Joint strength for laser transmission welding of thermoplastics: A simulation approach

For laser transmission welding of thermoplastics the tensile strength of the joint is measured and microtome cuts of the joint are taken. The joining experiments are carried out for PA66 (Ultramid A3K) for different scan velocities and laser powers. Varying the laser power the tensile strength of the joint obtains a maximum. The value of the power where the maximum is reached depends on the scan velocity. In the thermal simulation the temperature distribution is calculated. The distributions perpendicular to the scan direction are compared to the microtome cuts of the joint. The temperature distribution in a plain parallel to the joining zone is used to calculate an area where the temperature is above the melting temperature and below the degradation temperature. Calculating this area as a function of the laser power gives a maximum area approximately at the same power where the tensile strength of the joint is maximal.