V-Coil 4 mm Wire Thread Repair Screw  Locking Inserts for M4 x 0.7 1.5 D 20 off

1.5D inserts installed length  6.0mm

Screw Locking Helical  Inserts

Screw locking (or prevailing  torque) inserts are of particular value in applications subject to the effects  of cyclic vibration or impact. In addition to the benefits afforded by free  running inserts, WTI screw locking inserts offer the additional security of  prevailing locking torque. This is achieved by the action of one or more polygonal  grip coils positioned within the inserts length, which excert radial pressure  on the male thread. Each grip coil consists of a number of tangential locking  chords which protrude inside the minor diameter of the normal free running coils.  As the male thread passes through these grip coils the locking flats are displaced  thus exerting radial pressure or prevailing locking torque on the male thread.  On removal of the male thread, the locking coils relax to their original form  permitting repeated assembly whilst retaining a measurable level of prevailing  torque. Note: it is recommended that only close fit plated or lubricated bolts  or screws are used with screw locking inserts.

Produced from precision profiled austenitic stainless steel wire wound into a helical spiral, free running inserts have a spring like appearance. When installed using any one of a variety of manual or automatic tools they provide strong permanent internal threads which resist heat and corrosion. Once fitted their position is maintained by the action of radial pressure between their coils and the flanks of the tapped hole.

This pressure exists because their free diameter is larger, by a calculated amount, than their installed diameter.

Inserts are 1.5D installed length this means 1.5 x diameter. Other installed length are available please email if this is your requirement and we can list on ebay for you.

Inserts are priced and supplied in packs of 20