What is Plastic Chrome Plating?
Many people make the mistake of thinking that they can only apply a chrome finish to a metal part. However, plastic chrome coating makes it possible to give a plastic part the same sheen as a traditional chrome part.
Plastic Chrome Plating Process
Unfortunately, plastic chrome plating is not as simple as applying a coat of chrome to the part. Typically, we will first coat the part with a layer of copper of nickel through a process called electro-less plating. This means that we do not use an electric current to apply the plating. Applying this coating makes the part conducive, which makes it possible to apply the chrome plating later on.
Think of this like the base coat that you’d apply to wall before painting it. This base coat prepares the part for the electro plating techniques that we use to apply the chrome plating. Without it, we can’t bind the chrome plating to the plastic part.
Typically, the entire process follows the following six steps.
Step 1 – Etching
We immerse the part into a tank that contains a mixture of concentrated sulfuric and chromic acids. During this process, the acid mixture etches a serious a microscopic holes along the surface of the plastic part. It is these tiny holes that will contain the metal coating applied during the electro-less plating process.
Step 2 – Neutralization
Upon removing the part from the acid mixture, we immerse it into an alkaline mixture. This neutralizes the acids to ensure they don’t continue eating into the plastic part. This neutralization is also crucial for ensuring no leftover acids disrupt the plating processes later on.
Step 3 – Catalyzing and Accelerating
We apply a catalytic film to the surface of the plastic part to prepare it for the electro-less plating process. However, before we do that, we must also immerse the part in a final bath that removes any leftover chemicals from the previous processes. This bath also accelerates the film, which means that it will react much more quickly to the metal plating that we apply to the part.
Step 4 – Electro-less Plating
We use the electro-less plating technique described above to apply a very thin layer of copper or nickel to the part. The purpose of this it to make the part conductive, which allows it to accept the chrome plating.
Step 5 – Electro Plating
Upon completing the electro-less coating process, we apply a negative charge to the new metal coating. We then immerse the negatively-charged part into a tank that contains positively-charged chrome ions. These ions get attracted to the negatively-charged copper or nickel layer, which causes them to attach themselves to the part. Upon attaching, the ions revert back to their neutral metallic form. This ensures that the chrome plate layer remains even throughout.
Upon completion of the electro plating process, we remove the part from the chrome and allow it to cool.
Step 6 – Quality Inspection
We conduct a thorough quality inspection on the part to ensure we’ve carried out the process correctly. This inspection examines the evenness of the chrome coating, as well as ensuring that the process hasn’t led to any discrepancies in the part itself.
For large production runs, we use an error tracking process to ensure any mistakes get corrected before they can affect an entire batch.