Custom DIN931 Hex Screws

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Product introduction: The DIN931 hex bolt is also called DIN9331 outer hex bolt and it conforms to the international standard ISO4014. Yijin Hardware is a factory dedicated to the manufacturing of DIN931 hex screws, and also a custom hex screw supplier. The DIN931 hex bolt is a fastener composed of a hex head and a rod with male threads and usually used together with a nut for fastened connection between two parts with through holes. The DIN931 hex bolts are half threaded, which means that the rod is partially threaded, and divided into class A and class B. The outer hex bolts must has the logo of its manufacturer and its property class, preferably in concave or convex form on the head top surface, or in concave form on the head side surface. The outer hex bolts of all property classes must be marked. For stainless steel outer hex bolts, the steel groups should be included. For example, a stainless steel outer hex bolt is marked with A2-70 or A4-70 in in convex form on its head top surface.


Materials and surface treatment of DIN931 hex bolts: Carbon steel and stainless steel are used for DIN931 hex bolts.

By property class, the carbon steel outer hex bolts are divided into 5.6, 8.8, 10.9 and 12.9.

The carbon steel hex bolt’s surfaces are treated by electroplating with plain blue white zinc, plain color zinc, hot zinc, environmental color zinc, environmental blue white zinc, and environmental Dacromet, as well as high salt fog for 72H, 96H, 120H, 300H, 360H, and 720H. By property class, the stainless steel outer hex bolts are divided into A2-50, A2-70, A4-50, A4-70, C3, and C4.

The following table shows the stainless steel groups and chemical compositions:

Regular dimensions of DIN931 hex bolts

Application scope of DIN931 hex bolts: The DIN931 outer hex bolt with coarse threads is often used together with a nut for a threaded connection between two parts, and this is a detachable connection.

The outer hex bolts with fine threads and coarse threads function the same, except that the former has better self-locking and thus is used for the positions subjected to large impacts and chocks or alternating loads or for adjustments of fine-tuning mechanisms.

When using an outer hex bolt, pay attention to looseness prevention, or normal operation will be affected and even an accident will occur.

The looseness prevention methods include looseness prevention via friction, mechanical looseness prevention, and other looseness prevention measures.

Featuring easy connection, simple mounting, convenient removing and high efficiency.

The outer hex bolts are widely used for production, installation and maintenance in various industries, such as mechanical equipment, electronic products, communication devices, furniture fitment, and construction.

As a world-leading custom hex bolt factory, Yijin Hardware has provided custom fastener machining services for over 200 customers and is called a trustworthy custom fastener expert!


*If you already have the drawings, feel free to email us directly for a quick quote: