Double Washers Screws Cross Round Head Flat And Spring Washer Attached

Double washers screws are also known as SEMS screws. SEMS 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.

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. 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.

Galvanization, or galvanisation, (or galvanizing as it is most commonly called in that industry), is the process of applying a protective zinc coating to steel or iron, to prevent double washers screws rusting. The most common method is hot-dip galvanizing, in which parts are submerged in a bath of molten zinc. Galvanizing protects in three ways:
It forms a coating of zinc which, when intact, prevents corrosive substances from reaching the underlying steel or iron.
The zinc serves as a sacrificial anode so that even if the coating is scratched, the exposed steel will still be protected by the remaining zinc.
The zinc protects its base metal by corroding before iron. For better results, the application of chromates over zinc is also seen as an industrial trend.

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