Thread inserts lock in on plastics

Cross Manufacturing reports an interesting development in the application of locking wire thread inserts, following a lengthy programme of vibration testing on its Spiralock thread inserts. These tests demonstrated a locking performance that is equally good in steel, aluminium – and plastic, opening up the opportunity for using these inserts in many new applications involving the joining of plastics.

This ability to grip while resisting the effects of vibration and allowing dismantling and reassembly with no deterioration in performance, should prove attractive in many applications. One of the plastics tested, Sustarin C, is widely used for precision machined components in the food and pharmaceutical industries, whilst GRP (glass reinforced plastic), which was also tested, is the staple diet of the boat building industry. In addition, plastics are increasingly used in the manufacture of automotive panels, where the capability for swift assembly and replacement is a positive advantage.

Spiralock wire thread inserts feature a novel thread profile, which transmits the tightening loading down the full length of the bolt to achieve their locking performance and resistance to vibration. This is a departure from the distorted thread design of conventional prevailing torque alternatives. The Spiralock profile not only produces a free running performance when inserting the bolt but is also allows multiple re-use with no deterioration in locking performance. Testing programmes in metals have also confirmed resistance to vibration induced loosening.

In addition to Sustarin C and GRP, the inserts were tested in Nylon 6 and PET, a plastic typically used for bottles and packaging. In all cases an M6 x 3D insert was used with an ordinary bolt and the results were virtually identical for all these materials.

Contact Details and Archive...

• Cross Manufacturing 1938 Ltd

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