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Using fasteners in tight installation situations, particularly in the field, can be a real headache but the new Combi-Washer from HEICO that uses the proven bolt security technology of the company’s HEICO-LOCK® Wedge Lock Washers, has an innovative design that takes away the pain.

When working with a bolted connection fiddling about with separate bolts, washers and nuts adds increased assembly time and cost during production as well as during regular maintenance. One answer has been to produce a SEMS screw that involves captivating a washer onto a screw or bolt in a one piece design but this is usually an expensive and time consuming process that requires specialist manufacture.

A traditional SEMS screw is created by placing the washer on the screw before it is thread rolled. Once thread rolled the diameter of the screw is larger than the washer hole and thus ‘captivating’ the washer in place, ensuring that it does not separate from the screw.

With the HEICO-LOCK® Combi-Washer the unique design combines an inner locking ring with inset tabs and the bolt securing qualities of the company’s HEICO-LOCK® Wedge Lock Washers. The inset tabs of the inner locking ring grip onto the bolt thread, creating a captivated washer. This means that once applied the washer will stay in place on the bolt even when the joint is disassembled for maintenance or repair. Not only does this greatly reduce the chance of dropped objects in the field but initial assembly during production is quicker and easier.

The HEICO-LOCK® Wedge Lock Washers use preload rather than friction to secure a bolted connection. The design has a combination of radial external teeth and internal wedge shaped cams. As the angle of the internal cams is greater than the pitch of the bolt thread any loosening causes movement in the region of the wedged cams. This creates an expansion in the thickness of the washers and as this thickness is greater than the possible longitudinal movement of the stud along the thread, increases the clamping force.

By integrating the inner locking ring with the bolt securing qualities of the HEICO-LOCK® system your bolt security is assured, at a fraction of the cost and time of producing a bespoke SEMS screw.

The Combi-Washer can be used in conjunction with all commercially available bolts which means you can create your very own SEMS part with your existing bolts. But HEICO don’t stop there as the company offer the service of supplying you with pre-assembled bolts so that you can use it as a SEMS part straight out of the box. Combining the Combi-Washer and bolt into one versatile fastener creates clear design and manufacturing benefits, not least bottom line savings for production. When using out in the field for onsite maintenance or repair the created SEMS screw is easier to remove and re-install than separate fasteners, particularly where space is tight or conditions demanding.

The Combi-Washer joins an already extensive range of bolt fastening systems from HEICO that includes the original HEICO-LOCK® Wedge Lock Washers, the Ring Lock system with its innovative outer polyamide ring; the Wedge Lock Nut which combines a hex nut with a captivated wedge lock washer and also the HEICO-TEC® tension nut which is ideal for use with larger bolt sizes up to M120. With easy assembly and permanent connection the HEICO-LOCK® Combi- Washer system offers a flexible, fast and innovative bolted joint solution, particularly for highly loaded bolted connections.

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