scope:

This part of ISO 6157 establishes limits for various types of surface discontinuities on bolts, screws and studs for general requirements.

It applies to bolts, screws and studs with

- nominal thread diameters 5 mm and larger;

- product grades A and B;

- property classes up to and including 10.9, unless otherwise specified in product standards or agreed between supplier and purchaser.

Limits for surface discontinuities on bolts, screws and studs for special requirements (e.g. automatic assembly) are laid down in ISO 6157-3. When the engineering requirements of the application necessitate that surface discontinuities on bolts, screws and studs be more closely controlled, it should be specified in the respective product standard, or the purchaser shall specify the applicable limits in the inquiry and purchase order.

Where the permissible limits for surface discontinuities indicated in clause 3 occur, the minimum values for the mechanical and functional properties specified in ISO 898-1 should still be met.

NOTES

1 The figures in clause 3 are examples only. They apply correspondingly also to other types of bolts, screws and studs.

2 The individual figures show the surface discontinuities exaggerated in some cases for clarity.