Plastics professionals

© Photo | KD Busch

Geiss AG is the first company worldwide to laser-cut thermoformed components. Two mega-trends are helping.

The Geiss AG, a mechanical engineering company in the northern Bavarian town of Sesslach, builds machines that cover the whole spectrum of thermoplastics, composites and polyolefins. The company is a pioneer in thermoforming — a rival to injection molding and similar in some respects to deep-drawing for sheet metal. The thermoforming process applies a vacuum to shape preheated thermoplastic sheets or films. Subsequently, the formed parts have to be removed from the sheet, which is usually rectangular in shape, once it has re-hardened. To help its customers carry out this work,

There is more

The Geiss AG in the northern Bavarian town of Sesslach builds machines that cover the whole spectrum of thermoplastics, composites and polyolefins. The company is a pioneer in thermoforming and also breaks new ground when it comes to cutting plastics: Geiss AG is the only company of its kind worldwide to use the laser as a tool to machine contours.

Geiss has offered CNC units to cut along curves since 1984. Milling and cutting techniques using ultrasound, hot and cold blades, and occasionally even water jets are the classic methods for machining curves. Manfred Geiss, owner of Geiss AG, was unique in recognizing the potentials of the laser. “We’d been using lasers to cut structural and stainless steel here in our sheet metal fabrication operations for years. So why not use lasers to cut plastics too?”

trumpf-laser-cut-maschine-geiss

Geiss Laser cutting machine for thermoformed parts. Have a look at the machine here. (galery)

As machine builders with a strong focus on plastics, numerous factors played a role in the company’s deliberations. Lasers are free of wear and, unlike water jet cutting, do not require the use of abrasives. They are flexible, fast, dry, and maintenance free. They achieve extreme precision at consis-tently high quality. All they require is a fume hood to extract the hydrocarbon vapors generated during the cutting process.

These plastics are suited for laser-cutting

Only PVCs and other halogenated plastics are beyond the range of laser cutting because of the hydrochlorides produced; they combine in the exhaust to form toxic dioxins. Manfred Geiss sums up: “ABS, acrylics, carbon fibers, PET, and polycarbonates are all suitable for laser processing. Fiberglass-reinforced plastics need more laser power. Laminates with a foam filling won’t work at all. And blades are more effective when cutting very thin materials.”

To supplement traditional methods, Geiss developed its own portable laser cutting machine, with TRUMPF’s assistance. The machine uses Cartesian coordinates and features a compact, built-in TruCoax CO2 laser generating 1,000 watts of power. All the optical components were supplied by TRUMPF, while the CNC machine itself is a one-of-a-kind Geiss design. Thanks to their elaborate parametrics, all the Geiss three-and five-axis CNC machines can be equipped with a laser cutting option.

Advantages of laser light

Specifically matched to processing plastics, the CO2 laser works with a wavelength of 9.3 microns instead of the usual 10.6 microns. This improves the absorption and thus cutting speed for many plastics by around ten percent. In addition, laser technology has many advantages over other tools.

The cutting tool never makes contact during laser processing, meaning that no drag forces are produced — a real virtue given current trends toward ever thinner materials. And, since simple part clamps are sufficient, there is also a cost benefit.“Lasers also reach contours and cutouts that are completely inaccessible to milling spindles,” Geiss adds. “Corners and cutouts with very small radii are also possible, as are hair-fine holes through composite materials.”

Manfred-Geiss-Sesslach

Manfred Geiss uses light to cut thermoformed components.

This obviates finishing work in many applications. When processing acrylics, for example, the cut edges look flame-polished. Laser cutting is also the method of choice when clean rooms must remain free of dust and chips. And finally, whereas traditional methods reach their physical limits with polyamide fibers — milling causes the fibers to fray andblades bunch up the material in front of them — lasers cut cleanly through the material without any fraying or bunching.

Feasibility tests

Using a demonstration machine installed on Geiss premises, the mechanical engineers conduct tests to determine whether a laser would be the most suitable tool for the customer’s purposes and to find out which parameters deliver the best cutting results. This is augmented by certified emissions tests by a leading inspection authority — TÜV Süd. As an example, the shell of a freshly manufactured suitcase consists of polycarbonate, one millimeter thick.

The length of the curved seam is 2,480 millimeters; 16 holes have to be drilled. At an advancing rate of 9,000 millimeters a minute and laser power of 500 watts, the cutting cycle lasts 69 seconds. The firm’s own sled design is made of ABS four millimeters thick, using PMMA (polymethyl methacrylate). The cutting length is 2,580 millimeters and there are two holes to be drilled. The laser completes the job in 49 seconds. Similarly, the laser cuts an air grille made of ABS and acrylic in just 260 seconds in the high-speed mode, even though the grille includes 168 rectangular cutouts, six holes, and a cutting length of 860 millimeters.

Composite-laser-cut

Whether for clean contours or hair-thin perforations: Lasers and composite materials are a perfect match.

Two mega-trends in manufacturing

Laser applications are many and varied and include plastics for headlamps, cladding, and floorings in cars, sun visors in trucks, and films for the furniture-making, construction and packaging industries. Geiss believes in the success of laser cutting. “Two mega-trends are driving its growing popularity. One is the shift toward lightness; vehicles today have weight-optimized designs with thinner walls, for instance. The other is the triumph of the composites. For materials such as glass- and carbon-fiber reinforced plastics, lasers are just the ticket.”

Contact:
Geiss AG, Manfred Geiss
Phone +49 9569 9221 – 51
e-mail: manfred.geiss@geiss-ttt.com

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