Countersunk socket screws, DIN 7991
Screws
Countersunk socket screws to ISO 10642 / DIN 7991 join components through a conical head that sits flush with the surface of the counterbore. This category holds 387 versions, covering threads from M 5 to M 10, lengths from 16 to 70 mm and head diameters from 10 to 21 mm.
Selection follows thread size, shank length and material: stainless steel A2 or A4, or steel in property classes 8.8 and 10.9, zinc plated or plain. The across-flats size of the hexagon socket matches the thread size, ranging from 3 to 6 mm.
Screws of this type are used where the head must not stand proud of the component surface, for example on guides, covers, top plates and moving parts in machine building and jig making. The conical head centres the joint inside the countersink and carries transverse loads across the parting line. The hexagon socket allows tightening in tight spaces, because the key enters along the screw axis and no clearance is needed beside the head.
