Quality Control of Welded Joint During Ultrasonic Welding of Plastics

It is shown that the change of the oscillation amplitude of the support is wholly determined by the change of such properties of the welded polymeric material as temperature, deformation, and preload. A review of existing methods of batching the input mechanical energy by time, setting, and a fixed gap during ultrasonic welding is presented. It is proposed that the condition of the welded material between the waveguide and the support sensor should be assessed by the level of energy passed through the polymeric material and measured by the support sensor. The experiments have confirmed the dependence of the support oscillations on the ultrasonic welding time, known as the kinetic characteristic. It can be used to solve problems of the relationship between the duration of the welding pulse and the condition of the welded polymer material. In ultrasonic welding of various plastic materials, the kinetic characteristic reflects the physical condition of the polymer in the weld joint zone, and can be used for quality control of the welded joints. The aforementioned properties of the kinetic characteristic determine the application of the in-process control as two options: manual and automatic. The in-process control of the polymer ultrasonic welding consistently guarantees high quality of the welded joints while allowing for possible irregularities in the polymer material as well as the operation of the ultrasonic generator.

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