FAQs - Frequently Asked Questions

Q: My metal-weld tooling wears out much too quickly. What can be done to remedy this situation and extend tool life? 

A: The key is in determining how the tool wear occurred. A close physical examination and metallurgical analysis of a worn tool is required before steps can be taken to elevate the tools performance. When designing tools for ultrasonic metal welding, there are a number of metallurgical properties that must be considered. Of these properties, the ones that specifically relate to tool life, and particularly to a tools wear characteristics are: hardness, toughness and wear resistance. These characteristics can be modified by heat-treat processes and enhanced with post-manufacture surface treatments. 

Sonic Tool Company has successfully implemented a number of actions that resulted in improved tool performance. Some modifications were as simple as changing the weld pattern to better match the application. Other changes involved a metallurgical analysis to help us evaluated the wear characteristics of the existing tools and implement engineering changes via material and surface treatments to yield a more durable tool with longer life.

 Q: I weld aluminum parts and a major problem is aluminum sticking to the horn and anvil. Why does the aluminum stick and what can be done to prevent this? 

A: During the ultrasonic metal weld process the weld pattern of the horn, which commonly consists of knurled teeth, moves back and forth across the surface of the aluminum while applying the pre-set weld pressure. The mechanics of what the weld pattern is exposed to during this process is very similar to the mechanics of a tool bit that is used to "dry machine" aluminum. Aluminum has a natural tendency to stick to a conventional machine bit. This phenomenon is called "soft metal pick-up". 

Soft metal pick-up has always been a major problem in machining, which forced the tool-bit industry to conduct significant research into the why, how and prevention of the phenomena. Although the problem has never been totally eliminated, several solutions to "minimize" the situation have been developed and Sonic Tool applies this technology to the manufacture of ultrasonic metal-welding tools. Some corrective actions we employ include choosing the appropriate tool steel from which to manufacture the horn or replaceable tool tip, employ post manufacture tool surface treatments or coating and, equally important, determine the proper application parameters.

Q: I have a problem with horns breaking. Can they be made more robust? 

A: Certainly. The solution however requires an examination of the damaged tool and an understanding of how it was used in production. Tool damage can result from a number of factors, including: 

    · The horn coming in contact with part of the weld fixture. 

    · Replaceable weld tips incorrectly installed 

    · Unacceptable weld parameters (excessive amplitude and or weld pressure)

    · The tool was manufactured with undercuts, relief's etc, all of which are in 

      essence, stress risers. 

While working closely with clients to identify the cause of tool failure, we have identified steps to correct these problems. Solutions include: 

    · Readjusting or modifying weld fixtures and/or weld parameters 

    · Conduct operator training to ensure tooling is installed properly 

    · Redesign existing tool geometry to minimize stress risers 

    · Use appropriate metal for the horn in order to provide a more robust tool 

    · Implement a totally new tool design

If you have an ultrasonic metal-welding problem and would like another opinion on how the problem might be solved, or the process itself enhanced, simply click on our email address, state your concerns, and send it off to us. Chances are we will get back to you in a matter of hours. 

engineering@sonic-tool.com