Machine Design

Self-Clinching Nuts

These nuts are squeezed into round, punched or drilled holes in sheet metal between a parallel punch and flat anvil. The nut is flush or less on the back side. No special hole preparation or tooling shape is necessary.

The self-clinching nut must be harder than the parent sheet material so that when it is squeezed into the sheet, the nut forces the sheet to cold flow into the undercut, locking the fastener to the parent material. For most self-clinching steel nuts, the mounting material should be less than Rockwell B 80 in hardness.

Self-clinching nuts can be used in materials as thin as 0.03 in. and, with some small threads, as thin as 0.02 in. They are available as self-locking prevailing-torque types, floating types, floating self-locking nuts and flush-both-side types. The fasteners are made of heat-treated steel, stainless steel or aluminum. They can be used in metals that are unsuitable for welding. They should be installed after the parent metal is painted, plated or anodized. Self-clinching studs and standoffs are available as well.

Because self-clinching nuts fit into prepared drilled or punched holes, locating jigs and fixtures are not necessary. They can be installed with available automated installation equipment at great labor savings.

TAGS: Fasteners
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