Friction Welding Problem # 1
Better Served by Forging and Other High-Volume Processes
We love to talk about the advantage of near-net shapes. There are a variety of ways to create them. Among those methods are certain processes like forging and casting. Both offer excellent efficiency in creating near-net shapes. If you have high-volume parts to produce in the thousands on a regular basis, those may be better choices than friction welding if your program will support the upfront die investment and the logistics of handling thousands of parts per lot.
Friction welding requires a machine setup, sometimes a tooling investment for work holding, saw cutting of bar-stock, a special facing of the weld surface in some cases, and removal of the weld flash to create near-net shapes comparable to castings and forgings.
As a source for near-net shapes, friction welding works best when the part program does not support the flow of thousands of parts at a time and an upfront die investment would be too much. If your parts are consumed in lots of 50 up to several hundred to meet demand on an “as ordered” basis, then friction welding might be the perfect solution for you.
Friction Welding Problem # 2
As found on CNC Machines Cutting Small Quantities From Bar-Stock
If you cut specialized parts from oversize bar-stock in your machine department, you might be tempted to consider starting with a near-net shape. Lacking the volume to forge or cast, friction welding might come to light as a possible solution. Although friction welding is a great idea for work consumed in smaller volumes than forging or casting lots, the cost of using it may exceed the budget for small, limited use part orders.
When you add up the cost to implement friction welding, it often cannot be supported unless there is some ongoing demand to amortize tooling for work holding and job-lot setup on each order.
There are times when a specialized part order can be justified for friction welding. This happens when a bi-metal fusion of material is required. There is no better way to create bi-metal components. Other times the strength of friction welding is necessary for joining complex shapes that cannot be machined from single pieces of bar-stock or billet. If you require bi-metal combinations or full-strength bonding of complex shapes, you may have an exception to the small, custom limitation of friction welding.
Friction Welding Problem # 3
Not All Parts Require The Full Strength Bond of Friction Welding
Traditional welding methods that are conducted by hand or machine will create joints with a weld at the perimeter of a joint. They do not equal the strength of a full surface fusion of material. However, traditional methods are often strong enough for a given application and can be produced economically.
Some industries like hydraulic piston cylinder manufacturing relied on those traditional methods for decades. In recent years, friction welding has been growing as the specified norm for these joints. The trend behind the change is a drive to eliminate variables of handheld processes and stabilize costs with a repeatable, computer controlled method. Friction welding makes that possible. Strength is almost a side-effect of this trend. It is a welcome side effect, but not always the driving factor.
Should You Rule Out Friction Welding?