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What are press-in inserts?

What are press-in inserts?

Shop for Threaded Inserts
press-in insert Some inserts for plastic and wood can be pressed into a hole using an arbour press or hammer. These inserts are not externally threaded, but they do have other features which secure them in the hole.The external fastenings on a press-in insert are called knurls; they stick out of the insert and embed themselves into the application material.
thermoset plastic items There are specific types of plastic and wood in which press-in inserts can be used; one of which is thermoset plastic. This means the plastic is permanently set to a certain shape and cannot be reheated, which is why press-in inserts are beneficial.
softwood with inserts Press-in inserts can also be used in some softwoods. Softwoods are generally, but not necessarily, softer than hardwoods. The classification is more to do with the way the trees seed.

How to install a press-in insert

drilling a hole in plastic and wood

Step 1 – Pre-drill hole

Pre-drill an appropriately sized hole for the insert. This should be just smaller in diameter than the insert, there should be a guide as to which drill bit to use with the inserts you purchase.

Press-in insert using arbour press or hammer

Step 2 – Push insert down

Hold the insert above the hole and push down using either an arbour press or light taps from a hammer.

fixed threaded insert in wood with knurls As the insert is forced down, the knurls push into the application material and prevent the insert from pulling out.

press-in insert expands with screw


Some varieties of press-in insert will include lengthways slots which cause the insert to slightly curve inwards when installed. This feature means that when the male threaded item is screwed in, the insert expands and takes even better to the application material.

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