AUTOMOTIVE | SURFACES
Right: Pillar cap is produced using new Clearmelt process variant
company Rosti. Engel executives note that scratch resistance of certain exterior parts is a major issue for car makers, due to parts losing their lustre progressively as cars go through successive car washes. Testing has shown the initial sample parts to be very robust in this regard, says the company. Graeme Herlihy, Manag-
ing Director of Engel UK, says deep piano black parts like the one produced at Fakuma are often co-moulded in polycarbonate or PC/ABS with a PMMA surface (and also more recently in SAN). Legacy technology involved spraying ABS with PUR, but scrap levels can be quite high. These operations are also ideally carried out in cleanrooms, adding to costs. Costs of the new process should be similar to 2K moulding. The PUR layer is around 0.6 mm thick, versus around 2.2 mm in PMMA, so parts are lighter. The Clearmelt process was first demonstrated at
Fakuma 2015. In the original version, thermoplastic moulded parts can be combined with decor film or veneer elements using in-mould labelling (IML) and then the front surface is over-moulded with a transparent PUR. The latest version, called Colourline with Multi-Connect technology, makes it possible to add colour to the PUR. Modular equipment makes it possible to quickly and easily switch colours without any purging between one colour and the next; changeover time is around 15 minutes. A parking station holds up to seven colour modules. At Fakuma, Arburg showed another way to get bright and shiny auto parts. It demonstrated production of a two-component steering wheel
cover. This was done on a hydraulic two-component
Allrounder 470 S with a clamping force of 1,100 kN and two 170 injection units.
Polycarbonate provides strength, while an area made from PC/ABS can be selectively galvanised downstream. A special feature was the 100% quality control of each
An Arburg turnkey system at Fakuma produced steering wheel covers from PC and PC/ABS, which can be selectively galvanised in a down- stream operation. The quality inspection for the moulded parts takes place directly in the mould, and pictures showed up as the parts left the injection machine on a conveyor
46 INJECTION WORLD | November/December 2017
finished part with the aid of a thermal imaging camera integrated directly in the mould. This has the extra advantage of eliminating a separate test station to provide for a small installation area. Producers of thermoplastics meanwhile are developing ways to get high-gloss parts straight out of the mould, without the need for any co-moulding and downstream processes. One of these produc- ers is BASF with its new Deep Gloss, a 100% polyamide alloy that processes like a PA6 but which produces parts with very shiny surfaces and high abrasion resistance. The company said it combines the chemical resistance of semi-crystalline polymers with the high gloss and depth of view typical of amorphous materials. The company is aiming the product at, among other things, interior automotive parts currently produced in painted ABS. Xaver Hopfenspirger, Group Leader, Technical Development in the company’s Performance Materials Europe Transportation section, said at Fakuma that there are limits on abrasion resistance with such painted parts, and that ABS parts with a single paint layer have significantly lower quality than unpainted parts in Deep Gloss. No paint means no likelihood of orange peel effects, for example, and scrap levels are also lower. Deep Gloss is not a drop-in substitute for ABS however, since differences in shrinkage mean that new injection moulds are required. Hopfenspirger also admits that Deep Gloss cannot compete in quality terms with parts decorated with, for example, UV-crosslinked coatings, but its costs are lower. Just in time for Fakuma, BASF had produced demonstrators to show the high surface quality possible with Deep Gloss on difference surface structures, and to show that weld lines are virtually (totally, to this observer) invisible, even without the need for special mould conditioning systems like Variotherm. Good flow properties mean that the melt copies the tool surface very well, says Hopfen- spirger. “You just need to follow good design and processing rules,” he says. Some customers are already trialling the
product, which should go into full commercial production in late 2018. It is initially available only
www.injectionworld.com
PHOTO: PETER MAPLESTON
PHOTO: ENGEL
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