Laser welding is a cost-effective process for assembling plastic auto parts.
Today, laser welding is fact, not fiction. Recent developments in high-power laser diode technology make it a cost-effective method for joining polymers and thermoplastics. Changing market conditions and more affordable welding equipment are prompting manufacturers to consider the advantages of joining plastic parts with light beams.
Although laser welding has been in experimental use for the last 10 years, many manufacturing engineers are still not familiar with this technology. It is relatively new compared to traditional joining techniques, such as ultrasonic, linear and orbital vibration, spin, stir, electromagnetic, hot-plate and extrusion welding, but it offers numerous advantages.
For instance, in laser welding, the energy input is highly localized, which creates less thermal and residual stresses than traditional welding techniques, resulting in a high quality weld. Lasers deliver high values of irradiance to selected areas on a plastic part; no other welding process can deliver as much energy in as small a location. This can produce rapid heating in a very small region. The localized nature of the heating and formation of the melt-pool makes lasers ideal for many plastic welding applications.
Laser welding is an economical alternative for joining many different types of thermoplastics. Today’s high-power diode lasers are also compact and reliable. They offer high efficiency—30 percent to 60 percent—with power up to 3 kilowatts. These systems also have low maintenance expenses.
Laser welding technology is ideal for rigid injection-molded thermoplastics, such as polyamides. It compares favorably to the most common plastic joining methods, such as friction, hot-tool and electromagnetic welding. As a result, laser welding is becoming an increasingly popular technique for assembling plastic auto parts, such as air intake manifolds and tailight assemblies.
Plastic parts can be joined with either noncontact laser welding or through-transmission laser welding. Both methods have pros and cons related to heat generation, plastic composition, joint stiffness, part design, joint thickness and color.