Common Problems In The Process Of Ultrasonic Welding

Common Problems In The Process Of Ultrasonic Welding

Date:Jan 18, 2021

Ultrasonic welding, compared to other welding methods, it can accept thermoplastic materials. It has many advantages, including process reliability and repeatability, lower energy use than other joining technologies, saving materials and corresponding labor costs. In the process of ultrasonic welding, what are the common problems? In which aspects?


Ultrasonic problem One: Ultrasonic current overload is abnormal


When the generator sends out an overload alarm, it should be checked as follows:


1. Sometimes the no-load test is normal but not working normally. It may be that the internal sound energy components such as the welding head have changed, causing the sound energy to be transmitted poorly. Here is a relatively simple judgment method: hand touch method. The amplitude of the normal working welding head or horn surface is very uniform when it is working, and the hand feels velvety smooth. When the sound energy is not transmitted smoothly, there will be a feeling of bubbles or burrs on the hand. It is necessary to use the elimination method to eliminate the problematic parts. The same situation can occur when the generator is abnormal. Normally, the input waveform of the transducer should be detected as a smooth sine wave. This phenomenon can also occur when there are spikes or abnormal waveforms on the sine wave. At this time, another pruned acoustic energy component can be used to replace it for identification.


2. Ultrasonic no-load test. If the working current is normal, it may be that the ultrasonic welding head has contacted objects that should not be touched or the parameter adjustment between the ultrasonic welding head and the welding seat has failed.


3. When the ultrasonic no-load test is abnormal, first observe whether the ultrasonic mold is cracked and whether the installation is firm, and then remove the welding head and perform no-load test to eliminate whether the ultrasonic transducer + ultrasonic horn has a problem, one step Step to exclude. After eliminating the possibility of failure of the transducer + horn, replace the new welding head for judgment.


Ultrasonic problem Two: abnormal heating of the ultrasonic mold


Ultrasonic molds will have a certain degree of heat during work, which is caused by the loss of mechanical energy of the material itself and the heat conduction of ultrasonic objects. Whether the heating of the ultrasonic mold is normal or not is judged that when there is no load (that is, not touching the workpiece), the ultrasonic wave should be continuously emitted for more than half an hour, and the temperature should not exceed 50-70℃. If the heat is experienced, the ultrasonic mold is damaged or the material is unqualified. , Need to be replaced; mold temperature is too high usually accompanied by abnormally high ultrasonic current;


Ultrasonic problem Three: abnormal howling occurs in the ultrasonic mold


When the ultrasonic mold has howling, the following reasons should be analyzed:


1. Whether the ultrasonic mold is in contact with objects that should not be contacted;


2. Whether the ultrasonic welding head screws are loose;


3. Whether the ultrasonic mold has cracks;


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