HELI INSERT FASTENERS Screw Thread Inserts are made of helically coiled 18-8 & 304 stainless steel & Inconel x-750 wire with a precise diamond shaped cross section to accommodate internal and external threads simultaneously. When assembled in a tapped hole the insert presents a permanent internal thread which conforms to standard specifications.

In addition to all the characteristics of Free Running inserts the HELI INSERT FASTENERS Screw-Lock insert has the unique feature of one or more of its intermediate coils are deformed polygonally. This serves to create strong resilient pressure onto the thread flanks of the bolt as it passes through. This in—built Prevailing Torque of the GRIP COIL positively locks screws & bolts safeguarding against loosening under vibration & impact.

Screws can be inserted by hand up to the grip coil, after which some mechanical means must be employed to overcome the locking medium.

HELI INSERT FASTENERS Screw-Lock inserts are coloured RED for identification only, to distinguish them from Free Running inserts.

A C.O.S.H.H. sheet is available for the Dye upon request.

To obtain the best performance from HELI INSERT FASTENERS Screw-Lock inserts it is recommended that only good quality close limit fit, rolled thread, oil lubricated screws or bolts are used. On no account should sub standard or "Black" bolts (with heat treatment scale) be used with HELI INSERT FASTENERS Screw-Lock inserts.

When using Unplated, Heat Treated or Stainless Steel screws with HELI INSERT FASTENERS Screw-Lock inserts an Anti Seize Compound (such as Molibdenum Disulphide) should be applied (preferably to the screw) to minimise galling & maximise cycle life.


Under no circumstances should thread locking compounds be applied to the assembly. This will almost certainly cause the HELI INSERT FASTENERS to withdraw.

The assembled HELI INSERT FASTENERS offers:

  • 1. High Tensile Stainless Steel Threads.
  • 2. Flank Hardness of 43-50 R.C
  • 3. Surface Finish of 2 to 4 Microns.
  • 4. Dimensional accuracy to Extreme Limits.
  • 5. Reduced Friction between Bolt & Female thread flanks.
  • 6. Greater Loading for an applied torque.
  • 7. Minimal Torsional Strain in the Belt.
  • 8. Even Distribution of load over ALL Threads.
  • 9. Greater Loading capacity.
  • 10. Maintains Pre-Load stretch in Bolt.