Focus: Sonic Welding

Summary: Sonic welding is a secondary operation that has proven itself to be a strong, easy, and efficient method of joining two separate plastic parts or components.

For sonic welding to be most effective, each part should have a smooth, even surface along which the weld will be formed. The process works by using high frequency sonic energy to vibrate the two part surfaces against each other. The resulting friction causes enough heat to actually melt a small amount of plastic on each surface. When the plastic re-solidifies it creates an extremely strong bond. The entire process for each weld takes only a fraction of a second.

Our secondary operations team sonically welds literally thousands of parts every day. The example shown above is a pulley that is marketed by our Powerline division. A plastic cap is welded to the face of the pulley to keep the bushing and bearing assembly in place. These pulleys are designed for use in the exercise equipment industry and as such they must be able to withstand punishment. The cap welded to these pulleys has been tested to withstand a lateral force of about 1000 lbs.