Fasteners - Wing screws - Edged wings
1Key Takeaways
This standard specifies dimensions, designation and technical delivery conditions for wing screws, square wing shape, made of steel, malleable cast iron, austenitic steel and copper-zinc alloy with nominal sizes M4 to M12 in product class C.
2Expert Interpretation
This in-depth analysis of the German DIN 318 standard for angular thumbscrews covers dimensions, material selection, tolerance requirements, and key quality control points, providing professional fastener selection guidance for the machinery manufacturing industry.
DIN 318 Standard Overview and Revision Background
DIN 318:1999-07 is a specialized technical specification for angled thumbscrews developed by the German Institute for Standardization. This revised version replaces the previous version published in July 1999. The standard was developed by Working Group NA 067-00-08 AA, "Special Shapes and Plastic Fastening Elements," within the DIN Committee for Standardization of Mechanical Fastening Elements (FMV).
Scope of Application and Product Characteristics
This standard specifies the dimensions, marking, and technical delivery conditions for angled thumbscrews in nominal sizes M4 to M12, product grade C. Applicable materials include steel, malleable cast iron, austenitic steel, and copper-zinc alloy. The specifications for round thumb screws are separately specified in the DIN 316 standard.
| Material type | Code | Manufacturing process | Application characteristics |
|---|---|---|---|
| Steel | St | Forged or cold pressed | High strength general purpose |
| Mallable cast iron | GT | GTS or GTW process | Economical mass production |
| Austenitic Steel | A | Multiple Processes | Corrosion Resistant |
| Copper-Zinc Alloy | CuZn | Forged or Cast | Conductive and Magnetic Field-Proof Alloy |
Main Technical Parameters and Dimensional Requirements
The standard specifies in detail the key dimensional parameters of thumb screws, including wing root diameter (d3), wing width (e), wing thickness (g), wing height (h) and wing root height (m). The measurement methods and tolerance requirements of these parameters comply with the provisions of DIN EN ISO 225.
| Thread Specifications | Wing Width e(mm) | Wing Thickness g(mm) | Wing Height h(mm) | Wing Root Height m(mm) |
|---|---|---|---|---|
| M4 | 19.0-21.0 | 1.1-2.3 | 9-11 | 3.2-4.6 |
| M5 | 24.5-26.5 | 1.5-2.8 | 11-13 | 4.0-6. 0 |
| M6 | 29.0-32.0 | 1.5-3.3 | 14-16 | 5.0-7.0 | M8 | 35.0-38.0 | 2.0-4.4 | 17-19 | 6.5-8.5 |
| M10 | 47.0-50.0 | 3.6-5.4 | 22-24 | 8.0-10.0 |
| M12 | 63.0-6 6.0 | 4.1-6.4 | 29-32 | 10.0-13.0 |
Important Technical Changes
Compared to the 1999 edition of the standard, this revision incorporates several significant technical updates:
Tolerance Requirements Adjustment: The thread tolerance has been changed from 6g to 8g, reflecting advances in modern manufacturing processes and cost-effectiveness considerations.
Dimensional Accuracy Optimization: The number of decimal places in tables has been standardized, improving data readability and consistency.
Measurement Parameter Improvements: The maximum size limits for M8 and M12 have been revised, providing more flexible options for different applications.
Material Selection and Manufacturing Process
The standard allows thumbscrews to be manufactured using a combination of two materials, specifically malleable cast iron (GT) and steel (St). This design takes into account both manufacturing costs and ensures the mechanical properties of the product. The key requirement is that the connection design of the assembly must ensure that its mechanical and functional performance is no less than that of the integrally manufactured screws.
In actual applications, the choice of material should be determined by the use environment: austenitic steel is preferred for corrosive environments, copper-zinc alloys are selected when electrical conductivity is required, and steel or malleable cast iron are selected for general industrial applications.
Surface treatment and quality control
Surface roughness requirements follow the DIN 267-2 standard, while the requirements for electroplated surface protection are implemented in accordance with DIN EN ISO 4042. The standard specifically points out that the pressure-bearing surface remains unprocessed, which reduces manufacturing costs and ensures friction during installation.
Acceptance inspection is carried out in accordance with DIN EN ISO 3269 to ensure that each batch of products meets the specified quality requirements. Special surface treatment or coating requirements need to be negotiated separately between the supplier and the customer.
Implementation Recommendations and Application Guidelines
Selection Recommendations
When selecting a thumbscrew, factors such as the operating environment, load requirements, and installation frequency should be comprehensively considered. For applications with frequent manual adjustment, the angular wing design provides better torque transmission.
Installation Precautions
Avoid excessive torque during installation to prevent damage to the wings. For screws made of combined materials, attention should be paid to the differences in thermal expansion coefficients of different materials.
Key Points for Quality Control
Incoming inspection should focus on the wing dimensional tolerance, surface quality, and material certification. Regular sampling and torque testing should be conducted to ensure that product performance meets requirements.
Standard Evolution and Technological Development Trends
The successive revisions of the DIN 318 standard reflect the development of fastener manufacturing technology and changes in market demand. From the initial single material specification to the current permission for multiple material combinations, it reflects the practicality and foresight of the standard formulation.
Future development trends include more environmentally friendly surface treatment technologies, the use of higher-strength materials, and more precise manufacturing tolerance control. These developments will further promote the application and expansion of thumb screws in various industrial fields.
This standard, together with DIN 316 (circular thumb screws) and DIN 4000-160 (Characteristics table of external threaded connection elements), constitute a complete standard system for wing fasteners, providing a solid technical foundation for industry development.