Friction Welding – Is it Feasible for You?

Posted January 15, 2015 In Process Technology

Friction Welding “Petal Test”

Showing samples from a friction weld development “Petal Test”

I saw this terrific post called 7 Advantages of Friction Welding from Mr. Miles Free of The Precision Machined Products Association (PMPA).

Friction welding is a lesser-known joining process that often meets with mystified expressions — even when talking to experienced engineers. Origins of the process go back well over a century and it has been a proven part of manufacturing for over 50 years. Customers who learn about friction welding approach us seeking improved efficiency in part fabrication. Excitement runs high when people discover the friction welding process, so we walk them through a screening process to check feasibility. There are some basics that must be met before proceeding with friction welding.

Basic Qualifiers for Friction Welding include:

  • Economics
  • Part Configuration
  • Material Choices
    (The combination of dissimilar metals is especially interesting.)

Let’s look at the economics.

  1. Friction welding can save material. As a result, significant money can be saved – especially when that material is rare and/or expensive.
  2. Friction welding can save machine time. But, can we save enough?
  3. Parts that have a strong diameter contrast between sections are great candidates if the alternative is turning the shape from bar stock to the maximum diameter. Diameter change over extreme length also contributes to feasibility.

Combine high-cost materials with strongly contrasted diameters and you have a textbook candidate for friction welding.

Part Configuration

Part configuration is an important issue. Friction welding is more like forging than traditional welding because we apply extreme pressure to force a fusion of the material. To apply that force, we need to work with parts that can bear the axial pressure. Therefore, we primarily look for components that connect end-to-end in a concentric fashion. With tooling, we can accommodate asymmetrical setups such as a block-to-rod. In most cases, the faying surfaces must be flat. They should be parallel to each other and perpendicular to the axial force.

Friction Welding Material Combinations

Material combination is fascinating because we can join dissimilar metals. The varieties and uses of bi-metal products could be subject to another post. Keep in mind though, like traditional welding, we need to avoid alloys that contain lead, sulfur, or graphite. We do work with customers to find substitutions. For example, lead content is often specified to ease machining and extend tool insert life. If the purpose of friction welding is to reduce machining time, then the lead content may no longer be necessary.