| Nominal Wall Thickness ($e_n$) (mm) | Tolerance (mm) | | :--- | :--- | | $3.0 < e_n \le 4.0$ | $\pm 0.5$ | | $4.0 < e_n \le 5.0$ | $\pm 0.6$ | | $5.0 < e_n \le 6.0$ | $\pm 0.7$ | | $6.0 < e_n \le 7.0$ | $\pm 0.8$ |
In the manufacturing of plastic parts, applying standard metal tolerances (like ISO 2768) is not practical. Plastics behave differently during and after cooling. iso 20457 tolerance table pdf
Ana read until the shop lights hummed awake, and her mind stitched the dry numbers to the machines she knew best: a precision lathe, a column drill, a tiny vertical mill she had affection for. She began to rework an old coupling that had been slipping on a generator shaft. With the tolerance table open beside her, she adjusted diameters and chamfers, selected fits that would reduce vibration, and calculated clearances that would let thermal expansion breathe without sacrificing engagement. The first coupling she finished felt right in a way that was more than fit—it was a small piece of order restored. | Nominal Wall Thickness ($e_n$) (mm) | Tolerance
ranging from TG1 to TG10. These groups are further divided into based on production effort: Series 1 (Standard Production): She began to rework an old coupling that
If your general tolerance block references "ISO 20457 – m", you do not need to write individual tolerances on every dimension. The machinist knows to adhere to the Medium tolerance table.