Surface Finishing Tutorial

#152 Work Steps of Electroplating

Category : Electroplating

March 1, 2013

The working process of electroplating, in an outline, is performed on the following order: Pre work→Pre process→Plating→Post process→Post work

※	Note) Plating method Based on workpiece sizes and shapes, the following plating methods with the workpiece retaining and energization methods are used.

(1) Rack plating

Plating is applied by hanging in the plating solution, with multiple electrical connections secured per each workpiece.

(2) Barrel plating

For small workpieces where rack plating method cannot be used (or not economical), many workpieces are plated by tumbling and energizing in a barrel that is very power saving. However, this method is not applicable for every plating case.

(3) Continuous plating (Hoop plating)

For plating long items such as wire material and hoops (strips), dedicated plating systems are used where the workpieces travel through the system for the complete plating process from pre-process to post process.

(4) Others

Basket plating, Brush plating, Partial plating, etc.

	Plating steps	Work contents
Pre-work	Material pre-machining Fixture mounting	This is a process of applying mechanical conditioning on the material surfaces to satisfy required functionality and appearances prior to plating. Examples: Buff polishing, Honing, Satin finishing to obtain various plated surfaces such as mirror surfaces, matte, satin textures, Spun textures, diamond cut. Fixtures are used to hang workpieces in plating solution and apply electrical current. Barrels are used for small parts.
Pre-process	Alkaline degreasing, Acid wash, Electrolytic cleaning, Acid activation	The basics of the pre-process is to expose the bare surface of the material by removing surface contamination (dirt, dust, oxidation film, oily contaminants, etc.) Therefore, the types, concentrations, process temperatures and times of acids and alkalis are varied according to the materials to be treated.
Plating	Copper, Nickel, Industrial chrome, Gold, Silver, Tin, Various alloy plating*, etc.	For multi-layer plating, this step is repeated as needed. Not all combinations are possible.
Post process	Neutralizing, Chromate process, Discoloration prevention*, Drying	In post processing, plating solutions remaining on workpieces in minute quantities are removed. Furthermore, chromate treatment to improve the corrosion resistance is applied, and anti-discoloration treatments on copper and silver platings are applied. Water removal from the workpieces are also performed.
Post work	Fixture removal, Baking, Painting & etc. Inspection, Packaging	When the processed material is of the type that occlude hydrogen during the acid wash and plating processes such as carbon steel, heat is applied immediately after the plating to purge the occluded hydrogen (baking). For ornamental platings with chromatic colors, some are painted (clear, colors). Gold color plating, Pearlescent nickel, Antique, etc.

* marked process is followed by a water washing step.

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