Every sheet metal part has tolerances, but making them too tight increases costs.
If there are no drawing tolerances, your parts will be fabricated with Tripar’s standard default tolerances to streamline production and avoid additional tooling. Please review tolerances and use them for your next projects too.
Standard default tolerances
The sketch above is for illustrative purposes only.
| DIM | Tolerance (“ ±) | Description |
|---|---|---|
| ±0.010” | Holes1 & linear dimensions of flat pieces < 0.5” | |
| ±0.015 | Holes1 & linear dimensions of flat pieces 0.5”< 4.0” | |
| ±0.020 | Holes1 & linear dimensions of flat pieces 4.0” < 12.0” | |
| Upon Review | Holes1 & linear dimensions of flat pieces > 12.0” | |
| A | ±0.010 | End to hole or bend |
| B | ±0.010 | Hole center-to-center (on one surface/plane) |
| C | ±0.015 | Bent edge to hole2 |
| D | ±0.020 | Distance over 2 bends2 |
| E | Undefined (TBD) | Distance over 3 or more bends2 |
| F | ± 2° | Angles3 |
| R | 1-2X Material thickness | Inside bend radii |
1 If the hole is not round, the above ranges apply to the largest dimension in the opening.
2 As measured nearest to bend(s).
3 Thin metals have some flexibility, and thus can deflect, even under their own weight. As such, tolerance applies up to 1” from the bend. For reference; 2° over 1” = .034”.
Metal finish
Surface finish: In accordance to material specified and associated governing specifications.
Formed or bent parts may have small surface blemishes near the areas of transition.
Residue: Metal fabricated parts are often produced and may be shipped with lubricants or dry film lubricants.
Protective film: For raw materials which come with a protective film, parts shall be provided with this film, to help protect the parts until you, the customer remove when desired.
Metal burrs
Small metal burrs are a normal part of metal stamping and CNC fabrication processes. Being nearly impossible to quantify and measure, unless otherwise specified, they shall be provided in their “as stamped” or “as fabricated” condition. Additional costs for deburring can be arranged if required.
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For those providing their own tolerance drawings, consider the two TriparTech articles that discuss sound sheet metal design practices.