Coating and Plating Specifications

PROCESS

METAL

APPLICABLE SPECIFICATION

NORMAL COATING

THICKNESS AND COLOR OR APPEARANCE

REMARKS

ALODINE

See CHEMICAL FILMS

ANODIZE –

CHROMIC ACID

ALUMINUM

ANODIZE –

SULFURIC ACID

ALUMINUM

0.00007-0.001

Clear

All Colors

Not to be applied to assemblies or

part with joints or recesses which might entrap solution. Good electrical

barrier and paint base. May be dyed in all colors. Dichromate seal

will impart yellow color. Produces excellent decorative finishes

when the part is either polished, brushed, or bright dipped prior

to anodizing. Good abrasion resistance.

ALUMINUM

alloy and thickness.

and 50% buildup. Excellent dielectric and heat absorption properties.

Should be considered for salvage applications. Sealing greatly increases

corrosion resistance, but slightly reduces wearing qualities. Teflon

sealing may be added to increase lubricity.

ANODIZE –

DURASEAL

spray tests that have withstood 1,000+ hours without pitting on 6061

and 2024 aluminum alloys.

ANODIZE –

ARCHITECTURAL (Kalcolor process: also called Bronze Anodize)

Non-dyed integral-color is lightfast and depends on alloy used. CLASS

I is recommended for exterior applications and CLASS II for interior

applications.

ANODIZE

PRINTING

ALUMINUM

anodized background. The letters are of one color and the background

of another. Superior to regular ink printing because of the corrosion

and solvent resistance of anodize, and is an excellent alternative

to engraving.

BAKING

improving the adhesion of plating the base metal, and increasing the

hardness of plating.

BLACK OXIDE

series stainless steels with CLASS 4 coating. Used where a black surface

and low light reflection is required. Supplementary wax or oil dip

(VV-L-800 Preservative Water Displacing Oil) Will improve appearance

and corrosion resistance. Good for decorative purposes when base metal

is polished before processing protection is included.

BLASTING

(includes glass bead and powder blasting)

of metal removed will depend on media selected. May be used for decorative

and optical finishes. Provides uniform matte finish before decorative

processing.

or baked enamel.

Used for cleaning metal before welding and pressure testing

chromate    treatmentTYPE III – With    supplementary

phosphate    treatment

TYPE II – Gray

Dull to bright

resistance. TYPE I coating is very susceptible to stains and fingerprints.

TYPE II coating is excellent for resistance to moisture and humidity,

and a paint base. Chromate colors besides gold are clear, black, and

olive drab. TYPE III is a good paint base. Stress relief is required

on metal with a hardness of Rockwell C34 or above before plating and

hydrogen embrittlement relief is required on metal with a hardness

of Rockwell C36 or above after plating.

corrosion where low     electrical resistance is     required.

Electrically conductive. Normally gold color unless otherwise specified.

CLASS 3 coating is used primarily for low electrical resistance contact

and has less corrosion resistance that CLASS 1A coating.

(hard)

coating is put on either the base metal that is polished or as is.

TYPE II satin coating is put on the base metal that is either blasted,

grained or brushed. Hard chrome is plated directly on the base metal.

Parts requiring heavy metal deposits should be overplated and ground

to the final finished dimension.

plated metals to improve adhesion, corrosion resistance, and to increase

electrical conductivity (CLASS 2). Under tin plating to prevent base

metal migration into the tin to poison solderability (CLASS 3 and

CLASS 4)

machining, shipment, and storage. My be used as a paint base.

May be applied to all alloys except EK30A, EK+1A, EZ33A, HK31A, M1A,

HM31A, HM21A, and LA141A.

non-reflective black coating.

Hard non-conductive coating. Castings should be picked, prior to machining,

to remove scale and insure uniformity of the coating. The coating

thickness is approximately 40% penetration and 60% buildup.

surfaces that have been remachined or abraded.

bake enamel to preserve brightness.

base and has low electrical resistance.

nickel adhesion

Exceptionally good for salvage purposes. Good corrosion, oxidation,

and wear resistance. Facilitates soldering on aluminum and brazing

on stainless steel. CLASS 1 and CLASS2 coated steel parts. Rockwell

C33 or above, are baked for hydrogen embrittlement relife. CLASS 2

coated parts are additionally heated to 450 degrees F. or more, to

harden the nickel deposit. This heat treatment should increase the

plating hardness to 800 Knoop or better, for CLASS 2 coatings.

satin finish, etc.

   TYPE III – 99.9% gold min.

GRADE A (only)

CLASS 4 – .0003 min

CLASS 5 – .0005 min

CLASS 6 – .0015 min

Dull to bright

on a copper rich surface such as brass, bronze, beryllium copper,

copper strike or plate, a nickel underplate is applied to prevent

diffusion of the copper and the gold. Coating thickness of .00005

– .0001 is best for soldering.

dichromate post treatment

TYPE II – Heavy coating

CLASS A – Hard brown coating

GRADE 1 – No post treatment

GRADE 3 – With bifluoride-

     dichromate

post treatmentGRADE 4 – With bifluoride-      dichromate

post treatment including      moist

heat aging

GRADE 5 – Same as GRADE except      double

bifluoride-dichromate post      treatment

coating for magnesium in existence. The coating thickness is approximately

35 to 40 percent penetration and 55 to 60 percent buildup. When selected

organic post-treatments are applied, a salt spray test of up to 1000

hours is possible. The coating is non-conductive. TYPE II coatings

have extremely good resistance to abrasion. TYPE I light coatings

are normally tan in color. TYPE II heving coatings will range from

an oatmeal color to dark brown, depending on the thikness of the coating.

HAE coatings are not affected by extream tempurature variations. A

heavy coated panel heated to 1075 degrees F. and plunged into ice

water will show no ill effects to the coating. This process can be

selectively applied by masking the areas that have to be free of coating

for: electrical grounding, close tolerance dimensions, heavy buildups

for salvage purposes, etc. The coating may be used on all magnesium

alloys.

are expressed in the Rockwell superficial bardness of metallic materials.

Hardness values for nonferrous alloys do not give absolute correlation

with mechanical properties, as with ferrous alloys. Hardness testing

on nonferrous alloys should be used to detect incorrect heat treating

or damage caused by maching. Conductivity testing uses electromagnetic

introduction to test physical properties such as hardening, anneling,

changes in alloy composition, heat treating, and aging, etc.

that won’t take Dow #7. Careful control is necessary to avoid etching

of base metal.

flaws, and dicontinuities on the surfaces of ferromagnetic materials.

&nbsp &nbsp GRADE E – .0006

&nbsp &nbsp GRADE F – .0004

&nbsp &nbsp GRADE G – .0002

CLASS 2 – as specified

or hard form, dull or bright finish. Corrosion resistance is related

to the thinkness applied. Low thermal expansion. Slightly magnetic.

CLASS 2 plating will be .002 to .003 thick unless otherwise specified,

but may be controlled to fit any engineering application. CLASS 1

coatings that include copper undercoat are used for decorative chromium

systems. Embrittlement relief is required on all metals with hardnesses

above Rockwell C40.

enamels; vinyl and acrylic lacquers; varnishes and resin coatings;

epoxy, acid-wash, red oxide, and zinc chromate primers. Finishes such

as class A, hammertone, wrinkle, and texture. Also, see SOLID

FILM LUBRICANT.

solution&nbsp  TYPE VIII – Medium temp. high     concentration

nitric acid solution

scrapings, chips, etc., that will cause rust or stain spots if they

are not removed. A thin, transparent passive film forms over the surface

and prevents this condition from occurring. The presence of rust and/or

heavy heat treat scale may necessitate a pre-pickle. For the 400 and

precipitation hardening series of stainless steels, the proper heat

treatment is very important to ensure complete passivation. Our inspection

personnel conduct the required copper sulfate, salt spray, and water

immersion inspection tests in our own testing department and chemical

laboratory in accordance with MIL-STD-753 and ASTM B117. (see

TESTING).

METHOD C – Solvent      removable

METHOD D – Post emulsifiable      (hydrophilic)

can, however, be useful on other metals and materials. Detects cracks,

discontiuities, corrosion, welding flaws, laps, cold shuts and porosity.

Prepenetrant etching is performed on aluminum and magnesium parts.

Critical surface finishes and areas with close tolerances are masked,

as required, to protect them from metal removal, prior to the etching

operation.

preservativeCLASS 2 – MIL-C-16173GRADE 1 preservative treatmentCLASS 3 – No supplementary    preservative

treatment

CLASS 4 – Chemically converted

extrusion and deep-drawing applications. Not recommended if the coating

is expected to come in contact with alkaline materials or to be exposed

to temperatures above 200 degrees F. CLASS 2 and CLASS 4 coatings

extend the corrosion protection of the phosphate. MIL-L-3150 oil may

be used as an alternative for very small parts under CLASS 2. CLASS

4 provides an improved break-in coating.

enamel, lacquer, etc. Improves corrosion resistance of the base metal,

and promotes better adhesion between the base metal and the organic

coating. Also, use for post treatment of both cadmium and zinc plating.

or weling. The hazards involved in this process should be investigated

before using.

finishes. Removes surface imperfections.

removable film

Brown to black

leaving a protective film. GRADE 1 is for metals exposed to outdoor

weather, for up to one year. GRADE 2 is for machine parts, indoors

for up to six months. GRADE 3 is for displacing water and protection

of interior parts for up to four months. GRADE 4 is for indoor or

shed storage of parts. Also, where a tack-free or translucent coating

is required. GRADE 5 is the same as GRADE 3 except the film is removed

with hot water or low pressure steam.

epoxy, lacquer, plastisol or vinyl inks. Print on metal anodized,

bare, painted, plated, etc.

treatment

GRADE B- Without supplementary    tarnish-resistant

treatment

of nonferrous basis metals and increasing conductivity of basis metals.005 minimum – See REMARKS

per GRADE A does not impair solderability. Greatly increases conductivity

of lesser metals. Ferrous surfaces require and undercoat of .0005

comprised of copper or nickel or any combination. Nickel undercoat

is advantageous when corrosion protection is important. .005 minimum

thick coating is suggested for electrical contacts depending on pressure,

friction, and electrical load.

MIL-L-85614

film, cadmium plate, blasting if required, etc.).Low co-efficient of friction reduces wear, prevents galling and seizing.

Excellent fluid and corrosion resistance when used in conjunction

with pretreatment.

buildups on worn parts and for salvage purposes.

finishes. The salt spray method is used extensively for testing of

anodize, chemical films, and plated metal coatings. The salt spray,

humidity, water immersion, and copper sulfate methods are used to

check on the passivity of stainless steel after the passivation process.

metal

.0002-.0006 to prevent case forming in    nitriding

TYPE II – .0007 minimum

Dull gray to bright silver.

must be used on brass and zinc alloys. Excellent solderability and

fair corrosion resistance. At room temperature TYPE I dull plating

oxidizes or slowly but bright plating oxidizes less readily. Parts

to be soldered or used for electrical contacts can be protected from

oxide formation by a preservative coating of stearic acid as specified.

TYPE I plating may be fused but thickness will vary after treatment.

A maximum of .0003 thick plating must be maintained to permit satisfactory

fusing. TYPE II hot-dipped coating is used on parts for maximum corrosion

resistance.

coatingsTYPE IV – With phosphate conversion

coatings

SC 2 (moderate)

Fe/Zn 5 (5 microns)-.0002

SC 1 (mild)

TYPE I – Clear

TYPE II – Gold

TYPE III – Clear

TYPE IV – Gray

Dull to bright

does not maintain its bright surface for a very long period of time.

TYPE II and III treatments retard the formation of white corrosion

products on the plated surface. The service life of zinc plating is

a function of conditions such as thickness, exposure, and usage. The

Service Conditions are as follows: SC 4 – Very Severe: Exposure to

harsh conditions, or subject to frequent exposure to moisture, cleaners,

and saline solutions, and damage by denting, scratching, or abrasive

wear. SC 3 – Severe: Exposure to condensation, perspiration, infrequent

wetting by rain, and cleaners. SC 2 – Moderate: Exposure mostly to

dry indoor atmospheres but subject to occasional condensation, wear,

or abrasion. SC 1 – Mild: Exposure to indoor atmospheres with rare

condensation and subject to minimum wear or abrasion.