Plain washers > Flat washers protect surfaces by evenly distributing torque when a bolt or screw is tightened. > They prevent corrosion between a steel screw and an aluminum surface. > Can also be used as spacers. > Flat washers are also called on to provide electrical insulation. Main Role of Flat Washers: > to increase the size of a screw's bearing surface area > reduce the surface pressure applied on the fastened object PURPOSE : To distribute the fastener's load while reducing heat and friction during the tightening process. They can also be used as spacers, as is common in industrial and domestic applications. Flat washers are also called on to provide electrical insulation.