A wide range of custom metal stampings require metal plating as part of the finishing process  – from large automotive parts to miniature components for electronics, injection molding, medical devices, and other applications. Metal plating for precision stamped parts is frequently used to strengthen electronic connections, but plating also may be used for decorative purposes and for corrosion resistance.

Designing the Stamping for Cost Efficiency
The design of the metal stamping itself needs to take into account the type of metal plating that will be required to enhance the part’s appearance, wear and functionality, as well as the metal material to be used for plating. For precious metals in particular, the cost of the plating material plays a significant role in the overall cost of the part.

OEM engineers can benefit from consulting with metal stamping engineers to ensure that the stamping can be designed to minimize material waste and maximize the performance of the metal plating and the part itself. Metal stamping firms can provide guidance upfront on DFM for the part and recommend the best plating process. For example, if only a small portion of the part will be visible to the end user, only that part of the stamping may need to be plated for appearance purposes.

Types of Metal Plating for Stamped Parts
Pre-plating 
Pre-plating treats all of the raw material before stamping, which is typically less expensive than plating each individual part. However, pre-plated material is likely to be affected by the stamping process, resulting in un-plated areas such as edges and sides, which may require further operations to meet specifications.

Spot plating
Spot plating is often chosen when precious metals are required for electrical conductivity to minimize the use and expense of the material.

Post-plating
Post-plating is performed after stamping to improve the appearance of the part or its function in harsh environments. Parts that are plated on a reel-to-reel carrier will have bare areas, where the carrier is cut away from the part, which should be taken into consideration upfront.

Some metal stamped components also require an initial stamping, followed by plating, and ending with another stamping operation. This also is done to reduce the cost of precious metals or to reduce the exposure of bent terminals in the barrel plating process. It can also be an advantage if the manufacturer wants to form and cingulate the parts at their facility to feed into their automation.

Plating with Precious Metals
According to Vince Azzano, director of technical sales for Precision Plating Company in Chicago, manufacturers may specify metal plating to microscopic levels as small as 50 to 100 millionths of an inch when used for electrical connections. He explains that the most popular precious metals for spot plating for electrical conductivity are gold, silver, and palladium (a noble metal in the platinum metals group). “Noble metals don’t oxidize and are good conductors of electricity,” he says.

The metal stamping itself may be made of a non-ferrous metal such as copper, with the precious metal plating only used for the connection point. “These metals are often used for applications that require high reliability for product safety, such as sophisticated electronics in automobiles for collision mitigation,” he adds. In contrast, plating with non-precious materials, such as copper, nickel or tin, may be appropriate for applications that transmit a signal, such as headlights, turn signals, and radio switches.