Article courtesy of NBK
WASHERS
Washers are available in a variety of types, sizes, and materials. Steel and stainless steel are the most common, but other metals and plastics are also used, depending on the application. Regardless of the washer chosen, installing with the proper torque is the best way to ensure a reliable hold.
How do flat and lock washers differ? Generally, washers are used to distribute a fastener’s load, reducing friction and preventing loosening. A washer is a plate with a hole, which lets a fastener pass through it. The most common shape is a flat disk with a concentric hole. Before a threaded fastener, such as a bolt, is driven into an application’s surface, a washer is often placed through the end for greater protection during installation and over time. This is because threaded fasteners stress the material in which they’re used. During installation, the washer works
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by absorbing the compression forces of the bolt as it’s driven into the application. A washer is positioned at the top of the bolt’s shaft where it meets the head and slides into the mounting hole, preventing the bolt head and nut from scratching or indenting the surfaces of the two fastened parts. Otherwise, without the washer, this could damage the application’s surface and eventually loosen the fastener. So, washers often offer greater reliability. There are several types of washers available and, as with any fastener,
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choosing the ideal one depends on the application. For example, they might be sprung to prevent vibration and loosening or to indicate the correct preload. They might be serrated or tabbed to prevent unscrewing. Regardless of which washer is chosen, tightening with the proper torque is the best way to ensure a reliable hold. By far, the most common is the flat (or plain) washer. Its purpose is to distribute a fastener’s load while reducing heat and friction during the installation process. DESIGN WORLD
