ENGINEERING TECH TIPS | 4 April 2025

Metalizing Plastic Parts

Tech Tips from Our Engineers at Bamberger Amco Polymers

How Metalizing Plastic Parts Works

Which method you should chose for metalizing a plastic part depends on factors like cost, the target thickness of the deposited metal, and whether the polymer you're metalizing has good chemical resistance. Each approach involves some specialized equipment, but they also offer unique advantages.

Vacuum Metallization

Also called vacuum deposition, vacuum metalizing is attractive thanks to its low relative cost and the fact that it doesn't require exposure to chemical mixtures. A lack of air (and air pressure) in the vacuum chamber helps lower the boiling point of coating metals and prevents oxidation.

The process works like this: plastic parts are fixed on a turntable inside a vacuum chamber. A filament, usually tungsten, is used to evaporate a metal coating (like aluminum or copper) by heating it to around 1500 °C. ​

The plastic fixture is rotated within the coating's vapor cloud, letting the vapor condense and leaving a thin layer deposited on the part. For more abrasion resistance, a second coat can be applied.

Flame Spraying

A method with a low cost and high material deposit rate, which is useful for creating thick layers quickly.

As the name implies, a handheld device is used to apply metallic powder that's heated and melted using a flame. The flame is fed by a mixture of oxygen and gaseous fuel, which helps to dispense the coating material.​

The coatings achieved with this method are usually porous and rough.​

Arc Spraying

The most cost-efficient metallization method (only requiring minimal training), arc spraying involves two wires of metallic material, which carry direct current.

When the wires touch at the tips, enough energy is produced to melt them. A stream of gas flowing between the wires deposits the resulting molten metal.

Electroplating

This process starts with immersing a plastic part in concentrated sulfuric and chromic acid for etching. Etching covers the part's surface with microscopic holes, which the first layer of metal in the electroless process needs to adhere correctly. Neutralization in an alkaline mixture stops the acids from further degrading the part.

Next, the part is coated with a catalytic film and carefully cleaned. After that, electroless plating applies a thin layer of nickel or copper to promote conductivity for electroplating.​

Electroplating starts with negatively charging the conductive coating. When the part is finally immersed​ in a tank containing positively charged chrome ions, the resulting reaction ensures an incredibly even coating layer.​