Plating metal onto plastic materials is a process that originated in the 1960s in the automotive industry. Manufacturers had started using plastic parts and components to make vehicles lighter and more fuel efficient. They discovered that applying a coating of metal, such as nickel, to these parts would enhance their durability and increase their aesthetic appeal. In the ensuing decades, industries such as electronics and plumbing have also adopted the practice.
While plating onto plastics is now widespread, the process is more complicated than typical metal-on-metal plating applications. Defects frequently occur, especially if the metal finishing company has little experience with the technique. Examples of some of the more common flaws include:
- Poor coating adhesion: Metal does not adhere to a plastic surface very well without proper surface preparation, and it becomes even more problematic if the plating bath contains excess levels of chromic acid.
- Flash: Flash occurs when metal accumulates on protrusions on the plastic component. This can create sharp edges that result in fitting and appearance issues.
- Scratches: Many forms of plastic are delicate, which makes the workpiece susceptible to scratching during plating. Scratches can occur at any stage of the plating process, which underscores the importance of handling the substrate with care during every phase.
- Warping: Plastic can also warp easily during plating. Common causes include exposure to extreme temperatures (often resulting from the failure to maintain the appropriate bath temperature), not “racking” the part properly when performing rack plating or general mishandling of the plastic workpiece.
- Roughness: A rough surface is usually not desirable when plating onto plastic. Unevenness can occur due to the presence of particles in the plating bath, which often indicates inadequate filtering practices.
Steps for Minimizing the Risk of Plastic Plating Defects
Careful planning is a vital troubleshooting step when plating onto plastics and should begin well before plating. For example, manufacturers of plastic parts and components can play an active role in preventing many common defects during the product design phase. Eliminating sharp edges, avoiding deep recesses that make it difficult for the plating solution to reach and ensuring sides of the product are not overly thick can all have a positive impact on the plating result.
It’s also vital to understand the characteristics you want your plastic workpieces to exhibit after plating. Each metal has distinct properties that will impact the plating outcome, so it’s essential to choose the right one for your processes. Factors to consider during metal selection include electrical conductivity, thermal performance, wear resistance and flexural strength.
SPC has the plastic plating expertise you need to achieve the optimal outcome for your projects. Contact us for more information and a no-obligation quote today.
