Diode laser transmission welding is a relatively new type of joining process for polymeric materials. A laser beam in the near infra red region of the spectrum will pass through thermoplastics yet will be absorbed by additives in the material such as pigments, bulk fillers and strengthening media. This work has used a high power direct diode laser to demonstrate the feasibility of joining nylon reinforced with up to 30% glass fibre. The effect of glass reinforcement on transmission has been investigated, as has the effect of processing speed on weld strength. Results indicate that although transmission is significantly reduced by the presence of glass fibre, it is possible to transmit sufficient energy, without causing damage to the transmitting layer, such that uncoloured reinforced nylon can be bonded to an absorbing lower layer; in this case a 30% glass reinforced nylon coloured with 1% carbon black.
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