M2.5 Hex Socket Countersunk Screw DIN 7991 Black Oxide Grade 10.9

Description

M2.5 hex socket countersunk screw has a 2.5mm diameter of external thread that commonly used in machine parts, die fixturing, and clamping. The flat socket head enables driving where there is not sufficient space for wrenches or sockets and allows the screw head to sit flush on the surface. Ever Hardware provides custom-made fasteners and customizable packaging.

The hex socket screw drive has a hexagonal recess and may be driven by a hex wrench, also known as an Allen wrench, Allen key, hex key or inbus as well as by a hex screwdriver (also known as a hex driver) or a bit. Tamper-resistant versions with a pin in the recess are available.

A countersink is a conical hole cut into a manufactured object, or the cutter used to cut such a hole. A common use is to allow the head of a countersunk bolt or screw, when placed in the hole, to sit flush with or below the surface of the surrounding material (by comparison, a counterbore makes a flat-bottomed hole that might be used with a socket-head capscrew). A countersink may also be used to remove the burr left from a drilling or tapping operation thereby improving the finish of the product and removing any hazardous sharp edges. The basic geometry of a countersink (cutter) inherently can be applied to the plunging applications described above (axial feed only) and also to other milling applications (sideways traversal).

10.9-grade steel M2.5 hex socket countersunk screw has 10X100 N/mm^2 tensile strength and 9 is a multiplier means 90% of 1,000 = 900 N/mm^2 is the yield strength of the grade.
Similarly, we also have grade 8.8, 12.9, 6.8 also. This is an imperial method implied by engineers to differentiate between different sets of steel grades. Mainly used to differentiate the bolts and nuts. Like Grade 10.9 Hexagonal Bolt.