Clarification of Standards: DIN 931 vs. DIN 933

The product title references two distinct but related German Institute for Standardization (DIN) standards that define the bolt’s threading:

• DIN 933 (Fully Threaded): Bolts manufactured to this standard have a threaded shank along their entire length. This design is ideal for applications where the bolt is fully engaged in a tapped hole or when clamping force is distributed over the bolt’s full length.
• DIN 931 (Partially Threaded): Bolts manufactured to this standard feature a partially threaded shank with a smooth, unthreaded portion under the head. This design provides superior shear strength, as the unthreaded shank can bear higher sideways forces than a threaded section. It is preferred for applications requiring precise alignment and resistance to shear stress.

Clarification of Material Grades

The product page lists both carbon steel and stainless steel grades. It is crucial to understand the distinction, as the product is specifically described as Stainless Steel.

• Applicable Stainless Steel Grades:
  • A2 (e.g., A2-70): This is equivalent to Type 304 stainless steel. It offers excellent corrosion resistance for general-purpose use, making it suitable for construction, automotive, and machinery applications in non-marine environments.
  • A4 (e.g., A4-70, A4-80): This is equivalent to Type 316 stainless steel, which includes molybdenum. This gives it superior corrosion resistance, especially against chlorides and saltwater. It is the ideal choice for marine applications, food processing equipment, and chemical environments.
  • The numbers “-70” or “-80” indicate the tensile strength class. For example, “A2-70” has a minimum tensile strength of 700 MPa.
• Inapplicable Carbon Steel Grades:
  • The grades 4.8, 8.8, 10.9, and 12.9 are property classes for carbon steel bolts and are not applicable to stainless steel bolts. The inclusion of these in the product list is likely a generic placeholder for the company’s broader bolt offerings.

Product Parameters

Key Features

• Excellent Corrosion Resistance: Crafted from A2 (304) or A4 (316) stainless steel, these bolts are built to withstand rust and corrosion in demanding environments.
• High Tensile Strength: Available in various strength classes (e.g., 70, 80) to provide reliable and secure fastening for structural and load-bearing applications.
• Versatility: Offered in both fully threaded (DIN 933) and partially threaded (DIN 931) configurations to suit different clamping and shear requirements.
• Aesthetic and Functional Finish: The polished surface not only provides a clean, professional look but also reduces the risk of material adhesion.

Common Applications

• Marine Industry: Securing hull components, deck hardware, and engine mounts where saltwater resistance is essential (A4/316 grade recommended).
• Construction: Fastening structural elements, outdoor decking, and architectural features.
• Food Processing: Used in equipment where hygiene and resistance to corrosive cleaning agents are necessary.
• Automotive: Assembly and repair in areas exposed to the elements.
• Machinery & General Industry: Any application requiring a strong, reliable, and corrosion-resistant fastener.

Installation Guidelines

1. Ensure the hole is correctly sized for the bolt. A tapped hole is required if a nut is not used.
2. Insert the bolt through the components to be fastened.
3. If applicable, thread a compatible stainless steel nut onto the end of the bolt.
4. Use a correctly sized wrench (socket, open-end, or ring spanner) on the hexagonal head to tighten the bolt.
5. Tighten to the appropriate torque specification for your application. Caution: Over-tightening can damage the threads or the fastened components, while under-tightening can lead to a loose and unsafe connection.