The black flat head machine screws are also called black countersunk head screws. The screw has a uniform diameter the entire length of the shaft as opposed to tapered screws that have a pointed tip. They are used to fasten machine components, appliances, and more. 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 bit. Tamper-resistant versions with a pin in the recess are available. Ever Hardware provides custom-made black flat head machine screws and customizable packaging.
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). Therefore, countersinks overlap in form, function, and sometimes name with chamfering endmills (endmills with angled tips). Regardless of the name given to the cutter, the surface being generated may be a conical chamfer (plunging applications) or a beveled corner for the intersection of two planes (traversing applications).
12.9-grade steel means that a component manufactured from this grade of steel has 12X100 N/mm^2 tensile strength and 9 is a multiplier means 90% of 1200 = 1080 N/mm^2 is the yield strength of the grade.
Similarly, we also have grade 8.8, 10.9, 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 12.9 Hexagonal Bolt.
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| Category | Black Flat Head Machine Screws |
|---|---|
| Finish | Electro-Plating |
| Thread type | Metric/Imperial/According to Request |
| Material | Stainless Steel/Carbon Steel/Aluminum/Brass/Copper, etc. |
| Brand | Ever Hardware |
| Place of origin | China Mainland |
| Size | Customized as required |
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