For helical thread inserts, DIN 8140 defines the dimensions, tolerances and product grades. The sections below describe the scope of the document, the properties it deliberately leaves to companion standards, and the equivalent designations across standards bodies.
DIN 8140 — Scope
DIN 8140 specifies the dimensions and tolerances of helical thread inserts. Material, property class, surface finish and packaging are governed by separate documents in the same standards family (for example ISO 898-1 for the mechanical property classes of bolts and screws).
Tolerance & Product Grades
DIN 8140, alongside the related DIN 8140 entries on this site, specifies product grades (typically A or B for fine work and C for general engineering) and tolerance classes for the controlling dimensions. Choose the grade against the precision your application requires.
Dimensions Specified by DIN 8140
| Thread size | Pitch (mm) | Length (mm) | Drill / tap size (mm) | Free coil diameter (mm) | Reference standard | Notes |
|---|---|---|---|---|---|---|
| M3 | 0.5 | 4.5 | 3.1 (STI tap) | 3.45 | DIN 8140 / ISO 10130 | Wire thread insert, 1.5xD length; tang break-off |
| M3 | 0.5 | 6.0 | 3.1 (STI tap) | 3.45 | DIN 8140 / ISO 10130 | Wire thread insert, 2xD length; tang break-off |
| M4 | 0.7 | 6.0 | 4.2 (STI tap) | 4.57 | DIN 8140 / ISO 10130 | Wire thread insert, 1.5xD length; tang break-off |
| M4 | 0.7 | 8.0 | 4.2 (STI tap) | 4.57 | DIN 8140 / ISO 10130 | Wire thread insert, 2xD length; tang break-off |
| M5 | 0.8 | 7.5 | 5.3 (STI tap) | 5.67 | DIN 8140 / ISO 10130 | Wire thread insert, 1.5xD length; tang break-off |
| M5 | 0.8 | 10.0 | 5.3 (STI tap) | 5.67 | DIN 8140 / ISO 10130 | Wire thread insert, 2xD length; tang break-off |
| M6 | 1.0 | 9.0 | 6.3 (STI tap) | 6.80 | DIN 8140 / ISO 10130 | Wire thread insert, 1.5xD length; tang break-off |
| M6 | 1.0 | 12.0 | 6.3 (STI tap) | 6.80 | DIN 8140 / ISO 10130 | Wire thread insert, 2xD length; tang break-off |
| M8 | 1.25 | 12.0 | 8.4 (STI tap) | 9.01 | DIN 8140 / ISO 10130 | Wire thread insert, 1.5xD length; tang break-off |
| M8 | 1.25 | 16.0 | 8.4 (STI tap) | 9.01 | DIN 8140 / ISO 10130 | Wire thread insert, 2xD length; tang break-off |
| M10 | 1.5 | 15.0 | 10.5 (STI tap) | 11.26 | DIN 8140 / ISO 10130 | Wire thread insert, 1.5xD length; tang break-off |
| M10 | 1.5 | 20.0 | 10.5 (STI tap) | 11.26 | DIN 8140 / ISO 10130 | Wire thread insert, 2xD length; tang break-off |
| M12 | 1.75 | 18.0 | 12.6 (STI tap) | 13.51 | DIN 8140 / ISO 10130 | Wire thread insert, 1.5xD length; tang break-off |
| M12 | 1.75 | 24.0 | 12.6 (STI tap) | 13.51 | DIN 8140 / ISO 10130 | Wire thread insert, 2xD length; tang break-off |
| M16 | 2.0 | 24.0 | 16.5 (STI tap) | 17.71 | DIN 8140 / ISO 10130 | Wire thread insert, 1.5xD length; tang break-off |
| M20 | 2.5 | 30.0 | 20.5 (STI tap) | 22.07 | DIN 8140 / ISO 10130 | Wire thread insert, 1.5xD length; tang break-off |
Equivalent Standards
Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent Helical Thread Inserts page. Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.
When to Specify DIN 8140
DIN 8140 is still widely used in European mechanical engineering and as a cross-reference on legacy drawings; its ISO equivalent is preferred for new designs.