INNOVATION | JOINING AND ASSEMBLY
made of a laser-transparent plastic and the other of a laser-absorbing plastic. The chart below shows materials that can be laser welded. The technology finds many applications in medical engineering, for example, for joining housings for electronic components such as insulin devices or pacemak- ers. In addition, cylindrical components such as catheters or pins can be laser welded precisely and reliably, as well as cartridges and microfluidics for diagnostic procedures. Individual components of plastic valves that have to withstand high pressures can also be welded well and stably with a laser. Geometric possibilities are almost limitless. The joining of two transparent parts is also possible using special radiation sources. This is particularly of interest when certification provisions for the component do not permit the addition of a laser absorber or the component must be evaluated using optical analysis methods after welding. Recent developments at LPKF include a dual clamping device (DCD), which provides high process stability and short cycle times. Ensuring a uniform contact pressure during laser welding of plastic components is an important quality crite- rion. This is because the weld seam achieves optimum quality only at constant pressure across
Materials that can be laser welded
the entire welding area. In most systems, glass tools perform this task because of their laser transparency. LPKF says that the DCD offers many advantages over glass. It is an internal and external clamping system, made of metal. Due to its design with a channel for the laser beam and several specially shaped, fine holding bars that do not interfere with the weld, the DCD enables reliable, deformation-free welding seams. Even after many production cycles, consistently high-quality welding results are guaranteed, it says. The DCD can therefore overcome the disadvan-
tages of glass tools. Glass becomes blackened due to irradiation with the laser. Particles are bound to the material, which impair the ability of the laser beam to pass through the glass. As a result, the quality of the weld may suffer. To prevent this problem, the glass must be cleaned or replaced regularly, resulting in production interruptions. Handling is often cumbersome, and the glass can break during the cleaning process and must then be reordered and reinserted. This can affect a large production throughput.
LPKF has also developed a calibrated and certified
transmission measuring device for laser plastic welding. In laser plastic welding, the light transmis-
SOURCE: LPKF 38 INJECTION WORLD | May 2021
www.injectionworld.com
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