DIN 960 Hexagon Head Bolts | Fine Pitch, Partial Thread, Classes 8.8 & 10.9

Product Introduction
Metric hexagon head bolts manufactured to DIN 960 (withdrawn; superseded by ISO 8765). The bolt has a partial thread with an unthreaded shank beneath the head and a metric fine pitch thread. Sizes M8 to M24, including M8×1, M10×1.25, M12×1.25, M14×1.5, M16×1.5, M20×1.5, and M24×2. Fine pitch threads increase the minor diameter and thread engagement, improving vibration resistance and allowing more precise torque control than coarse threads. Typical applications include automotive engines, hydraulic systems, high-pressure fluid connections, and precision machinery.

Material & Mechanical Properties
Medium carbon steel or alloy steel, quenched and tempered to ISO 898-1.

• Class 8.8: minimum tensile strength 800 MPa; minimum yield strength 640 MPa; hardness 22–32 HRC.

• Class 10.9: minimum tensile strength 1040 MPa; minimum yield strength 940 MPa; hardness 32–39 HRC.
  For fasteners with nominal tensile strength ≥ 800 MPa, the standard friction coefficient is μ total = 0.12–0.18. Thread tolerance is 6g for plain finish and 6h for plated finish. Mechanical values are certified by lot with mill test reports available.

Geometry & Thread
Product grade A applies to threads up to M24 with lengths ≤ 10d or 150 mm, whichever is shorter; grade B applies to larger or longer bolts. Width across flats: M8 = 13.0 mm, M10 = 16.0 mm, M12 = 18.0 mm, M16 = 24.0 mm, M20 = 30.0 mm, M24 = 36.0 mm. Head height ranges from 5.3 mm (M8) to 15.0 mm (M24). Partial thread dimensions follow DIN 960; for example, M16×75 has a 38 mm thread length and a 37 mm unthreaded shank. ISO 8765 supersedes DIN 960 with revised widths across flats for M10, M12, M14, and M22. For coarse thread equivalents, ISO 4014 applies.

Surface Finish
Zinc plating with clear, blue, or yellow passivation; hot-dip galvanizing (HDG); black oxide; Dacromet; and Geomet. For HDG, threads are manufactured to tolerance class 6az (oversize) before coating per ISO 10684, ensuring final fit with standard 6H nuts. Class 10.9 bolts are subject to hydrogen embrittlement controls when galvanized or electroplated.

Marking & Certification
Each bolt head is permanently marked with the standard number (DIN 960 or ISO 8765), the property class (8.8 or 10.9), and the manufacturer’s identification mark. Full traceability is maintained from mill certificate to shipment. EN 10204 Type 3.1 inspection certificates are available on request. Go/No-Go thread gauging is performed on every batch.

Application Suitability
Automotive engine and drivetrain assemblies, hydraulic manifolds, high-pressure fluid connections, precision machinery, and vibration-loaded joints where fine adjustment and high clamp force are required. The partial unthreaded shank allows the shear plane to intersect the full-diameter section where joint design specifies it.