DIN 7991 Hexagon Socket Countersunk Head Cap Screws

DIN 7991 Hexagon Socket Countersunk Head Cap Screws are metric fasteners with a countersunk head and internal hexagon drive. The countersunk head is intended to sit flush with a suitably prepared countersunk hole, while the hexagon socket allows tightening with an Allen key or hex bit. The product is commonly identified in the fastener market as a DIN 7991 socket screw or DIN 7991 countersunk socket screw.

DIN 7991 is a legacy German standard for this product type and has been replaced by the ISO 10642 series. The current international standard is ISO 10642:2026, which specifies hexagon socket countersunk head screws with reduced loadability due to their head design. Because DIN 7991 and newer ISO 10642 editions can differ in dimensional and mechanical requirements, buyers should specify the required standard and dimensional version when ordering.

These screws are commonly used where a flush or low-profile surface is required, including machinery, mechanical assemblies, equipment frames, fixtures, automation systems and general industrial construction. The countersunk head can reduce interference with adjacent components and create a cleaner finished surface when the mating hole is correctly countersunk.