Purpose of Plating
Why is it necessary to apply zinc plating?
- Ferrous materials are susceptible to rust.
- Insulating iron/steel from the air to protect it against rust = Sacrificial protection (Zinc rusts first)
- White rust (iron/steel with only zinc plating is still susceptible to rust)
- Applying trivalent chromium chemical conversion treatment for stronger rust protection
Basic Process of Zinc Plating (Example)
|Immersion Degreasing||In the immersion degreasing step, a surface-active agent is used to remove unwanted substances, such as grease, adhered to the items to be plated.|
|Rinsing||In the rinsing step, the items to be plated are washed with water in order to prevent the chemical solution used in the preceding step from being brought to the next step.|
|Pickling||In the pickling step, oxide films, dirt, and other unwanted substances on the surfaces of the items to be plated are removed.|
|Electrolytic Degreasing||In the electrolytic degreasing step, the items to be plated undergo electrolysis to improve the effect of degreasing.|
|Neutralization||In the neutralization step, residual substances on the surfaces of the items to be plated are removed by an acid. This also prevents the alkaline degreasing solution from being brought to the plating step.|
|Plating||The items to be plated are immersed in the plating solution to generate a thin metallic layer on the surfaces.|
|Activation||In the activation step, the plated surfaces are activated in order to allow normal chemical conversion treatment.|
|Chemical Conversion Treatment||In the chemical conversion treatment step, the plating is further coated with a thin layer of an oxidized compound or other substances.|
|(Finishing)||In the finishing step, the plated items are processed as needed for the purpose of functional improvements, such as appearance improvements.|
|Drying||In the drying step, the moisture on the surfaces of the plated items is removed.|
Barrel Plating and Rack Plating
The products are put into a barrel that has holes through which water can pass. The barrel is immersed in the solution and rotated during the plating process.
It is possible to process a large number of products at a time, achieving higher productivity compared to rack plating.
Products are hung one by one on racks to undergo the plating process.
Because the products cannot come into contact with each other, this plating process rarely causes scratches or deformation, and it is possible to process relatively large objects that would be difficult to barrel-plate.