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CoilThread® Insert Plating and Coatings on Tangless® and Tanged Inserts - Article 0104

This issue of KATO Fastening News will discuss the different types of platings and coatings that are typically supplied on KATO CoilThread Inserts. On Tanged Inserts, the specifications for free-running inserts, NASM122076 series and NASM124651 series do not have the provision to specify coated or plated inserts by the MS part number. However, NASM21209, the spec for locking Tanged Inserts and NAS1130, the spec for both free running and locking Tangless Inserts give you the option of specifying either cadmium plating or dry film lubricant coating in the part number. In any case, either of these optional coatings plus some additional ones can always be specified in the Kato part number for any of the insert types.

Cadmium Plating: Material specification: QQ-P-416 Type II. Provides a high degree of corrosion resistance. Used in harsh environments and is commonly used in aerospace applications, although it is not suitable for space applications due to its out-gassing properties. Used frequently in marine applications due to its excellent corrosion resistance in salt water environments. Provides lubricity to prevent or minimize galling when using locking inserts. Temperature capability up to 450° F. Chromate finish for identification, free running inserts: iridescent yellow; locking inserts: olive drab. Cadmium plating is designated by a “P” suffix in the MS21209 or NAS1130 part numbers, and by a “Y” suffix in Kato part numbers.

Dry Film Lubricant: Material specification: AS5272. Provides lubricity to prevent or minimize galling when using locking inserts. Provides some corrosion resistance. Temperature capability -365° to +500° F. Reduces insert installation torque and increases tooling life. Color: Dark Grey. Designated by an “L” suffix in the MS21209 part numbers, a “D” suffix in the NAS1130 part numbers, and by a “W” suffix in Kato part numbers. Can be used instead of a Xylan resin-bonded fluoropolymer coatings and still maintain the MS or NAS compliance (which is not possible with the Xylan coating).

Silver Plating: Material Specification: AMS2411. Silver’s anti-galling characteristics provide lubricity at high temperatures which is especially beneficial when using locking inserts. Temperature capability up to 1,200° F. Corrosion protection is considered to be only fair, and it tarnishes easily. Solderability, electrical conductivity, and thermal conductivity are excellent. Non-magnetic and expensive. Color: White silver. Not an available plating in MS and NAS1130 insert specifications. Add a “V” suffix to Kato part numbers for silver plating.

Other platings and coatings have been applied to inserts as requested by customers for their specific applications. Please contact the KATO Tech Group if you have any specific questions on alternate platings or coatings.

One of our competitors offers a resin-bonded fluoropolymer coating on inserts as a supposed replacement for using zinc chromate primer in tapped holes to prevent galvanic corrosion. We disagree and encourage you to read Xylan/Primer-free Plating, Resin-Bonded Fluoropolymer Coating on Inserts is Not a Replacement for Zinc Chromate Primer in Tapped Holes (Article 0102) before changing to this costly and questionable alternative.

Also, always remember that the plating thickness on an insert builds up eight times on the pitch diameter of the installed insert. For example; a plating thickness of .0001” on the insert will change the installed insert pitch diameter by 8 x .0001 = .0008”. You can learn more on the technical characteristics of platings in the September-October 2002 issue of Kato Fastening News.