wolkerstorfer metal finishing

Glossary Terms

24-hour Immersion testing

This test involves a one hour immersion of a sample in distilled water, at room temperature, followed by a one hour drying cycle. This is then repeated for 12 cycles. If there is any evidence of staining or rust on the part the lot would be rejected.

440C Stainless Steel

This particular grade of stainless steel is susceptible to intergranular attack by nitric acid. In some of the older specifications it was recommended that this particular alloy not be processed through passivation.

Alodine™

A trade name for a bath concentrate used in the make-up of chromate conversion solution.

AMS 2700

One of the more popular specifications for passivation

AMS QQ-P-35

This has been canceled and is superseded by AMS 2700

Anodize

A coating, typically formed on aluminum, that provides an anodic aluminum oxide surface. This coating is non-conductive, provides corrosion protection and is also a reliable pretreatment for paint. Three of the most common types of anodize are Sulfuric, Boric-Sulfuric and Chromic Acid Anodize.

Anodize Seals

Typical seals include hot water, nickel acetate and dilute chromic acid. Their purpose is to seal the anodize coating providing improved corrosion protection.

Boric Sulfuric Acid Anodize

(BSAA) Meets MIL-A-8625, Type IC and BAC 5632. This Boeing patented and licensed anodize coating is a non-hexavalent chrome alternative to Chromic Acid Anodize. This is a RoHS compliant coating.

CARC

Chemical Agent Resistant Coatings were developed to protect military vehicles from chemical agents. This paint system is engineered to be easily decontaminated after exposure to chemical and biological warfare agents, and also protects against radioactivity.

Chemical Conversion Coating

(Chem Film) Meets MIL-DTL-5541, Type I (hexavalent) and II (trivalent). This is a protective chromic conversion film over aluminum that is conductive, enhances corrosion protection and is a good pretreatment for paint.

Chromic Acid Anodize

(CAA) Meets MIL-A-8625, Type I and Type IB. This coating is in the process of being phased out but is still active in some aerospace and defense applications. The coating contains hexavalent chrome meaning it is NOT RoHS compliant.

Citric Acid Passivation

Meets AMS 2700, ASTM A967, QQ-P-35, AMS QQ-P-35. This is one form of passivating stainless steel. There are various bath concentrations and temperatures that can be used, typically determined by the alloy of the stainless steel.

Coating Weight Testing

Certain coatings are qualified by physically weighing deposit as opposed to measuring the thickness. Type I and II anodize and phosphate coatings fall in this category. Although there is some actual buildup of these coatings the industry uses the weight as the acceptance criteria for validating these coatings.

Copper Sulfate Testing

This test is referenced in ASTM A967 as a way of detecting free iron on the surface of certain grades of stainless steel. The presence of copper on the surface of the part post-test indicates the presence of free iron, and is cause for rejection.

Copper Sulfate Testing

This test is referenced in ASTM A967 as a way of detecting free iron on the surface of certain grades of stainless steel. The presence of copper on the surface of the part post-test indicates the presence of free iron, and is cause for rejection.

Dry Film Lubricants

Dry Film Lubricants (DFL), also known as Solid Film Lubricants (SFL), provide lubrication in areas where wet lubricants are not practical. Dry Films are typically made up of formulas containing molybdenum disulfide, graphite, or Teflon™. Some Dry Films also provide excellent corrosion protection.

ELV

End-of Life Vehicles (ELV) is a European initiated program promoting the re-use or recycling of automotive parts, ultimately reducing the impact to landfills.

Fluorescent Penetrant Inspection

Also called Liquid Penetrant Inspection or FPI. This test system involves the use of penetrating solutions and subsequent developers to expose surface imperfections to the naked eye under ultra-violet light.

Friable Coating

A friable coating is designed to fracture on impact or in a “load on load” basis. Phosphates’ friable structure provide a sacrificial coating that facilitate in the initial break-in of assemblies that have metal to metal contact.

Hexavalent Chem Film

Meets MIL-DTL-5541, Type I. This conductive conversion coating contains hexavalent chrome which is being phased out due to environmental and health reasons. This is a NON-compliant RoHS coating.

Iridite™

A trade name for a bath concentrate used in the make-up of chromate conversion solution.

Liquid Penetrant Inspection

See Fluorescent Penetrant Inspection

Manganese Phosphate

Meets MIL-DTL-16232, Type M. It is used as a break-in lubricant or as a pretreatment for other coatings like paint.

MIL-DTL-5541

The most popular of the specifications for Chemical Conversion Coatings for aluminum. There are two “Types” and two “Classes” that can be designated. Type I has hexavalent chrome in it and Type II has trivalent chrome. The Class 1A is designed for maximum corrosion protection while the Class 3 is called out in applications where […]

MIL-PRF-46010

Coatings meeting this specification will provide excellent lubricity and corrosion protection. This is one of the more common heat cured Dry Film Lubricant specifications that is used in the field.

MIL-STD-1907

This specification provides the needed criteria for what visual imperfections are acceptable or not during the inspection process.

MIL-STD-1907 || MILSTD1907 || MIL STD 1907

This specification provides the needed criteria for what visual imperfections are acceptable or not during the inspection process.

Nadcap

Nadcap is the National Aerospace and Defense Contractors Accreditation Program. Nadcap is a global cooperative accreditation program for aerospace engineering, defense, and related industries. This quality initiative is designed to provide superior performance and standardization across all platforms.

Nitric Acid Passivation

Meets AMS 2700, ASTM A967, QQ-P-35, AMS QQ-P-35. This is one form of passivating stainless steel. There are various bath concentrations and temperatures that can be used, typically determined by the alloy of the stainless steel.

NonDestructive Testing

There are two types of testing for materials: Destructive which involves actually destroying a part in order to test its physical characteristics and NonDestructive which allows a person to test a component in such a way as to allow it to still be used in the field.

Paint

Paint is any pigmented liquid that after application to most substrates turns to a thin solid film. It is most commonly used to provide corrosion protection, color, or provide texture to objects.

Passivation

An immersion process designed to remove free iron and sulfur from the surface of stainless steel in order to promote longer service life and protection from corrosion. This is NOT a pickle or descaling operation for the removal of heat treat tint or weld scale.

Phosphate

Phosphate coatings consist of a crystalline conversion coating on steel substrates for use as a pretreatment for other coatings or as a break-in lubricant. Phosphates are quantified by coating weight not thickness due to their fragile grain structure.

Pre-Penetrant Etching

During the pre-penetrant process an etch is often used to remove any soft metal smears or residual trace metals left behind from the manufacturing process allowing the indications to be more easily identified. In the case of aluminum, depending on the specification the amount of metal removal is in the .0002” to .0004” range per […]

Primer

The function of the primer is to increase the bond strength of the subsequent topcoat to the surface, increases paint durability, and/or provide an extra layer of corrosion protection.

REACH

REACH is the key chemical control regulation in the European Union. The acronym REACH stands for Registration, Evaluation, Authorization and Restriction of Chemicals manufactured in or imported into the European Union.

Salt Fog Testing

Also called Salt Spray Testing, is described in ASTM B117. The test provides a controlled corrosive environment which is used to generate resistance information for metals and coated metals exposed in the test chamber.

Solid Film Lubricants

See Dry Film Lubricants

Sulfuric Acid Anodize

(SAA) Meets MIL-A-8625, Type II and Type IIB. This is the most frequently designated anodize system and is a RoHS compliant coating.

Teflon™

A DuPont trade name for Polytetrafluoroethylene. This synthetic resin provides excellent lubricity under light loads.

Topcoat

The topcoat provides the color and the primary function for the coating. Corrosion and wear resistance would be two examples of the function required of this coating.

Trivalent Chem Film

Meets MIL-DTL-5541, Type II. This conductive conversion coating IS RoHS, ELV, and WEEE compliant. The trivalent system is gaining in popularity.

TT-C-490

Type I, Zinc Phosphate is very commonly called out for commercial and government contracts. This coarse grain crystal coating has a coating weight of 400 mg/ ft2 on average.

Wash Primer

A wash primer is an organic coating typically containing phosphoric acid and zinc chromate. The acid provides a slight etch on the part while the zinc provides modest corrosion resistance. This is often followed by a secondary primer and top coat system.

WEEE

Waste from Electrical and Electronic Equipment, or WEEE, was also developed by the European Union. Directed as a recycling endeavor this has a global impact for businesses that choose to do business in Europe or affiliated countries.

Zinc Phosphate

Meets TT-C-490, Type I. It is used to provide modest corrosion protection or as a pretreatment for other coatings like paint.