A primer on PowerCoil wire thread inserts – Part 3

In a recent articles we have been discussing some of the features of PowerCoil wire thread inserts. We will now talk about different materials and coatings that are available.

MATERIALS

PowerCoil standard inserts are manufactured from fully certified, aircraft quality, 304 (18/8) austenitic stainless steel in accordance with dtd 734A. Alternative materials include 316 stainless steel and a variety of application specific surface coatings.

ALTERNATIVE MATERIALS
Phosphor Bronze
Non ferrous copper/tin alloy in accordance with BS2783 PB 102 EH – is suitable for operation in temperatures ranging from -200°C to +300°C.

Inconel X-750
Heat resisting precipitation hardenable nickel base alloy (equivalent specifications SAE AS 7246, DIN/NF 3018, W.NR 2.4669, UNS N07750). Inconel X-750 is suitable for operation in temperatures ranging from -200°C to +550°C.

Nimonic 90
Heat resisting precipitation hardenable nickel base alloy in accordance with BS2 HR 501 (equivalent specifications W.NR 2.4632, UNS N07090).
Nimonic 90 is suitable for operation in temperatures ranging from -100°C to +650°C.

ALTERNATIVE FINISHES & COATINGS
Cadmium Plate
Electro-deposited cadmium in accordance with DTD 904/Def Stan 03-19 (equivalent specifications FED. QQ-P-416, LN 9368). Cadmium plating provides an excellent barrier between dissimilar metals dramatically reducing the effects of galvanic corrosion, its high lubricity and excellent corrosion resistance prevents seizure and galling between threaded components. Cadmium plate is suitable for operation in temperatures ranging from -200°C to +235°C.
Cadmium plated parts must not be
• subjected to temperatures exceeding 235°C (455°F)
• come into contact with fuel or hot oil
• come into contact with food or drinking water
• be used with titanium components (either directly or indirectly).
At elevated temperatures embrittlement and subsequent component failure may occur.
• cadmium is highly toxic – consequently extreme care must be taken when shipping, handling and installing.

Zinc Plate
Electrolytically deposited zinc in accordance with BS 3382. Electro-deposited zinc is the most widely applied electroplated finish in industry. Zinc is suitable for operation in temperatures ranging from -200°C to +250°C.

Silver Plate
Electrolytically deposited silver in accordance with DTD 939. Silver plating is used to prevent seizure and galling between thread components in high temperature applications and is most commonly applied to aero-engine fasteners. Silver plate is suitable for operation in temperatures ranging from -200°C to +650°C. Silver plated wire inserts may be installed in various materials including aluminium alloys, magnesium alloys, corrosion and heat resistant materials etc.
Silver plated inserts are not recommended for installation in titanium alloy which may exceed a service temperature of 300°C (570o°F). Stress corrosion as a result of the combination of silver and titanium may occur in the housing material.

Dry Film Lubricant
Solid film heat cured molybdenum disulphide dry film lubricant coating in accordance with MIL-L-0046010 provides a low frictional coefficient coating with excellent load bearing capabilities. Dry film lubricant prevents seizing and galling between threaded components and is particularly effective in screw locking insert applications. Dry film lubricant is suitable for operation in temperatures ranging from -100°C to +250°C.