OPEN HOUSE | NEWS
Another, and perhaps
more immediate, trend is to lightweighting. It is being driven largely, but not exclu- sively, by the automotive industry and several of the many process demonstra- tions addressed it. For example, Arburg offers its propri- etary Profoam physical foaming system as an alterna- tive to the established Trexel Mucell technol- ogy (which it also offers to customers). It demonstrated it on a hybrid Allrounder 630H machine producing a backup battery cover weighing 80g on a two- cavity mould in a 30% glass reinforced PP on a 28s cycle. A weight saving of near 10% was achieved. The Profoam system
differs from the Mucell technique in that gas is introduced into a special pressurised hopper before it enters the screw, where it is dissolved into the polymer during plasticis- ing. This means that a relatively standard – and therefore lower cost – plas- ticising system can be
Below: An automotive head restraint carrier injection moulded using Fibre Direct Compounding LFT technology, which allows processors to adjust glass content and length at the machine
Left: This battery cover was moulded in 30% glass PP using Arburg’s Profoam physical foaming technology to reduce part weight
used. Arburg says that Profoam
plasticising is also more gentle than the Mucell system (which introduces gas into a modified plasticising unit) so it is highly effective with materials such as LFTs that are susceptible to shear damage. Mucell technol- ogy does allow higher levels of gas to be intro- duced, however.
Direct LFT Arburg’s Fibre Direct Compounding (FDC) technology for production of LFT parts was also demonstrated. Running on a hydraulic Allrounder 820s, it was producing an automo- tive headrest structure on a
36s cycle in a PP copolymer with 30% by weight of 12mm glass. The technol- ogy takes continuous glass rovings, then chops them on the machine and introduces them directly into the plasticising system. The company claims lower levels of fibre breakage during processing along with reduced raw material cost and improved flexibility (the moulder can adjust both glass content and fibre length as required). “The cut is adjustable up to 50mm but is running at 12mm on this project,” said Gaub. “Of course, they don’t stay that length but the average fibre length is relatively high.” He said the FDC technology is attracting
considerable interest from the automotive industry. The company also demonstrated how these lightweight technologies could be combined with a high quality part finish. A demonstration mould from Wirth of Germany with multiple surface finishes, including high gloss, was running a dynamic mould temperature (variotherm) process developed by E Braun together with Mucell physical foaming on a hydraulic Allrounder 520s machine. Cycle time was 55s. The PC-ABS blend material showed none of the surface swirling usually found with physical foaming on the 100g part. �
www.arburg.com
Clear advantage in 3D print
Arburg continues to develop its Freeformer additive manufacturing platform, with the latest extension to the range of validated materials a PMMA resin. Production was being demonstrated publicly for the first time during the open house event. Unlike with injection moulding, the transparent qualities are not achieved direct
from the build platform but require polishing back to the dense core. “What we wanted to show is that we can produce high density parts,” said Arburg Managing Director of Technology Heinz Gaub. “That is not to say we can produce optical parts but with the Freeformer process we can reach high mechanical strength.” Gaub said Arburg is completely committed to its additive manufacturing
Arburg can now 3D print PMMA
www.injectionworld.com
strategy for plastics, which it sees as complementary to injection moulding. “Look at metal and how many techniques are used to process it,” he said. “The same applies to plastics and the same for additive manufacturing. There will always be different processes because each solves a particular problem.”
July/August 2018 | INJECTION WORLD 15
PHOTO: AMI
PHOTO: AMI
PHOTO: AMI
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