify tolerances, we will follow “Standard Tolerances” for machining and quality inspection. The primary guidelines will be:
- For metal parts, the standard is ISO 2768-fH (fine)
- For plastic parts, the standard is ISO 2768-mK (medium)
The detailed content of the Standard Tolerances is as follows:
LINEAR DIMENSIONS
| Limits for nominal lengths
(Values in millimeters) |
Metals (ISO 2768-f) | Plastics (ISO 2768-m) |
| 0.5 up to 3 | ±0.05 | ±0.1 |
| over 3 up to 6 | ±0.05 | ±0.1 |
| over 6 up to 30 | ±0.1 | ±0.2 |
| over 30 up to 120 | ±0.15 | ±0.3 |
| over 120 up to 400 | ±0.2 | ±0.5 |
| over 400 up to 1000 | ±0.3 | ±0.8 |
| over 1000 up to 2000 | ±0.5 | ±1.2 |
| over 2000 up to 4000 | – | ±2.0 |
ANGULAR DIMENSIONS
| Limits for nominal lengths
(Values in millimeters) |
Metals (ISO 2768-f) | Plastics (ISO 2768-m) |
| up to 10 | ±1° | ±1° |
| over 10 up to 50 | ±0°30′ | ±0°30′ |
| over 50 up to 120 | ±0°20′ | ±0°20′ |
| over 120 up to 400 | ±0°10′ | ±0°10′ |
| over 400 | ±0°5′ | ±0°5′ |
EXTERNAL RADIUS AND CHAMFER HEIGHTS
| Limits for nominal lengths
(Values in millimeters) |
Metals (ISO 2768-f) | Plastics (ISO 2768-m) |
| 0.5 up to 3 | ±0.2 | ±0.2 |
| over 3 up to 6 | ±0.5 | ±0.5 |
| over 6 | ±1.0 | ±1.0 |
STRAIGHTNESS AND FLATNESS
| Limits for nominal lengths
(Values in millimeters) |
Metals (H) | Plastics (K) |
| up to 10 | 0.02 | 0.05 |
| over 10 up to 30 | 0.05 | 0.1 |
| over 30 up to 100 | 0.1 | 0.2 |
| over 100 up to 300 | 0.2 | 0.4 |
| over 300 up to 1000 | 0.3 | 0.6 |
| over 1000 up to 3000 | 0.4 | 0.8 |
PERPENDICULARITY
| Limits for nominal lengths
(Values in millimeters) |
Metals (H) | Plastics (K) |
| up to 100 | 0.2 | 0.4 |
| over 100 up to 300 | 0.3 | 0.6 |
| over 300 up to 1000 | 0.4 | 0.8 |
| over 1000 up to 3000 | 0.5 | 0.8 |
SYMMETRY
| Limits for nominal lengths
(Values in millimeters) |
Metals (H) | Plastics (K) |
| up to 100 | 0.5 | 0.6 |
| over 100 up to 300 | 0.5 | 0.6 |
| over 300 up to 1000 | 0.5 | 0.8 |
| over 1000 up to 3000 | 0.5 | 1 |
RUN-OUT
| Metals (H) | Plastics (K) | |
| Run-out tolerance | 0.1 | 0.2 |
THREADS
If the thread tolerance is not indicated on the drawing, metric thread tolerances shall follow to the ISO 965-1 (Medium) standard (6H for internal threads and 6g for external threads) and UN thread tolerances shall follow to the ASME B1.1 -2003 (Class 2A and 2B) standard (2B for internal threads and 2A for external threads).
| Internal Threads | External Threads | |
| Metric Threads | 6H | 6g |
| UN Threads | 2B | 2A |
SURFACE ROUGHNESS
Our standard specifies a surface roughness of Ra 125 microinches / 3.2 micrometers (N8).
