Cap Nut

A cap nut is an internally threaded nut with a closed domed end that covers the mating thread. It protects exposed thread ends and provides a finished surface on furniture, guards, railings and general hardware. Buyers should specify thread, cap height, style, material, finish, available thread engagement and stud projection. Safety and load values must come from the selected product standard, approval, drawing or test report; they cannot be inferred from appearance or nominal size. The RFQ should also state quantity, packaging, inspection and traceability requirements. This directory entry lists DIN 1587 as a catalog designation and a procurement reference. It is not proof that any product or supplier is certified or compliant. The listed materials are steel, stainless steel, and brass. Nominal size and range are supplier-specific; verify thread engagement and internal cap clearance. Strength and performance must match the mating fastener and avoid bottoming on the cap. Surface finishes include zinc-plated, nickel-plated, polished, or material finish. Always confirm model-specific values and standards with the legal manufacturer or supplier before use.

The internal thread develops clamp load while the closed cap encloses the projecting fastener end; bottoming must be avoided. When tightened, the nut's thread engages the bolt or stud, creating a clamping force. The domed cap covers the exposed thread end, protecting it from damage and providing a finished appearance. To function correctly, the cap must not contact the bottom of the threaded hole or the end of the fastener, as this would prevent proper seating and could reduce clamp load. Proper thread engagement and clearance are essential. The cap nut is typically used where a neat, safe end is required. The working principle relies on standard thread mechanics, with the cap serving as a protective cover. Always verify that the selected cap nut is suitable for the specific application, considering load requirements and environmental conditions.