SEMS Screws are machine screws that come with a pre-attached washer. Utilizing SEMS screws for your application can be a significant time-saver over buying separate screws and washers and manually assembling them.

SEMS Screws With External Tooth Lock Washers are the most commonly used style of SEMS screws. The angle of the external teeth allows them to dig into the bottom of the screw head and the material that it is going through. The teeth also extend slightly beyond the outer edge of the screws head, creating a wider bearing surface and adding greater torsional resistance to loosening.

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While providing slightly less strength, hold and torsional resistance, SEMS Screws With Internal Tooth Lock Washers offer different benefits. With the teeth pointing inward, under the screw head, they prevent snagging and provide a cleaner look with only the smooth, flat outer side of the washer exposed. 

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SEMS Screws featuring Split Lock Washers are the preferred type when used against hardened bearing surfaces. Rather than digging into the mating materials, the opposing ends of the split provide resistance to loosening by putting oppositional force against the bottom of the screw head and the bearing surface. Each end pushes against one or the other surface, providing the pressure needed to prevent the screw from slipping or loosening.

Fastener SuperStore also offers a wide selection of Double Washer SEMS Screws. Combining a split lock washer with a flat washer provides extra strength, a wide bearing surface and a clean smooth appearance.

Check out our full selection of SEMS Screws here!