Process control

  • Laser Plastic Welding Pyrometercurve Laser Plastic Welding Pyrometercurve

Process monitoring during the laser welding of plastics can be divided into three areas:
  1. Upstream checking of the components
  2. Online checking of the welding process
  3. Downstream checking of the welded components 

Various monitoring, checking, or control methods can be used in each of these three areas. The issue of when a particular method can or should be utilized depends on the nature of the component and customer needs. In sectors such as the automobile industry or medical engineering, continuous process monitoring is frequently required. However, the best way to monitor a welding process can only be determined after carrying out an analysis and obtaining advice. The question of which monitoring methods are suitable at a particular time and location must be clarified on an individual basis. The figure shows a selection of possible methods.

  1. Upstream checking The component check covers all the requirements that the components must meet to ensure successful welding. The components are separated by the housing and cover prior to welding. Sensors or a camera system can be used to check how various components are positioned, both individually and in relation to one another. 
  2. Online checking of the welding process Depending on the configuration, the welding parameters of laser power, speed/time, clamping pressure/force, or even a melt path can be monitored during welding. Another option is to use pyrometry. In this case, a sensor detects the heat in the welding zone, which is then com-pared with a reference measurement. 
  3. In the case of certain applications, a camera can be used to gain a visual impression of the welding seam at the end of the welding process. With the help of digital color matching, this can then provide information about the quality of the welding seam.