ultrasonics
Ultrasonic welders with servos rather than air cylinders began to appear by about 1990 but the advantages servos could bring to the process were not well understood at all. The major advantage of a servo welder is precise control of … Continued
Beginning in about 1985, ultrasonic welders began to be equipped with linear encoders measuring weld distance. It quickly became apparent that the two main methods would be absolute distance, giving the same functionality as an end-of-weld limit switch but with … Continued
In the 1980s, pneumatic-clamped ultrasonic welders evolved from controlling only trigger force, clamp force, and exposure time (and amplitude by way of boosters) to a variety of strategies. The first of these was welding by energy. From a machine design … Continued
Many sizes and shapes of parts can be ultrasonically welded, but it is important to follow a few rules. First, energy transfer from the horn/sonotrode to the joint area, as well as support from the fixture, are critical to obtaining … Continued
A shear joint by its very nature creates side load, and so it is best to include some kind of guide wall to prevent parts from distorting during the welding process. Energy directors also benefit from use of guide walls. … Continued
Energy directors are effective with most thermoplastics, but some less so than others. Amorphous materials are generally easy to weld and once softened will generally retain enough heat while traveling away from the energy director to bond when clamp force … Continued
Ultrasonic welding is facilitated by providing an acoustic weak spot in the joint of the parts called an energy director. This is analogous to a fuse in an electrical circuit. From an acoustic standpoint, what is desired is point contact; … Continued
Materials that are too soft to ultrasonically weld can be made stiffer by the addition of mineral (such as talc) or reinforcement (such as glass). Ten percent seems to be a good starting point for experimentation if this seems to … Continued
Polymer materials consist of long-chain molecules. These molecules are many hundreds if not thousands of times longer than their width. They can be visualized as human hairs, and are usually illustrated by lines. Thermoplatic materials come in two general groups: … Continued
In order to weld a thermoplastic part using ultrasonics, four factors must come together. First, the material must have a sufficient loss modulus. This is a very fancy way of saying that material must be able to be heated by … Continued