Are Surface Finishing Operations Necessary for Custom Springs and Wire Forms?

Curious if your custom springs or wire forms need surface finishing operations such as plating or electropolishing? More often than not, they don’t. When alternatives are available, we advise customers to forgo secondary operations when possible to avoid the inherent risks involved in finishing parts.  

Today, we’ll take a closer look at the benefits and risks of common surface finishing operations, as well as some alternatives to finishing custom springs and wire forms. 

Considerations for Surface Finishing Custom Springs and Wire Forms

First, it’s helpful to understand when your custom spring or wire form could benefit from finishing operations:

• Will it be in a corrosive or high-humidity environment? Secondary operations like plating can add a layer of corrosion resistance to help ensure long-term quality and durability.
• Does the part need to be a specific color or meet other aesthetic requirements? Finishes like wet paint and powder coating add color to springs and wire forms. This is often a consideration if the part is easily visible to the end user in the final application.
• Does the part have other specific functional requirements? Some springs and wire forms require plating to increase or decrease electrical conductivity. Others will require grease and debris removal through a passivation process.

If your custom spring or wire form has any of these requirements, we can work with our trusted vendor network to provide finishing operations including: electropolishing, passivation, wet paint, powder coating, zinc plating, nickel plating, black oxide plating, tin plating, and shot peening.

However, there are risks to applying surface finishes to custom springs and wire forms that can jeopardize quality and performance:

• Tangling. Plating and passivation are typically carried out using barrel plating—which involves submerging the parts into a tank of finishing solution, where they roll and tumble around in a chemical bath—can be rough on springs and wire forms, often resulting in uneven solution distribution and potentially causing the parts to tangle and then deform when untangling. This is particularly a concern with smaller wire diameter parts. Rack plating is a much gentler plating method that can minimize the risk of tangling, though it is not cost-effective compared to barrel plating. 
• Arcing. During electrically conductive finishing processes like barrel plating, electrical currents can jump between spring wires, damaging the plated surfaces. Arcing—a type of damage characterized by bubbling welts and rough surfaces—can ultimately lead to breakage.

• Hydrogen embrittlement. In a poorly controlled electroplating environment, hydrogen ions can dissolve into metal during the finishing process, causing the part’s chemical makeup to change. This transformation may result in cracking—known as hydrogen embrittlement—which weakens the molecular structure of the spring. Baking the parts post-plating helps prevent hydrogen embrittlement. We always recommend baking after plating, however this also increases production costs. 

It’s possible to mitigate most of these risks by working with a spring manufacturer that partners with exceptional finishing suppliers – which we do here at Orlando Precision – but there are alternatives to finishing that may be a better option for your application. 

Alternatives to Finishing Custom Springs and Wire Forms

If you need your custom springs or wire forms to resist corrosion, consider using stainless steel wire, which provides corrosion protection comparable to what zinc or nickel plating can offer. 

Another solution is to select pre-plated zinc or galvanized steel wire for your parts. These materials can be difficult to source, but are typically more cost-effective than going the route of secondary surface finish operations. 

If you’ve weighed the risks and determined that you need a surface finish for your custom springs or wire form, indicate the precise specifications using MIL-SPEC or ASTM specs to ensure you receive the exact process that you want. You’ll also need to account for the thickness added by the finishing operation—the spring’s outer diameter will grow slightly, so be sure to factor this added thickness into the part specifications you provide. This added thickness is typically constrained by ASTM specs.

Still wondering if you need a finishing operation for your custom springs or wire forms? Contact Orlando Precision today, and we’ll get your questions answered.