Plastic Assembly News

Machine Troubleshooting


1. Begin by pushing the test button to see if the power supply overloads when running the converter, booster and horn in air.  If the power supply overloads in air, remove the converter, booster and horn from the welder and inspect the assembly carefully. Look to see if there are visible cracks, check to see if the horn is properly torqued to the booster and if the booster is properly torqued to the converter and then check to see the interconnecting studs are properly torqued. Loose horns, boosters and studs will cause overload conditions. If the stud is loose, torque the stud to 290 in-lb for 3/8-24, 450 in-lb for 1/2-20 and 70 in-lb for 8mm stud.  If the horn or the booster appears loose, tighten to these torque specifications: 220 in-lb for 20 KHz and 95 in-lb for 40 KHz.  If either of these components appears cracked, contact us at 317-841-1202 or  A word of caution is in order.  It is possible that you cannot visibly see a crack, but a crack does exist.

2. If everything appears to be okay in step 1, disassemble the converter, booster and horn. Make sure the mating surfaces of the converter, booster, and horn are clean. Check to see if there is a .003 thick Mylar washer between the interfaces.  If so, remove the washers. (Note: if the washers were in place it is likely that the interfaces will be clean.)  If the surfaces are not clean, wipe the interfaces with a soft cloth or paper towel. If the interfaces show pitting or residue buildup, they will need to be resurfaced. To resurface, remove the studs that connect the booster to the converter and the horn to the booster.  Place a sheet of 400 grit emery cloth to a flat surface and pull the component with the worn surface against the emery cloth.  The component should be pulled in a straight line, not in a figure 8 or other pattern, and held perpendicular to the emery cloth.  You should recondition the components by pulling in one direction only and then rotating the component 120 degrees and re-stroking.  It is not necessary to apply pressure as the weight of the converter, booster or horn should be sufficient to provide the needed force.  This process should be repeated until most of the pitting or residue is removed and this is usually accomplished within a few rotations. Note: It may not be possible to remove all of the pitting.  You don’t want to remove all of the craters if the pitting is deep because these are tuned components and too much removal of material will alter the frequency. Once you have the interfaces clean, the converter, booster and horn should be reassembled.

3.  Before reassembling the converter, booster and horn, inspect the interface studs that were removed in step two above. It is possible that these studs have failed and will need to be replaced. If the studs are in good condition they can often be reused, but this is a great opportunity to replace the studs if they are available.  Reinstall the studs using the specifications provided in step 1. The interfaces between the converter and the booster and the booster and the horn should be treated before reassembling.  If you have Mylar washers available, this would be the preferred way of protecting the interfaces.  Place one Mylar washer over the stud of the booster and one Mylar washer over the stud of the ultrasonic horn.  A bag of Mylar washers can be purchased from Plastic Assembly Technologies, Inc. for $10.00.  If Mylar washers are not available, you should use a small amount of silicone grease between the interfaces.  Be careful not to apply the silicone grease to the mating studs.  Reassemble the converter, booster and horn assembly and retest the stack for the overload condition.

This post will be updated frequently in an effort to provide you with additional information on machine troubleshooting. Please check back for more updates. Thanks for visiting.

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