In a recent blog post, Horizon Technology, based in St. Mary’s, Pennsylvania, USA, has discussed the possibility of using friction stir welding as a joining process for Powder Metallurgy components. Although not necessarily thought of when first considering joining methods, the PM parts maker states that in very specific applications, friction stir welding is a viable option.
Friction stir welding was invented in 1991 at The Welding Institute in the UK. As a relatively new joining process, Horizon states that many metal manufacturers have limited or no understanding of its inner workings.
In most circumstances, processes such as sinter bonding, sinter brazing or welding, for example, are recommended for joining PM parts. However, Horizon states that friction stir welding of dissimilar alloys and materials is possible, and sometimes even desirable, if you don’t want to fully melt the lower melting point metal.
Friction stir welding keeps the metal in a state that’s just short of melting. You have an impressive amount of heat input control, which allows for minute adjustments for the end result. The surfaces of the two parts are in very intimate contact and bond well without the risks inherent to melting. The joints are often as strong as the base metal, creating bonds that are reliable enough for use in rotary engine housings.
On the manufacturer’s side, Horizon states that using friction stir welding for joining PM parts also creates a safer work environment, because it creates no toxic fumes. More relevant to the buyer, friction stir welding has minimal tooling needs, which keeps labour and material costs down.
Read the full report on Horizon Technology’s blog here.