Square head bolts with collar and short dog point with rounded end
1Key Takeaways
This standard specifies square head screws with a collar and shoulder, with a metric standard thread from M8 to M24 in product class A. Due to their small head bearing area, these screws cannot withstand full tensile loads. If, in special cases, specifications other than those in this standard are required, e.g., diffe…
2Expert Interpretation
This in-depth analysis of the DIN 480:2016 standard details the technical specifications for square-head bolts with flanges and short cylindrical ends. Covering dimensional tolerances, mechanical properties, material requirements, and implementation recommendations, it helps engineers select square-neck bolts that meet German standards.
DIN 480 Standard Overview and Revision Background
DIN 480:2016 is the latest technical standard developed by the German Institute for Standardization for square head bolts with flanges and short cylindrical ends, replacing the 1985 edition. This standard applies to Class A products with metric thread sizes M8 to M24 and is an important foundational standard for mechanical fasteners.
Major Technical Changes
Compared to the 1985 edition, the 2016 edition of DIN 480 has undergone significant technical updates: First, a comprehensive editorial revision has been made, including updated normative references; second, the thread end structure has been adjusted in accordance with DIN 962. Key changes include changing the a1 dimension of M8 bolts from 4mm to 3.75mm and adding a "0" prefix before the strength grade to clearly indicate that these bolts cannot achieve their full load-bearing capacity in tensile tests due to their small head bearing surface.
| Version comparison dimensions | DIN 480:1985 | DIN 480:2016 |
|---|---|---|
| Thread end standard | Old version specification | Complies with DIN 962-Ak |
| M8 Bolt A1 Dimension | 4mm | 3.75mm |
| Strength Grade Identification | Direct Marking | Add "0" Prefix |
| Reference Standard Update | Old Standard | Latest International Standard |
Product Structure and Dimension Specification
This standard specifies the detailed structural features of square neck bolts, including a square head, flange design, and short cylindrical end. Dimensional parameters cover nominal diameters d from M8 to M24 and lengths l from 16mm to 140mm, in 20mm increments. Key dimensions include head thickness k, flange diameter dc, and cylindrical end diameter dp. All dimensional tolerances are in accordance with the Class A requirements of DIN EN ISO 4759-1. The standard specifies three strength grades: 05.6, 05.8, and 08.8, corresponding to different material properties and mechanical characteristics. Due to the special structure of the square head, the load-bearing capacity of these bolts in tensile tests is limited, a technical point that requires special consideration when selecting them.
| Strength grade | Material requirements | Tensile strength | Yield strength |
|---|---|---|---|
| 05.6 | Carbon steel | 500 MPa | 300 MPa |
| 05.8 | Carbon steel | 800 MPa | 640 MPa |
| 08.8 | Alloy steel | 800 MPa | 640 MPa |
Surface treatment and corrosion protection requirements
Standard references DIN EN ISO DIN EN ISO 4042 sets detailed technical requirements for electroplated zinc coatings, DIN EN ISO 10683 for electroless zinc flake coatings, and DIN EN ISO 10684 for hot-dip galvanizing. Surface roughness complies with DIN 267-2, and the permissible range for surface defects is in accordance with DIN EN 26157-1.
Inspection and Acceptance Criteria
Acceptance inspection is performed in accordance with DIN EN ISO 3269 and includes dimensional inspection, mechanical testing, and surface quality assessment. Thread tolerances comply with the medium tolerance class requirements of DIN ISO 965-2 to ensure good interchangeability with mating nuts.
Implementation Recommendations and Application Guidelines
Selection Recommendations
When selecting square neck bolts, SW16 and SW21 wrench sizes should be prioritized. If other lengths or strength grades are required for special applications, these should be selected in accordance with the relevant standards and clearly indicated in the order.
Installation Precautions
Due to the special structure of the square head, sufficient space for wrench operation must be ensured during installation. The flange design provides a better bearing surface, but in high-load applications, the load-bearing capacity still needs to be verified to ensure it meets the requirements.
Quality Control Key Points
Manufacturers should focus on thread accuracy, head dimensional tolerances, and surface finish quality. During user acceptance, sampling inspections should be conducted according to the inspection methods specified in the standard. In particular, mechanical property tests should take into account the special characteristics of the head structure.
Standard Evolution and Technological Development
Since its initial publication in 1926, the DIN 480 standard has undergone several significant revisions. From the initial coarse thread to the current metric standard thread, and from simple dimensional specifications to a comprehensive performance index system, it reflects the continuous improvement of the German machinery manufacturing industry's technical requirements for connectors. The latest version of the standard places greater emphasis on coordination and unification with international standards, extensively citing ISO standards, and reflects the trend of global technological development.