thermoplastic composites | Innovation
Above: These lightweight computer cases are moulded with Covestro TPC materials
able with fabric-based materials, they say. Other components may see loadings in multiple directions. Studies on a number of beam-like hang-on components have shown that a typical weight-optimised laminate would have a combination of 0° and ±45° directional layers. “In such a case, UD material offers higher weight savings than traditional fabric-based materials, as the 90° orientations in a traditional 0/90° fabric simply add weight without any structural contribution,” according to the SABIC specialists. “For equal stiffness performance, the UD tape based solution would be 26% lighter.” Tapes are also central to DSM’s development effort in TPCs. It is set to unveil its latest product develop- ments in UD tape at the JEC World 2017 composites congress in Paris in March. “The strategy involves close collaboration with partners to integrate parts design, materials selection and manufacturing processes through iterative feedback loops between these different stages in the total development process,” the company says. DSM has developed expertise in UD tapes based on
its polyamide materials portfolio (which includes EcoPaXX PA 410, PA4T-based ForTii, and Akulon PA66) with carbon or glass fibre reinforcement. They are suitable, among other things, for use in injection moulded parts with localised reinforcement and have fibre contents varying from 50 to 65 wt%. Tape widths can be anything from 6mm to 600mm and are supplied through a toll partner using DSM intellectual property, process modeling, and specialty polyamides. “Polyamide-based UD tapes are capable of covering
a vast territory of engineering needs currently catered for by metals,” says Raj Mathur, DSM’s Global Manager Advanced Thermoplastic Composites. “There is not much advantage in storing UD tape on the shelf, as fibre content requirements vary with engineering specifica- tions and cost management needs. Our current
22 INJECTION WORLD | January/February 2017
‘standard’ portfolio is based on projects that we have already completed or are currently engaged in, but DSM is capable of producing a very wide range of variants.” Some production of TPCs is still in the hands of independents. At PlastiComp, CEO Eric Wollan says the company’s new range of tapes has generated a great deal of interest. He says since last year numerous companies have been sampling types based on high temperature polyamides, and also other ETPs, rein- forced with carbon or glass fibre for various applica- tions. Wollan highlights piping for oil and gas, and also says there is a lot of momentum in selective reinforce- ment in injection moulded parts. “At the moment, there’s a lot of ‘tyre kicking’ going on, but no clear commercial applications,” he says. He adds there is a general sentiment that prices need to come down, but that is difficult to achieve when volumes are low.
Electronic opportunity It’s not all about cars. Consumers want their mobile devices (TVs too) to be thinner and lighter, and all the while stronger and faster too, according to Covestro. On top of that, they want a cool design, and it should be good for the planet. “Metals and conventional compos- ites rapidly reach their limits when faced with such demands,” the company says. For this reason, it has developed what it calls “a completely new composite technology for the efficient manufacture of housings and other components” based on thermoplastics and continuous carbon fibres. According to David Hartmann, who heads the area of thermoplastic composites at Covestro together with Michael Schmidt, Covestro TPC solutions “provide the best strength-to-weight ratio of all standard composites on the market and also outperform metals in this respect.” They also offer a UL94 V-0 flammability rating. The composites are based on films of endless
unidirectional carbon fibres. Several layers of these films are positioned one on top of the other, cut and then laminated to produce extremely stiff and light- weight composite sheets with no distortion or shrink- age. The number, direction and sequence of layers can be optimised for each application. The blanks have an “organic” grain pattern, their high thermal conductivity makes them feel cool, and they sound like metals on impact. Covestro says it is investing in their further develop- ment. Besides research and the March 2015 acquisition of Thermoplast Composite - a German company specialising in composites – its current activities are focusing on gradually establishing a global production network and an expanded product portfolio. “We’re also working with machine manufacturers and carbon fibre
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