Hexagon fits bolts with long thread
1Key Takeaways
This standard specifies the properties of hexagon head fitted screws with a long threaded shank and nominal thread diameters d = 8 mm to 52 mm, in product classes A for nominal thread diameters d ≤ 10 mm and B for nominal thread diameters d ≥ 12 mm. For hexagon head fitted screws with nominal thread diameters d > 39 mm…
2Expert Interpretation
This in-depth analysis of the DIN 609:2016 standard for hexagonal long-threaded bolts covers dimensional tolerances, technical specifications, weight calculations, and a comparison of new and old keyway widths. It also includes detailed analysis of product categories, mechanical performance requirements, and selection recommendations for practical engineering applications, providing a professional reference for mechanical design and manufacturing.
DIN 609 Standard Overview and Revision Background
DIN 609:2016-12 is the technical standard for hexagonal long-threaded bolts published by the German Institute for Standardization. This standard was developed by Working Group AA of Committee NA 067-00-02 on Mechanical Connection Elements. Compared to the 1995 edition, this revision includes four major updates: updated normative references, editorial revisions, alignment of thread ends with the tapered end (CH) in accordance with DIN EN ISO 4753, and a change in the shank length dimension designation from y to ls.
Scope of Application and Product Classification
This standard applies to hexagonal bolts with a nominal thread diameter of d = 8 mm to 52 mm. Based on this diameter range, the standard is divided into two product grades: Grade A (d ≤ 10 mm) and Grade B (d ≥ 12 mm). For bolts with a diameter greater than 39 mm, the standard only specifies dimensional and tolerance requirements; other properties are subject to negotiation.
| Product grade | Thread diameter range | Applicable standards | Special requirements |
|---|---|---|---|
| Grade A | d≤10mm | DIN EN ISO 898-1 | All parameters applicable |
| Grade B | d≥12mm | DIN EN ISO 4759-1 | When d>39mm, some parameters need to be negotiated |
Detailed explanation of key dimensional parameters
The standard specifies the complete dimensional system of hexagonal fit bolts, including key parameters such as thread diameter, shank length, and keyway width. The mating diameter da adopts the k6 tolerance zone, which is usually used with holes in the H7 tolerance zone.
| Thread Specifications | Mating Diameter da(mm) | Keyway Width s(mm) | Head Height k(mm) |
|---|---|---|---|
| M8 | 9.001-9.010 | 13 | 5.15-5.45 |
| M10 | 11.001-11.012 | 16 | 6.22-6.58 |
| M12 | 13.001-13.012 | 18 | 7.21-7.79 |
Comparison of New and Old Keyway Widths
One of the important changes in the standard is the introduction of the new keyway width specified in DIN ISO 272, while retaining the old dimensions for spare parts requirements. The specific comparison is as follows:
| Thread specification | New keyway width (mm) | Old keyway width (mm) | Transition period treatment |
|---|---|---|---|
| M10 | 16 | 17 | Appendix A reserved |
| M12 | 18 | 19 | For spare parts only |
| M14 | 21 | 22 | Not recommended for new designs |
| M22 | 34 | 32 | For maintenance use |
Technical Delivery Conditions and Material Requirements
Technical delivery conditions are specified in accordance with DIN 267-2. Mechanical requirements are based on DIN EN ISO 898-1 (carbon and alloy steels) and DIN EN ISO 3506-1 (stainless steel). Surface treatment must comply with DIN EN ISO 4042 (electrogalvanizing) and DIN EN ISO 10683 (non-electrolytic zinc flake coating).
| Performance indicators | Carbon steel grade 8.8 | Stainless steel A2-70 | Test standard |
|---|---|---|---|
| Tensile strength | 800MPa | 700MPa | DIN EN ISO 898-1 |
| Yield strength | 640MPa | 450MPa | DIN EN ISO 898-1 |
| Elongation | 12% | 12% | DIN EN ISO 898-1 |
Standard Implementation and Engineering Application Recommendations
When selecting hexagonal fitting bolts in engineering design, focus on the following key points: First, determine the product grade based on the connection requirements. Grade A is suitable for general connections, and Grade B is suitable for important connections. Secondly, the fitting tolerance must be correctly selected. The standard fit is k6/H7, and other tolerance zones can be specified for special working conditions.
For maintenance applications, after the hole has been expanded, a fitting bolt with a 1mm larger shank diameter should be selected. For example, an M20 bolt should use a 22mm instead of a 21mm shank diameter, and the increased size should be clearly indicated in the labeling.
Bolts longer than 200mm should be graded at 10mm intervals. Try to avoid using odd-numbered threads and length specifications to reduce manufacturing costs and improve interchangeability.
Marking Specifications and Ordering Examples
The standard specifies a complete marking method: Taking an M16×60-8.8 bolt as an example, the complete marking is "Passschraube DIN 609-M16×60-8.8". For products with special requirements, such as an increased shank diameter or a special keyway width, the relevant parameters must be additionally noted in the marking.
Products with new keyway widths should include the "SW" code in the marking, such as M12×1.25×60-SW18-8.8. Products with old keyway widths are for spare part use only and are not recommended for use in new designs.