Lock Washer Screw External Tooth Washer SEMS Screws Manufacturer

Lock washer screw combines two separate parts into one pre-assembled, low-cost fastener. With washers under the head, SEMS screw is fast, permanent, and easily adaptable to many applications. Ever Hardware provides custom-made fasteners and customizable packaging.

A washer with serrations that extend radially inward or outward to bite into the bearing surface. This type of washer is especially effective as a lock washer when used with a soft substrate, such as aluminum or plastic, and can resist rotation more than a plain washer on hard surfaces, as the tension between washer and the surface is applied over a much smaller area (the teeth). There are four types: internal, external, combination, and countersunk. The internal style has the serrations along the inner edge of the washer, which makes them more aesthetically pleasing. The external style has the serrations around the outer edge, which provides better holding power, because of the greater circumference. The combination style has serrations about both edges, for maximum holding power. The countersunk style is designed to be used with flat-head screws.

The Phillips screw drive was created by John P. Thompson, who after failing to interest manufacturers, sold his design to businessman Henry F. Phillips. Phillips is credited with forming a company (Phillips Screw Company), improving the design, and promoting the adoption of his product. The original patent expired in 1966, but the Phillips Screw Company continued to develop improved designs. Phillips drive bits are often designated by the letters “PH”, plus a size code 0000, 000, 00, 0, 1, 2, 3, or 4 (by order of increasing size); the numerical bit size codes do not necessarily correspond to nominal screw size numbers.

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