To get the best results from your ultrasonic plastic welding equipment, you are going to need to test and tune it regularly. Here is everything you need to know to test your ultrasonic converters, stacks, and boosters and tune your horns.
5 Tips on How to Tune and Test Your Ultrasonic Stack
1. Tuning Horns
Ultrasonic horns will need to be tuned to the proper frequency to compensate for new parts with unique elastic properties and milling variations. Additionally, tuning both new and used horns will provide them with a longer lifespan. To tune your horn, you will use machining tools to grind it to the appropriate size. As you work, be sure to match the horn's frequency to that of your booster and converter accommodating for parts compatibility.
2. Testing Converters
The mechanical quality factor must be at least 250 Qm regardless of frequency, power, or manufacturer variations. This number is always a good rule of thumb to keep in mind when performing testing on this part. Basically, testing the Qm involves seeing how many times the converter oscillates after the machine is turned off. Those with a higher Qm vibrate more efficiently and dissipate a lower energy fraction. Note, Qm can vary from part to part, but the higher it is, the more efficiently your machine is running.
3. Testing Boosters
If the converter fails during testing, you will need to repair it before moving to this step. However, if the converter passes, you need to test the booster next. To start the testing process, attach the booster to a working converter following the manufacturer's procedure. Then, run a test looking for a Qm of at least 700. This number is for both the converter and the booster. Be sure to run this test on a welding machine. This can detect if there are any problems with o-rings or bushings. Also, check that the nodal region is coinciding with the holding region.
4. Testing Stacks
If the booster fails, you need to repair it before testing the complete stack. However, if the booster passes, your ultrasonic stack problem is in the horn, which you will test through the complete stack. To start this test, ensure the entire stack is assembled properly. The Qm of a complete stack must be at least 1000. A lower Qm indicates that there is a problem in the stack, likely the horn. If you find a lower Qm, check the horn for any cracks and make sure it is properly tuned.
The best way to ensure a high-quality weld from your ultrasonic stack or ultrasonic converters is to test and tune it. Tune your horn and then run through these steps to ensure that your parts are all functioning optimally.