A shoulder washer can also be known as an insulation sleeve. The shoulder washer is designed to insulate screws, rivets or wire from an assembly. Features and Benefits of a shoulder washer Thermally insulate a screw from making metal to metal contact Reduce Vibration Act as Spacers and Guides Are Strong and Corrosion Resistant Can be Used as Seal in Some Applications Why and when to use a shoulder washer? Shoulder washers can be inserted into a housing to provide a bearing surface for rotary applications. The flange on the shoulder washer is used to locate the bushing when it is installed or to provide a thrust bearing surface. Shoulder Washers are used to prevent heat flow through the screw to other parts of the thermal assembly.