Thermoplastics can be welded with laser should one piece be transparent and the other absorptive to laser energy. During the welding process parts are clamped together so that laser energy can pass through the laser-transparent part and be absorbed by the laser-absorptive part. Due to intimate contact between two pieces, the laser-transparent part heats up through conduction and two plastics are fused together.

The bottom material is often laser-absorptive due to carbon black content; however there are other additives that can be used, thus opening possibilities to welding colored materials. Additionally a laser absorbent dye such as Clearweld by Gentex Corp. can be applied between two laser-transparent pieces, enabling them to be welded together.

Nearly all thermoplastics and thermoplastic elastomers can be welded/bonded with laser. There are also certain combinations of dissimilar materials that can be welded. For instance TPE and PBT, though one is soft and one is rigid, are compatible. For successful welding to occur two criteria need to be met; 1) the melting ranges of chosen materials have to be overlapping, and 2) the materials have to be to be chemically compatible. Naturally, most readily weldable combinations involve same materials. While it is difficult to tell with certainty whether or not a particular set of materials can be welded with laser, the chart below gives general overview of possible combinations.

If you have a particular combination we welcome the opportunity to offer complimentary material compatibility evaluation and feasibility testing it in our laser lab. Please feel free to contact us regarding your application.