Finishing For

• Electroplating is a method of coating a metal or plastic surface with a metal.


• Electroplates are applied by immersing the object to be coated in a tank containing the proper chemicals dissolved in water.


• The part to be plated is attached to a negative electrical lead.


• Once it is attached to the negative electrical lead it is called a cathode.


• The chunks of metal are called ANODES, and the positive electrical lead is then attached to them. They dissolve in the solution as metal is taken away by plating. But at this point we have metal being removed from the anode and deposited on the cathode – the parts to be plated.

Anodizing

• Anodizing is an operation performed mainly on aluminum. The effect is to develop an oxide coating on the aluminum. Again, this is a conversion coating: the surface is converted from aluminum to aluminum oxide.


• This is called anodizing because unlike in plating, the part to be coated is connected to the anode, not the cathode. The part is immersed in a dilute solution of sulfuric acid, current is passed, and the part is anodized – an oxide coating forms. The oxide coating is harder and almost corrosion resistant than bare aluminum.

Chemical Conversion Coating on Aluminum

• Various other wording in use- Iridite, Alodine (Trade name), Chemical film, Chromate Conversion coating- Clear or Yellow


• Accomplished by dipping clean parts in proprietary Dichromate solution.


• Can be clear or yellow color- specified by user.

Build Up / Dimensional Changes

• Any plating - Thickness of plating per side


• Anodizing - Half the coating thickness per side


• No build up on Chemical conversion coat or Black oxide coating.

It is an electrochemical process that thickens and toughens the naturally occurring protective oxide. The resulting finish, depending on the process, is the second hardest substance known to man, second only to the diamond. The anodic coating is part of the metal, but has a porous structure which allows secondary infusions, (i.e. organic and inorganic coloring, lubricity aids, etc.).

• Anodizing is an electrochemical process that produces thick, nonconductive and tough, second only to diamond, protective oxide coating.
• Porous structure allows to infuse organic, inorganic colors and PTFE (Teflon) based solid film lubricants.
• Anodizing is also referred to as anodic coating and commercially achieved by using sulfuric acid and chromic acid electrolytes.
• Chromic acid anodizing is used to produce thinner corrosion protective oxide coating.
• Chromic acid anodizing is specified mostly for welded and porous cast aluminum structures in the aerospace application as trace chromic acid left during process does not corrode the parts.
• Sulfuric acid anodizing process is used to produce corrosion protective oxide coating for most industrial and decorative applications. Sulfuric acid anodized coating dyes easily producing wide varieties of colors.
• Hard coat anodize is produced at low temperature and high current density using sulfuric acid with special additives. Hard coat anodize is used to produce thick oxide coating, generally 2 mil or 50 Micron oxide coating for mostly abrasion/wear resistant, high heat dissipation and dielectric properties.
• All the anodic coating can be dyed to various exotic colors.
• Anodic coating is covered by various Military, ASTM, AMS, Federal and customer specifications.

Andarn has the capability to perform and certify finishing to the following specifications:

• Black oxide finish can be performed on steel, stainless steel, cast iron, copper and brass
• Black oxide finish produces:
  • No dimensional changes
  • No chipping
  • Retains surface properties
  • Absorbs oil and wax
  • Finish can be exposed to heat without fading
• Work finished and tested to the following specifications in-house.

TRB/Andarn has capability to perform and certify finishing to the following specifications:

• This process treats aluminum to form protective film to prevent corrosion for indoor application
• Used as a primer or bonding coating for paint
• Used to produce conductive coating to prevent corrosion in the electronic applications.
• Coating is also referred to as Iridite, Alodine, Chemical film, yellow chromate.

Chemical conversion coating/Chromate conversion coating/Chemical film/ Iridite/Alodine/ yellow and clear coating on aluminum are covered by following specifications.

TRB/Andarn has capability to perform and certify finishing to the following specifications:

• Passivation is “the removal of exogenous iron or iron compounds from the surface of stainless steel by means of a chemical dissolution, most typically by a treatment with a nitric or citric acid-based solution that will remove the surface contamination but will not significantly affect the stainless steel itself.


• Passivation process removes “free iron” contamination left behind on the surface of the stainless steel from machining and fabricating. These contaminants are potential corrosion sites that result in premature corrosion and ultimately result in deterioration of the component if not removed.


• Passivation process forms an extremely corrosion-resistant Nickel-Chromium mono-oxide layer.


• The type of stainless steel determines the most effective passivation process.


• Bath selection (time, temperature and concentration) is a function of the type of alloy processed.


• A thorough knowledge of the material types and passivation processes is paramount to achieving the desired results. Improper bath and process selection and/or process control will produce unacceptable results. In extreme cases, this can lead to catastrophic failure, including extreme pitting, etching and/or total dissolution of the entire component.

Following represents some of the common specifications and test certified by our organization:

Requirements of Passivate baths in-house to meet Military customer’s specs.
ASTM A-967

Andarn has capability to perform and certify finishing to the following specifications.

• Ability to mask off areas not requiring finish for grounding purpose or close dimensional tolerances or multiple finishes as per customer’s blue print and specifications.
• We can supply you with any basic or custom color requested, complying with federal Standard 595.

ElectroPolish

• Increased resistance to corrosion, Improved surface finish, Attractive appearance, Facilitates sterilization and maintenance of hygienically clean surfaces, Reduces contamination build-up, Used for deburring. There is any Military specification for Electropolish