Calorimetric measurements of energy transfer efficiency and melting efficiency in CO2 laser beam welding
Abstract
The previous calorimetric studies of weld melting efficiency and arc efficiency in the GTAW and PAW processes have naturally led us to speculate as to the magnitude of the efficiencies in the LBW process which to data have also not been adequately investigated. Most welding engineers that have had experience with the LBW process are acutely aware that the metals' absorptivity, the surface finish, and the laser wavelength, all play an important role in affecting the energy transfer efficiency, but the extent of their influence and our understanding of the influence of other process variables is not well understood. In addition, it is widely thought that only the LBW or EBW processes can be selected for applications where thermal damage and distortion from the welding process must be kept to a minimum. For these reasons, we have looked forward to performing these calorimetric experiments since they potentially can answer such important questions as: whether or not the melting efficiency of the LBW process is superior to that obtainable with conventional GTAW and PAW welding processes. This study was prompted by poor production yields on switching device due to cracking of the ceramic header after final closure welding with the CO2 LBW process. This calorimetric study was begun in hopes of determining if allowed variations in production process control variables were responsible for increases in heat input and the resulting thermal stresses. By measuring the net heat input to the workpiece with the calorimeter and by measuring the laser output energy and the weld fusion zone size it was possible to determine the magnitudes of both the energy transfer efficiency and the melting efficiency as well as observe their dependence on the process variables.
- Publication:
-
Presented at the JOWOG 22D Joining Subgroup Meeting
- Pub Date:
- 1990
- Bibcode:
- 1990jowo.meet...23F
- Keywords:
-
- Calorimeters;
- Carbon Dioxide Lasers;
- Carbon Monoxide Lasers;
- Energy Transfer;
- Laser Welding;
- Melting;
- Focusing;
- Gas Lasers;
- Heat Measurement;
- Temperature Effects;
- Lasers and Masers