Tube Welding Fixture

• I built and tested a small-scale plastic welding tool, to qualify its use in TPE tube welding.

To move away from relying on barbs or compression fittings as the transition from a plastic manifold to soft TPE tubing, I was tasked with building a prototype welding fixture to try to weld the soft tubing directly onto a hard plastic insert.

I mocked the fixture up with a couple air cylinders, cartridge heaters, 8020, and custom press heads that I designed to contour to the tubing and minimize mechanical deformation. The resulting welds were a success, both decently strong and watertight. After optimizing the variables as much as we could, we reached the limits of the test setup and development of the process was continued on-site at the manufacturer.

The pressure of the press heads was controlled by a needle valve going into both air cylinders, and the temperature of the weld surface was controlled with a PID controller reading a thermistor affixed to the outside of the press head and outputting to the cartridge heaters.