THIS PAGE IS A BRIEF DESCRIPTION OF THE TYPES OF COATINGS THAT MACHFINISH CAN APPLY:
Aluminum Pigmented Coatings
The original specification for these coatings was MIL-L-85614, “Coating, Fastener (Titanium and CRES Alloys), Aluminum Pigmented, Organically bonded (For All Threaded and Unthreaded fasteners)”. This coating had specific performance requirements for installation force, corrosion protection, paint stripper resistance, fluid resistance, adhesion, and embrittlement of titanium alloy fasteners. It may still be used in some military applications, however, most of its requirements are carried forward in industry specifications. NAS 4006, “Aluminum Coating”, contains many of the same requirements as MIL-C-85614, except that installation force and embrittlement are not requirements. The original intended use of the coating was to provide a galvanic protective coating on threaded or non-threaded, interference fit or clearance fit fasteners. One important feature of MIL-C-85614 was that the cure temperature of the coating shall be not greater than 50°F below the minimum tempering temperature of the fastener and shall not be greater than 425F.
Solid Film Lubricants (Dry Film Lubricants)
Solid Film lubricants are materials that, despite being in the solid phase, can reduce friction between two mating surfaces without the need for liquid oil. They offer lubrication at higher temperatures than liquid oils can operate. Dry lubricants are often used in applications such as thread surfaces, bearing surfaces and dry lubricated bearings. These coatings are primarily produced to meet the requirements of AS5272 and MIL-PRF-46010. They are intended to provide lubricative and corrosion-protective properties for the surfaces to which they are applied. They are specifically tested for endurance life and load carrying capacity using the Falex Pin and Block wear tester in accordance with ASTM D2625.
There are three types of AS5272, as shown below.
Type I: A lubricant capable of being cured within 1 hour at 275°F-329°F (150 °C ± 15 °C), with a minimum endurance life of 250 minutes.
Type II: A lubricant capable of being cured within 1 hour at 375°F-427°F (204 °C ± 15 °C), with a minimum endurance life of 450 minutes.
Type III: A low volatile organic compound (VOC) content lubricant of being cured at 275°F-329°F (150 °C ± 15 °C within 2 hours, or within 1 hour at 375°F-427°F (204 °C ± 15 °C), with a minimum wear life of 450 minutes.
AS5272 Type I and II were created (technically equivalent) as industry replacements for military lubricants MIL-L-46010 Type I and II respectively, and noted in MIL-L-0046010E, dated 11 April 1997. AS5272, Type III was created by SAE as an alternative to MIL-PRF-46010F dated 10 August 2000 (originally designated MIL-L-46010, Type III). AS5272, Type III is technically equivalent to MIL-PRF-46010.
Epoxy Primers
Two (2) and three (3) part coatings are chemically activated and do not require heat or solvent evaporation to obtain a cured coating. In addition, these coatings contain a soluble chromate to meet corrosion resistance requirements.
MIL-PRF-23377 “Primer Coatings: Epoxy, High Solids”. This is a corrosion inhibiting, chemical and solvent resistant, solvent-borne, high-solids primer coatings that have a maximum volatile organic compound (VOC) content of 340 grams per liter (g/L) (2.8 pounds per gallon) as supplied by the manufactures.
Classification. The primer coatings are of the following types and classes.
Types:
Type I – Standard pigments
Type II – Low infrared reflective pigments
Classes:
Class C1 – Barium chromate-based corrosion inhibitors
Class C2 – Strontium chromate-based corrosion inhibitors
Class N – Non-chromate-based corrosion inhibitors.
MIL-PRF-85582 “Primer Coatings: Epoxy, Waterborne”. This is a corrosion inhibiting, chemical and solvent resistant, waterborne, epoxy primer coatings that have a maximum volatile organic compound (VOC) content of 340 grams per liter (g/L) (2.8 pounds per gallon) as supplied by the manufacturer. The classification and performance requirements of MIL-PRF-85582 are identical to MIL-PRF-23377.
BMS 10-11 “Chemical and Solvent Resistant Finish”
Classification. Primer coatings are of the following types, classes, and grades.
Types:
Type I – Primer
Type II – Epoxy Topcoat
Classes:
Class A – for spray application without electrostatic assist
Class B – for both spray and electrostatic assist spray application (No Class B primers have been qualified).
Grades:
Grade A – (primer or topcoat), 600 grams per liter OR MORE of VOC
Grade B – Solvent-borne Primer, 350 grams per liter OR LESS of VOC
Grade D – (High Solids Topcoat), 420 grams per liter OR LESS of VOC
Grade E – Water-Reducible Primer, 350 grams per liter OR LESS of VOC
Cetyl Alcohol (1-Hexadecanol) Solutions (AS87132)
These solutions are designed to be used as installation lubricants for mechanical fasteners such as pins, nuts, collars, washers, and bolts, and threaded or unthreaded fastening devices. They may be applied to clean bare metal surfaces, or to parts already coated with a paint film. On bare metal surfaces, these coatings help prevent galling or damage to threads (especially on titanium alloy parts) during assembly. On painted parts or solid film lubricated parts, additional re-usability is provided; as applicable, the use of Grade C solutions on these parts results in a lower force and more consistent installation of interference fit parts in aluminum structure as well as reducing the damage to the coating (which reduces the risk of galvanic contact between the fastener shank and the aluminum structure).
Classification:
The lubricant is classified in two types with grades as specified herein. Type I is the traditional classification and Type III is applied when environmentally necessary.
Type I – Petroleum Base Solvent
- Grade A: 30 to 90 grams of cetyl alcohol per liter (0.25 to 0.75 pound per gallon) of solvent.
- Grade B: 120 to 150 grams of cetyl alcohol per liter (1.00 to 1.25 pounds per gallon) of solvent.
- Grade C: 270 to 300 grams of cetyl alcohol per liter (2.25 to 2.60 pounds per gallon) of solvent.
Type III – Water Base Solvent
- Grade A: 10 to 30 grams (0.08 to 0.25 pound per gallon) cetyl alcohol per liter of deionized water.
- Grade B: 30 to 60 grams (0.25 to 0.50 pound per gallon) cetyl alcohol per liter of deionized water.
- Grade C: 60 to 100 grams (0.50 to 0.83 pound per gallon) cetyl alcohol per liter of deionized water.
Intended Use:
Cetyl alcohol, also called hexadecanol, is a white, crystalline, odorless, and noncorrosive and is compatible with fats, fatty acids, waxes, and petroleum oils. It is soluble in light petroleum base solvents and water. Cetyl alcohol is a nontoxic, non-irritating, and otherwise innocuous material; however, when dissolved in a petroleum base solvent, care should be taken in handling and storage because of the relatively low flash point of the dissolved mixture, attributed to the petroleum base solvent. It is intended for use as a lubricating coating to promote the installation of fasteners as follows:
- Grade A: Collars, nuts, and washers.
- Grade B: Pins, bolts, externally threaded parts, and noninterference fit fasteners.
- Grade C: Interference fit fasteners, internally threaded parts, and parts requiring heavy lubricant coating.