The hottest laser technology expands the applicati

Laser technology expands the application space in plastic processing

in 1917, physicist Albert Einstein () who taught at the University of Berlin in Germany found that ordinary light sources can be enhanced in what he called inductive or nylon material, which is a kind of semi crystalline thermoplastic stimulated emission with high physical and mechanical properties. However, the discovery of the later Nobel Prize winner was only a theory for a long time. Half a century has passed before the first CO2 laser was brought to the market in 1968 and stimulated luminescence became a widely used tool

in the 1960s, Theodore Harold Maiman, an American, introduced the first working laser. He designed the term laser, which is still used today as an abbreviation of "light amplification by stimulated emission of radiation"

laser as a tool

laser has almost become indispensable in the plastic processing industry. In the metal industry, they were mainly used for cutting in the early stage, and often combined with water jet cutting, which is still popular today. However, increasingly, lasers are also used in plastic connections, although some limitations of relevant materials and welding methods must still be considered

laser is absolutely important in rapid prototyping (RP). They melt materials and are used to build models. If necessary, the prototype mold made by the laser beam can even be used for complete small-scale production. Lasers are used to print and mark plastic products, engrave printing rollers, and check the conformity of finished products with quality standards. Moreover, at the end of the process, the inspected products are transferred to the repository by an unmanned conveying system, which is naturally guided by the laser

lasers have also attacked other branches of the plastic industry, such as quality assurance and production control. The measurement system produced by elovis company in Karlsruhe, Germany, can bring high measurement accuracy to materials that are difficult to measure in other ways (Fig. 1). Using laser technology, the device can determine the speed and length of plastic. Through the application of laser beam, accurate measurement can be achieved without calibration and independent of the processed materials

Figure 1 measuring product size by laser technology

laser technology has also opened up unimaginable potential in the marking of plastic molded parts with different shapes and materials. Letters, numbers, enterprise logo or code can be printed on plastic parts, and the accuracy can reach within 0.001mm. In this way, various parts or packaged products can be identified and tracked in the internal logistics system. Rofin Sinar laser company of Germany claims to provide a wide range of writing and a complete set of marking systems. It believes that the main advantages of this method are high flexibility, no pressure, no contact, high speed and precision related to batch size

from ruby laser to diode laser

the remarkable success story of laser begins with Maiman's invention of ruby laser, a so-called solid-state laser. Next came gas lasers and later semiconductor and diode lasers (Figure 2). The core of each laser contains an active medium. This medium attracts energy, usually from the light energy of a device known as a pumping light source. The atoms of the active medium release this light energy with a coherent beam, which is a beam of light with the same wavelength and vibration type. Then light, as a laser beam applied in different forms, is reflected several times between the two lenses before emerging from the partially transparent lens

Figure 2 the latest diode laser

in CO2 lasers, which are still widely used today, the active laser medium is formed by emitting light in a mixture of helium, nitrogen and carbon. Nd:yag lasers, which are also widely used, are different. In some early solid-state lasers, the active medium consisted of neodymium doped crystals composed of chemical elements yttrium, aluminum and garnet (YAG). In the late 1980s, semiconductor technology finally introduced more and more durable and highly active diode lasers to the market. Due to the relatively low energy generated, diode lasers are very effective in CD and DVD drives and are also used to connect plastics by laser welding

although it is still in the early stage of the promising development path, the welding of plastic products through the concentrated laser beam has proved to be the best polymer connection method. One of the pioneers in this broad field is the German company jenoptek. The company took the lead in focusing on the research and development of laser welding technology, which has made this technology an alternative to thermal and mechanical connection processes, riveting and bonding to some extent. An important limitation is that at least one party must be able to easily absorb the laser of a specific wavelength when connecting. But this method has a lot of advantages: without contact and force, energy input is generated. Fragile and machine sensitive products can be easily welded. In the actual welding process, there is no friction and melt discharge at the weld

better beam quality

Leister, a Swiss plastic welding equipment manufacturer, predicts that there are two main trends in the field of laser welding. The trend of polymer material research is towards material modification and the development of special laser additives mixed with raw materials. In this way, the plastic can be connected with a laser beam with a higher degree of design freedom

on the other hand, process operators and equipment manufacturers are increasingly cooperating to optimize existing plastic connection methods. Laidan has developed the mask welding (MA light, efficient process, strong impact resistance, good dimensional stability under high and low temperature conditions, etc.) process, which is especially suitable for the medical field. The foil can be welded to the microplate without melt flowing into the gap. Masks are also generally used in Applied Fluid Science, especially in micro fluid components. This precise and cost-effective process has found application in more than 40 kinds of parts based on natural fiber composites used in entertainment electronic products and computer peripheral products in automobiles. Another process developed by laidan is radial welding. In this process, the parts with reasonable butt joint are welded together and do not have to move according to the laser. In medical technology, this process is used to weld catheter accessories. Radiation welding has also found applications in sensor technology, fluid science and automotive engineering. The patented Globo welding process of laidan has been applied in medical technology. It can make the joint parts press together strongly, for example, two transparent foils can be welded together. The heat energy is transferred to the foil through the absorbent black substrate. This concept can be applied to large-area component bonding (Figure 3)

Figure 3. Globo welding process used by laidan for three-dimensional laser welding of plastic products

German optotools believes that the reason why laser welding has not yet established a stronger position in the market is that the beam quality of the existing laser mode is still poor. The company strives to make up for this deficiency by using the latest generation of fiber connected diode lasers (Figure 4). Optotools' modular design and extremely high beam quality enable it to be installed in the so-called flow scanner. In this combination, the new module can give priority to the near synchronous connection process in laser welding. Thus, the increase in cycle rate has decisively increased the productivity of the equipment

this view has been confirmed by LPKF laser and electronics, whose plastic welding branch relies on optotool's laser mode. LPKF regards the advantages of this new connection method as a cost-effective and material saving alternative to ultrasonic welding and adhesive bonding. Laser welding is clean, the input energy is easy to be controlled, and the mechanical load on the components is light. Laser welding is particularly effective when processing sensitive materials, such as electronic parts or sensitive medical components, and significantly reduces the probability of waste generation. October 2011

Architecture and piercing

where else have lasers proved their ability in plastic processing? What other applications can the undisputed advantages of this technology conquer? An example is micro technology. The laser architecture of plastics has become mature as an alternative to traditional processes, especially when the impact on sensitive components must be reduced. With a new light source tailored for this process, the range of processing capacity can be promoted to the nanometer level

votan a machining center provided by jenotik company uses two ways of laser energy. This machine is used to pierce the designed rupture point of the passenger airbag on the car dashboard and form the boundary and contour of the whole component at the same time. Jenoptek emphasizes that the two laser modes integrated in the production center work independently. However, due to cost reasons, ordinary CO2 laser sources can also be used in smaller production operations

plastic processing enterprises can also use laser technology to clean the viscous residues on the mold, and pretreat the surface of various materials for printing or connection. The advantage of the laser process here is the non-contact local treatment of components, and the necessary operations can be integrated into the production process, and the operation is very eco-friendly. It is the combination of these factors that will enable lasers to continue their success story in the plastic processing industry and prove their indispensability