Processing | composites
ogy to compound an LFT during the moulding process. The production system also incorporated an inline fl exural testing system for quality control. In Arburg’s long-fi bre direct injection moulding
process fi bres of up to 50mm can be added into the melt through a side feeder on the injection unit. The company says this minimises fi bre damage during material preparation. The fi bres come from rovings and are cut to the correct length in an upstream process. The process can be used to produce LFT components or to overmould a thermoplastic composite sheet. The 335g automotive pedal produced at Fakuma was
manufactured from PA6 from Akro Plastic on a cycle time of 50 seconds. A Multilift Select robotic system was used to remove the part, set it down and pass it on for inspection. During the quality check, the parts were bent in a defi ned manner at a fl exural testing station. If the resulting bend line was within tolerance, the parts were passed and placed on a conveyor. PlastiComp has developed a set of hybrid thermo-
plastic composites that combine long glass fi bre and long carbon fi bre reinforcement together in the same pellet for injection moulding. The US company says the new products expand the performance range of the long fi bre material options available to product designers while offering a cost effective route to adopt the high performance capabilities of carbon fi bre. “Carbon fi bre signifi cantly boosts strength and
stiffness, while glass fi bre allows the toughness that many choose long fi bre thermoplastic materials for to be retained. Strength and toughness are key long fi bre attributes that can’t be achieved in unison with other reinforcement methods,” says Eric Wollan, business development manager at PlastiComp. “Typically, carbon fi bre reinforced composites have a
price point that is up to fi ve times the cost of glass fi bre materials, which is a high entry barrier for many cost sensitive applications. Our long glass and carbon fi bre products can lower this entry point for adopting long carbon fi bre by up to 50%. In addition, blending these two reinforcements provides a unique set of properties that combines the best capabilities that each can offer individually,” he says. For example, PlastiComp claims that a polyamide 6/6 hybrid 40% long glass and carbon fi bre reinforced compos- ite with 20% carbon fi bre has a tensile strength of 284 MPa
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(41,200 psi), which is 96% that of an equivalently loaded long carbon fi bre material and 24% higher than a similar long glass fi bre material.
“There is an interesting synergy taking place in these hybrid long glass and carbon fi bre composites,” says Wollan. “We can cut the amount of
carbon fi bre used in half and still
keep 85-95% of the
strength and stiffness, plus the addition of glass fi bre is bumping up the durability by up to 25%. The performance combination really makes these products attractive, because they land right where a lot of people need to be to use long fi bre thermoplastic composites as substitutes for metals.”
PlastiComp has also introduced Velocity high fl ow
polyamide long fi bre reinforced composites. The company says that the products simplify the injection moulding of high fi bre content long fi bre thermoplastic (LFT) components by more easily producing the smooth, fi bre-free fi nish desired on external surfaces. Standard LFT materials with fi bre loadings of 50% or more typically exhibit high viscosity characteristics which can make them problematic to mould, particu- larly in thin wall sections. The company says that with standard high fi bre
content materials, higher moulding temperatures are required to obtain a resin-rich surface, which results in slower cycle times and increased operating costs. It claims that by using Velocity long fi bre grades, en- hanced fi bre-free surfaces can be obtained at 17-22˚C lower processing temperatures. A smooth-to-the- touch, resin-rich surface free of fi bres makes colours more vibrant and is capable of holding fi ner embossed details. Secondary fi nishing operations are not required. RTP Company has expanded
its Very Long Fiber reinforced Polypropylene (PP VLF) range to include low emission products. Claimed to be ideal for injection moulding, RTP says that the PP VLF products satisfy OEM requirements to reduce VOC levels found in thermoplastic materials specifi ed for use in automotive interior applications. International legislation and automotive OEMs have identifi ed the need to reduce odour, fogging and total VOCs to improve air
Above: This hybrid-moulded Victrex
PAEK-based composite
aircraft bracket cuts weight by up to 60%
compared to
stainless steel and titanium
Left: Image showing the improvement in surface fi nish available from Plasticomp’s Velocity long fi bre com- pounds
January/February 2015 | INJECTION WORLD 23
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