Premier Precision Group's - Special Processing performs anodic treatment of aluminum and aluminum alloys per MIL-A-8625, Types I, II, and III (natural and dyed).   Anodizing is an electrolytic oxidation process used to develop an oxide layer on the surface of aluminum parts.  Anodizing increases corrosion resistance and wear resistance, and provides better adhesion for paint primers than bare metal.   Anodic films can also be used for a number of cosmetic effects, either with thick porous coatings that can absorb dyes or with thin transparent coatings that add interference effects to reflected light.   Anodizing is also used to prevent galling and improve lubricity of threaded components and mating surfaces.

Premier Precision Group's - Special Processing provides Chemical conversion coatings (chemfilm) in accordance with MIL-C-5541, MIL-DTL-5541F, (which describes "Chemical Conversion Coatings on Aluminum and Aluminum Alloys") and MIL-DTL-81706.   Chemfilm provides corrosion resistance and provides a surface for better adhesion of primers and paints than bare aluminum.   There are two classes of coatings to specify: Class 1A is a thick film and Class 3 is a thin film.   Chemical conversion coating forms a "gel-like" coating on the surface of aluminum alloys that flattens and hardens as it ages to provide a uniform protective layer.   Although the conversion layer forms a minimal coating build-up, it is still capable of withstanding limited exposure to corrosive environments.

Class 3 (there is no Class 2) coatings are intended for use as a corrosion preventative film for electrical and electronic applications where lower electrical resistance contacts, relative to Class 1A coatings and anodic coatings (MIL-A-8625 not discussed here) are required.   The primary difference between Class 1A and Class 3 is thickness.  Coating thickness is varied by immersion time, therefore the same chemical can be used for both classes.

Special Processing performs three types of passivation per AMS-QQ-P-35 (Types II, VI and VIII) for stainless steel alloy.

The passivation process removes "free iron" contamination left behind on the surface of stainless steel from machining and fabricating.   The residual contaminants are potential corrosion sites that result in premature corrosion and ultimately result in deterioration of the component if not removed.   In addition, the passivation process promotes the formation of a thin, transparent chrome-oxide film that protects the stainless steel from selective oxidation (corrosion).

Special Processing applies primers, paints, Teflon coatings, and dry film lubricants in accordance with aerospace and military industry standards.

Solid and dry film lubricants form a dry layer or coating that excludes moisture and reduces friction, binding, and wear.   They often contain additives such as corrosion, oxidation, and rust inhibitors.   Chemically active agents such as sulfur, phosphorous, or chlorinated compounds are added to the mixture to form a film to prevent seizure, sticking or surface adhesion under high pressure conditions.  

Coatings are applied per Aerospace, Military, and Commercial specifications.   Please see our Process Approvals page for detailed specification and certification information.

PTFE (polytetrafluoro ethylene) nonstick coatings are high lubricious coatings.   Typical coatings have high operating temperatures, extremely low coefficient of friction, good abrasion resistance, and good chemical resistance.

PTFE coatings can withstand a maximum use temperature of 600°F.  This coating is typically applied to a thickness of 1-3 mils.

Pressure flushing is an excellent way to clean passage-ways and blind ports to remove contamination, debris, and the grease and oil used to prevent rusting of components before use.

It is prudent to pressure flush a component after manufacturing and machining and immediately before fitting mating components during pre-assembly and assembly operations to prevent possible future problems.

Existing debris is often mobilized by manufacturing operations and may then accumulate in the passages and blind ports, causing, in extreme circumstances, failure of the system.

Castings are impregnated for a variety of reasons, the most common being to retain gases or fluids under pressure.  Examples of these would be air regulators, gas meters, pumps, gear housings, valves, fuel systems parts, refrigerant compressor housings, and aircraft housings.  These parts can hold pressure up to the burst strength of the casting.  Powder metal parts and plastic injection molded components are also impregnated for these reasons.

Powder metal parts and castings are also impregnated in preparation for other metal finishing operations, such as plating or painting.  Acids and other cleaning agents that are used in these operations may be absorbed into the pores and remain there during the rest of the operation.  Later, these fluids emerge from the pores, causing pits, blisters, or other blemishes on the surface.  Out gassing of air from the porosity during paint curing can also cause blistering.  Sealing the porosity prior to this eliminates this problem.

Impregnation is also occasionally done to prevent internal corrosion.  By sealing the pores, corrosive fluids cannot enter the porosity, which would later cause internal corrosion.