DIN 913 Dimensions

Technical Summary of DIN 913: Hexagon Socket Set Screws with Flat Point

1. Product Overview

• Standard: DIN 913 (December 1980), a modified national adoption of ISO 4026:1977.

• Product: Grade A hexagon socket set screws with a flat point.

• Application: For positional locking of components where a flat bearing surface against the mating part is required, minimizing surface marking.

• Scope: Covers metric screw threads from M1.4 up to and including M24. Sizes in parentheses (e.g., M1.8, M14, M22) should be avoided where possible.

2. Key Dimensions & Specifications

• Thread Sizes: M1.4, M1.6, (M1.8), M2, M2.5, M3, M4, M5, M6, M8, M10, M12, (M14), M16, (M18), M20, (M22), M24.

• Flat Point Diameter (d_p): Specified with max and min values for each thread size.

• Socket Size (s): Nominal hexagon key size (e.g., 1.5 for M3, 3 for M6, 10 for M20) with min/max tolerances.

• Socket Depth (t): Minimum depth specified. For very short screws, reduced socket depth applies and penetration of the hexagon bottom is not allowed; reduced tightening capability must be considered.

• Point Geometry: The tip is a cone with a 120° angle (mandatory for short screws). The transition from the thread root to the flat point diameter (d_p) is approximately 45°.

• Nominal Length (l): Ranges from 2 mm to 60 mm (depending on thread size), provided with min/max limits.

• Weights: Provided per 1000 pieces for reference (based on 7.85 kg/dm³ density).

3. Materials & Mechanical Properties

• Steel: Primary material.

  • Strength/Hardness Category: Standard category is 45H (as per DIN ISO 898 Part 5).

  • Other Categories: Other categories (e.g., 22H) can be supplied upon request and must be specified in the designation.

• Stainless Steel:

  • Grades: A2 (304 type), A4 (316 type), C3.

  • Strength Class: For A2, A2-70 for sizes ≤ M20, A2-50 for sizes > M20.

• Non-Ferrous Metal: Materials according to DIN 267 Part 18 (no specific alloy specified for set screws in this standard).

• Thread Tolerance:

  • Steel, category 45H: 5g6g

  • All other materials/categories: 6g

• Product Grade: A.

4. Technical Delivery Conditions & Finishes

• General Requirements: According to DIN 267 Part 1.

• Surface Finish:

  • Steel: Thermally or chemically blackened (black oxide).

  • Stainless Steel & Non-Ferrous: Bright (plain).

  • Electroplating or other coatings can be agreed upon at the time of order (ref. DIN 267 Part 9).

• Acceptance Inspection: According to DIN 267 Part 5.

5. Designation (Ordering Example)

• Standard Designation: Set screw DIN 913 – M6 × 12 – 45H

  • d = M6

  • l = 12 mm

  • 45H = Strength category

• For Product Grade F (Precision, sizes ≤ M2.5 only): Add "- F" (e.g., Set screw DIN 913 – M2 × 4 – 45H – F).

• Alternative ISO Designation (for international communication): Set screw ISO 4026 – M6 × 12 – 45H (Note: Only applies to non-shaded, pure ISO specifications in the standard).

6. Important Notes

• This DIN standard includes national amendments/additions to ISO 4026 (marked with shaded areas in the document), including additional sizes and the allowance for strength categories other than 45H.

• For sizes up to M2.5, a higher precision Product Grade F (per DIN 267 Part 6) is available for precision engineering applications.

• The flat point design is suitable for applications where minimal surface damage or a broader bearing area is desired compared to a cup point (DIN 916).