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In a classic workflow, the material sample is

granulated in the laboratory extruder and then sent to the injection moulder, who then produces samples. The SpeciMold creates injection-moulded specimens for common laboratory tests directly from the polymer sample destined for granulation, so directly from the extruded compound flow. SpeciMold fits between the compounding

Above: Brabender’s SpeciMold system automates production of laboratory sam- ples direct from the

compounder output

laboratory twin-screw extruder, which had 25mm screws. The well-known UltraGlide feature allows the filled screws and the drive block to be removed backwards from the stationary processing section.

Testing the limits Brabender introduced its SpeciMold just over a year ago. As the name suggests, this is an injection moulding machine for producing test plaques in-line with a laboratory compounding unit, which need not necessarily be a Brabender model. Michael Kunde, product manager for SpeciMold, says the unit enables quick, energy-saving produc- tion of samples and can help compound designers, additive manufacturers and plastics development laboratories accelerate the development of compound formulations. At the same time, it is said to help determine actual material properties that are closer to real-world conditions. The system was developed by Brabender together with UMSICHT, the Fraunhofer Institute for Environmental, Safety and Energy Technology. “It fits seamlessly into existing laboratory systems and solves various compound development challenges in one fell swoop, especially regarding residual moisture problems or dealing effectively with small material quantities,” Kunde says. It is critical for the success of the injection moulding handling process that the results from the laboratory testing are monitored and under- stood with careful detail, according to Kunde. This will prevent misinterpretations of the data sheet and avoid out-of-spec products. “Hence, for example, the addition of liquid or solid formula components in the laboratory extruder should be as close to real-world applications as possible. Special attention must be paid to the injection moulding process with all its parameters – the most important being, for example, control temperature/ temperature profile and forming pressure,” he says.

28 COMPOUNDING WORLD | December 2017

extruder and the die head or the laboratory unit’s downstream equipment. The unit is divided into a SpeciMold block, with piston and die head, together with a mould clamping section. The block divides the polymer flow into two parts: the main flow continues through a die head for further handling downstream line, while the bypass flow is diverted to a shooting pot. Once this is full, the still-molten molten compound is injected into the mould, forming a sample. The operator can therefore draw valid conclu- sions as to whether the material possesses the properties requested by the customer in a timelier manner than was previously the case. “After some comparative measurements against the conventional process, we could observe that the characteristics of the material processed with the SpeciMold are slightly closer to the reference values of the material data sheet,” says Kunde. “Obviously this is based on the fact that the material is only melted once while in the conventional process the material is melted more than once. However, the main advantage of the SpeciMold compared with the conventional process is the time advantage.” Process management of the SpeciMold is similar

to that used in real-world conditions – the mould- ing cycle involves a holding pressure phase, decompression and cooling phase – and the whole injection process is precisely documented. One useful feature is that the mould can be changed quickly, without the extruder having to be stopped. Even though SpeciMold has been tailored for optimum results with proven Brabender laboratory equipment for material developers, and is offered as an entire package with granulator, extruder and downstream equipment, Kunde says it can also be easily adapted for use with other suppliers’ laboratory systems and units.



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