Metallplugg

Metallplugg is a Swedish term for a metal plug or metal insert used in mechanical assemblies to reinforce, join, or seal components. The concept covers several related devices that share the property of being made of metal and serving as an intermediate part in a connection or closure.

One of the most common forms is the threaded insert (metallinlägg), a metal sleeve or insert installed into a pre-drilled hole in wood, plastic, or softer metals to provide durable internal threads for bolts or screws. Threaded inserts can be knurled, press-fit, or adhesive-bonded, and they allow repeated assembly without damaging the base material. They are widely used in furniture, automotive, and electronic housings.

Other variants include expansion plugs used to anchor fasteners in concrete or masonry by expanding as a bolt is tightened, providing a secure hold in hard substrates. There are also metal plugs that function as end caps or seals, covering openings in pipes, tubes, or housings to protect against ingress or leakage.

Materials commonly used for metallplugg include steel, stainless steel, brass, and aluminum, with coatings or platings to enhance corrosion resistance or reduce wear. Selection depends on load requirements, environmental exposure, and compatibility with the host material.

In practice, metallplugg serve to extend thread life, enable modular assembly, improve sealing and anchorage, or provide protective closures. The term emphasizes the metal nature of the insert or plug and its role as an intermediate component in a larger system.