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technology | In-line compounding Right: An automotive

pedal produced in PA6 LFT

using Arburg’s FDC technology

and MGS Mfg Group developed portable Pushtrusion units that PlastiComp said could easily connect to an installed injection machine for added versatility of an existing asset. However, PlastiComp recently said it is no longer actively marketing Pushtrusion, since injection moulding machine makers had developed their own systems. Engel did, in fact, introduce another system in

collaboration with Leistritz in 2007 but that project too has been terminated. That was billed as a two-colour injection- moulding compounder, combining an Engel duo machine with a Leistritz ZSE MAXX compounding extruder mounted to the side to allow a second injection unit to be mounted on top. This meant that, if required, the injection moulding machine could also be operated independently of the extruder for standard injection moulding production. Engel envisaged areas of application mainly in the automobile industry, but also in the areas of packing (pallets, boxes) and in processing natural fibres. Engel declined to comment on the project, but

sources say that while the idea behind the cooperation with Leistritz was to provide capacities for producing even small amounts of individual materials tailor-made for very specific applications, there were simply too few processors in need of the technology to make it worthwhile continuing the development.

Below: Fibre feeding unit on Arburg’s Fibre Direct Com- pounding (FDC) process

Certification issues One reason why plastics processing companies may hesitate to go down the in-line route and produce their own material mixtures is the topic of certification. “They have to guarantee that the material used has reproduc- ible properties,” says one close observer. “This can be a real challenge, particularly if the material knowledge

does not belong to the company’s core competencies.” LFT users opting for in-line LFT

compounding and part production can use either injection moulding or compression moulding. Although numbers are not available, it is probable that most in-line

compounding of LFTs involves compression moulding, using technology developed by

Dieffenbacher in partnership with Fraunhofer ICT. “The D-LFT process from Dieffenbacher is a

competing technology,” KraussMaffei’s Fenske says, but he adds that IMC technology has advantages when it comes to subsequent part finishing. In injection moulding, no manual trimming after the production process is necessary, he points out. This is not always the case with with D-LFT.

Direct options Today, Arburg has its own take on direct production and moulding of LFTs with its Fibre Direct Compounding (FDC) process. Strictly speaking, this is not in-line compounding and moulding since there is no separate compounding unit: glass fibres measuring up to 50mm long are fed directly into the liquid melt by means of a side feeder on the injection unit. The fibre length, fibre content and material combination can be individually adjusted. The process was developed together with the SKZ plastics technology institute in southern Germany. Mitsubishi Heavy Industries (MHI) Plastic Technol- ogy, which is in the process of merging with Ube Machinery, has also announced a system for direct feeding of fibres into the injection moulding machine. It describes its D-LFT System as “a kneading/injection moulding machine capable of forming high-strength LFT products from glass fibres and polypropylene (PP) resin, all in one process.” The company says the equipment incorporates a “unique screw shape, glass fibre feed method and other proprietary innovations [to] eliminate the need for kneaded pellets,” but does not go into more detail. MHI outlines “proprietary innovations in software, including technology that controls the glass fibre feed according to the amount of melted resin and a new control system that disperses the glass fibers into the melted resin with outstanding uniformity.” And the company says user support will be enhanced through the introduction of a new service whereby users will be provided with material mixing recipes for use with glass fibres manufactured by Nippon Electric Glass, which cooperated in developing the D-LFT System. The company began worldwide marketing of the D-LFT system in March 2015 and has offered the

40 INJECTION WORLD | September 2016

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