Insert Materials, Finishes, and Colourings

WTI's huge range of wire inserts are manufactured in many different materials, platings, and colourings

WTI's standard wire thread inserts are manufactured from aircraft quality 304/A2 Stainless Steel wire. Alongside these, we also stock and supply inserts in a range of alternative materials and finishes, each of which have their own unique benefits. We can also apply colouring to inserts too, which is often requested by customers for identification purposes.



WTI's standard wire inserts are produced from A2/304 Stainless Steel

304/A2 Stainless Steel

Aircraft quality wire is cold worked in accordance with SAE AS7245* to produce inserts that:

  • Have a high degree of toughness and hardness
  • Have a tensile strength above 200,000 psi
  • Have a hardness of RC 43-50
  • Can withstand a temperature range from -160°C to +420°C without detriment to its properties
  • Will withstand surges of up to 500°C
  • Have excellent corrosion resistance.

*Equivalent/former specifications include 18/8 Austenitic, DTD 734A, BS EN 2947, and W.NR.1.4301.

WTI manufactures inserts in A4/316 Stainless Steel

316/A4 Stainless Steel

Inserts produced in accordance with UNS S31600 that:

  • Can withstand a temperature range from -160°C to +425°C
  • Have superior corrosion resistance when compared to 304/A2 Stainless Steel
  • Are particularly suited to marine and saltwater applications, where there is exposure to galvanic corrosion.



WTI's phosphor bronze wire inserts

Phosphor Bronze

Inserts produced from a non-ferrous Copper/Tin alloy (in accordance with BS 2783 PB 102 EH*) that:

  • Have a low co-efficient of friction
  • Have good elastic properties
  • Can withstand a temperature range from -200°C to +300°C
  • Are exceptionally resistant to corrosion fatigue
  • Are anti-galling
  • Are particularly useful in applications where non-magnetic inserts are required.

*Equivalent specifications include AMS 7247 and DIN 17677.

Wire inserts manufactured from Inconel X-750

Inconel X-750

Produced from precipitation hardened Nickel Chromium alloy in accordance with SAE AS7246*, Inconel X-750 inserts:

  • Are especially corrosion resistant
  • Have a good creep rupture strength at high temperatures, to approximately 700°C.

*Equivalent specifications include EN3108 and W.NR.2.4669.


Nimonic 90®t 

A commonly requested material is that of Nimonic 90®, with inserts being manufactured from precipitation hardened Nickel Chromium Cobalt alloy, in accordance with BS HR503*. These inserts:

*Equivalent specifications include UNS N07090 and W.NR.2.4632.

Please note, Nimonic 90 inserts are only available upon special request.

t Nimonic 90® is a registered trademark of Special Metals.


Finishes, Platings, and Coatings

WTI's wire inserts plated in cadmium

Cadmium Plate

Electrolitically deposited Cadmium*:

  • Provides a barrier between dissimilar metals, which reduces the effect of galvanic corrosion
  • Has a high lubricity and excellent corrosion resistance, which together prevent seizure and galling between threaded components
  • Is not affected by alkalis
  • Is able to withstand marine conditions
  • Is suitable for operation in temperatures ranging from -200°C to +235°C.

*In accordance with Def Stan 03-19 (formerly DTD904).

WTI's wire inserts plated in zinc

Zinc Plate

Electrolitically deposited Zinc* ensures inserts:

  • Are suitable for operation in temperatures ranging from -200°C to +250°C
  • Can be used as an alternative to Cadmium plated inserts.

*In accordance with Def Stan 03-20 (formerly DTD903)


WTI's silver coated wire inserts

Silver Plate

Electrolitically deposited Silver*:

  • Prevents seizure and galling between threaded components at elevated temperatures
  • Is suitable for operation in a temperature range of -200°C to +650°C
  • Is widely used in aero-engine applications.

*In accordance with BS EN 2786 (formerly DTD939; its equivalent specification is QQ-S.365).


WTI's wire inserts coated in dry film lubricant

Dry Film Lubricant

A molybdenum di-sulphide dry film lubricant coating*:

  • Prevents seizing and galling between threaded components
  • Is particularly effective when used with screw locking inserts
  • Is suitable for operation in temperatures ranging from -100°C to +250°C.

*In accordance with MIL-L-46010.



A solid film heat cured PTFE dry film lubricant coating*:

IVD Aluminium

Ion vacuum deposited pure Aluminium coating*:

*In accordance with Def Stan 03-28 (equivalent specification MIL-DLT 83488).



At the customer's request, we are also able to provide wire inserts coloured red, green, and blue. The dye does not affect the inserts' performance and is merely an aesthetic choice, typically used as a means of easily identifying between free running and screw locking inserts.

WTI can dye inserts green, red, and blue