K2016: Composite Tablet Housings Are A Technical Tour de Force

One of the interesting technologies at K2016 will be all-new, single-process composite lightweight housings for consumer electronics devices, such as tablets or smartphones. The goal is to significantly reduce weight compared to magnesium while providing stiffness and strength at low cost.

A new manufacturing process developed by three companies will be demonstrated live for the first time at Engel’s stand at K2016 in Düsseldorf, Germany.

The cell will run new technology developed by Leonhard Kurz Stiftung & Co. and Bond-Laminates, a wholly owned subsidiary of Lanxess. Andy Dentel, project manager at Bond-Laminates explains: “We start with a semi-finished thermoplastic composite with the trade name Tepex dynalite. This is formed by closing an injection mold, back-injected, and decorated inline using an in-mold decoration integration process specially developed for this purpose, an advancement over Kurz’s existing in-mold process. It involves the use of a transfer coating system.”

Housings ae 0.6 mm thin. (Engel)

Housings ae 0.6 mm thin. (Engel)

Housings with extremely thin walls for laptops and other devices are produced in a single processing step. The demo product has a wall thickness of just 0.6 millimeters

Engel engineered a highly automated manufacturing cell for the new material combination that can be scaled to mass production. “We see enormous potential in this area,” says Stefan Engleder, chief technical officer at Engel.

The cell was specifically designed for the combination of continuous fiber reinforced thermoplastic preforms and IMD films. Three technologies are combined: Engel “organomelt” for shaping and functionalizing thermoplastic fabrics, variomelt for optimizing the surface quality, and IMD. Extensive post-finishing is normally required for composite parts. The workhorse of the cell is an insert 500V/130 single injection molding machine with a roll-to-roll IMD unit, a six-axis robot, which handles the semi-finished and finished parts, and an infrared oven which was also developed and built by Engel for preheating the thermoplastic fabrics.

The Tepex dynalite material is reinforced with continuous glass and carbon fibers, embedded free of air inclusions in a polycarbonate matrix. “The advantage of our composite material is its very high strength and stiffness, combined with good toughness. These properties are what enable us to reduce the wall thickness so much, without compromising on the mechanical performance of the decorated components,” says Dentel.

Because the component is coated directly in the injection molding process, using a dry coating technology developed by Kurz, an additional coating process step can be eliminated. The result is substantial savings on costs, logistics, energy consumption and resources. “You don’t have to invest in a coating line, and you don’t have to separately store, transport, clean or pre-treat the injection-molded parts prior to coating. In other words, all the many processing steps required to coat composite components can be eliminated, since they are now integrated into the in-mold decoration process. In addition, you don’t have any coating waste due to overspray,” Dentel continues.

Integrating functions via the injection molding process reduces costs even further. For example, the demo part has an integrally molded frame around the edges made of a flame-retardant polycarbonate reinforced with 50 percent short glass fibers. Snap connections and screw bosses are also integrated into the part

About Doug Smock

Former Chief Editor at Plastics World and Senior Technical Editor Design News
Automation/Robotics, Carbon Composites, Electronics, Europe, In-mold labeling (IML), Injection Molding, Insert Molding, Polycarbonate, Reinforcing Material , , , , ,

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