Process Date: March 2000

This thin plastic was lap-welded with an Evolution 200 laser at a speed of 3600" per minute.

Laser welding of plastics is an application whose feasibility is very case specific, depending largely on material type and thickness. Due to the numerous material combinations and layering of different thicknesses, it is an application that  CO2 lasers address with mixed results. The thickness consideration relates to the fact that the CO2 laser wavelength does not penetrate most plastics without causing a loss of material. Therefore, penetration welding of plastics is not possible, as the material at the joint line is effectively vaporized!

However, a potential area of success is the lap welding of thin polyolefins ( polypropylene, etc.). In this case, "thin" typically means ~0.015" and lower. The keys to achieving good results in this type of welding are the use of an appropriate level of beam defocusing, and applied pressure at the joint interface. Trying to weld plastic with a focused gaussian beam generally results in cutting, or loss of material through vaporization. Diffusing the beam slightly allows the thin plastic time to heat up, but not degrade. The application of pressure ensures good contact between the two layers at the joint interface. In addition, a slight cooling period may be required to allow the bond to fully form.