Third Party Inspection of Zn Plated Products
Third Party Inspection of Zn Plated product – In this Technical information – we have explained the followings related to Zn Plating / Zn Plated Products
- About Zn Plating
- Zn Plating Process
- Application of Zn Plated products and its Benefits
- Inspection / Check Points
- Reference IS Standards for Zn Plating
- Defects of Zn Plating
- Inspection and Testing procedures for Zn Plating products/ Process
- Instruments used for Inspection and Testing
The purpose of providing this information to develop sound understanding and knowledge on Third Party Inspection of Zn Plated products / Zn Plating process. So that inspector performing Third Party Inspection services can apply knowledge to perform the Third-Party Inspection of Zn Plated products / Zn Plating process and provide the optimum output of Inspection of Zn Plating process/ Zn Plated Products.
Zinc plating, a process also known as galvanization, is the deposition of a thin layer of Anti Corrosion on the metal component to provide a protective layer. The outer surface of the zinc coating oxidizes to form zinc oxide, which results in a matte silver-color finish.
Zinc Plating is primarily used to protect metals from corrosion effects. Zinc coating prevents corrosion of protected metal by forming a physical barrier. Zinc and iron/ steel are joined and placed in an electrolyte a cell is formed in which the zinc becomes the anode and the steel the cathode. Then, the zinc is sacrificed, and the steel does not rust.
Process of Zinc Plating
- Cleaning of Surface: –This is done to eliminate any rust, oil, and dirt from the components. It’s best to use an alkaline detergent to ensure the zinc plating remains intact for a good period of time. The cleaning process involved putting the metal in a bath for 5-10 min at 150 to 200◦ F to take out the dirt. This is followed by an acid treatment that helps eliminate surface rust.
- Preparation Of Plating Solution: – zinc plating requires immersion of the component into a unique electrolyte solution(Acid zinc, Alkaline zinc etc), which is also known as a plating bath. The bath consists of the zinc metal ionic solution and various chemicals that facilitate the plating process. They also help produce the desired chemical and physical properties of the finished product.
- Choosing the Zinc Plating process: -After Solution preparation, the parts are ready for plating The chosen method could involve rack plating where larger parts are fixed to a metal rack which is placed inside the tank. Barrel plating is normally used for smaller parts; the parts are placed inside a barrel and rotated.
- Introducing the electrical Current: – Electroplating is also known as electrodeposition because an electrical current is used to deposit metal ions onto the surface of the components.
- Post- Treatment Procedure: –Completion of electrodeposition, the parts ready for post-treatment. This involves rising the parts in water to remove any contaminants and plating bath remnants. The final step is to dry the zinc plated parts
Factors Impacting Zinc Plating Results
- Current Density: -The current density significant impact on the thickness of the zinc coating. If higher current density, the greater the thickness coating.
- Temperature: – The temperature of the plating bath will also have a direct impact on zinc plating coating. Higher bath temperature increases the consumption of brighteners and other additives.
- The concentration of Zinc Deposit: The level of zinc concentration in the plating solution will affect the brightness and texture of the plated product. A higher concentration will produce a rougher surface, while lower concentration results in a brighter finish.
- Other controllable factors that affect the result
- Components Surface Condition
- Duration of actual plating time
- The efficiency of the rinsing operation
- Position of anode and cathode
Zinc Plating Applications & Benefits
- Zinc Coating can provide a corrosion-resistant coating on smaller and larger parts.
- Zinc coating increases the strength of the components
- Zinc is capable of tolerating temperatures of up to 120◦ F which can help lower cooling cost.
- Zinc is an extremely ductile metal
- Friendly to the environment
- Low Cost
IS Standards for Zinc Plating
- IS: 1572-1986-Specification for electroplated coatings of cadmium on iron and Steel.
- ASTM B633-19-Standard for electrdeposited coating of zinc on iron and steel
- IS 10173:1982-Zinc alloy die casting for electroplating
- IS 10209:1982-Specification for electroplated coatings of alloy tin lead
- IS 2633 (1986 )-Method of testing uniformity of coating of zinc
Defects in Zinc Plating/ Zn Plated Products
- Cold Shut
- Sharp Edge
- Cleavage Points
- Unclean Manufacturing
- Loss Of Adhesion
- Cracking After Plating
- Dull and hazy Deposits In Plating
- Blistering in plating
- Oxidation in plating
Inspection and Testing Procedure& types of Zinc Plating
- Sampling- The number of sample to be tested shall be as specified in material specification.
- Preparation of Test Piece-A test piece shall be cut off from a sheet selected as per material specification.
- Cleaning of sample-The test piece shall be cleaned with volatile organic solvent
- Copper sulphate solution preparation-The specific gravity of the test solution during the test shall be 1.186 at 18 ± 2◦ C. Adjustment may be made by adding distilled water.
- Interpretation OF Test-Specified the number of dips, when the test piece is finally rinsed and wiped dry, it does not show any adherent red deposited of copper upon the base metal.
- Number of Dips-The sample shall be subjected to four successive dips in the solution, each lasting one minute.
- Supplementary Test (Microscopic Test)-The test piece through the copper deposit, mounts and polishes it metallographically.
- Qualitative Test for Zinc-Apply a drop of dilute hydrochloric acid to the area in question (depending on its size).
- Water Immersion Test-Partially immerses the test piece in distilled water at room temperature.
Instruments Used for Zinc plating Inspection
- The universal tensile testing machine
- Salt Spray chamber
- Adhesion test chamber
- Elco meter
- Knife for knife test
Most Common Intended use of Zn plating products
- Automobile Parts
- Machine Parts
- Industrial Use
- Home Appliances
Third Party inspection Agency in India
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