In the lead-up to K 2022, the German Mechanical Engineering Industry Association VDMA is publishing a series of interviews with leading businesspersons in the industry, under the title Way2K. Here, Volker Reichert, managing director at A & E Produktionstechnik GmbH talks about the impact of recyclate quality on moulded parts - even when used as a middle layer in sandwich components.
Dr. Reichert, can sandwich injection moulding, for which your company has developed a specific nozzle, contribute to the recovery of recycled plastics?
Sandwich injection moulding is one way of sensibly reprocessing recycled plastics. It is not a universal remedy however, since new plastic is also needed to produce new moulded parts, and these recycled plastics must be of an appropriate quality. The process always requires two melt streams consisting of different materials, so the higher investment and operating costs must also be taken into account in terms of economic viability.
So, practically speaking, you can't hide unsorted and poorly processed recyclates in the middle layer?
If high-quality parts are to be produced, high-quality recyclates must be processed. If you pay two or three-figure euro amounts per kilogram for high-quality engineered plastics, you can't put in recyclates that are perhaps only within the cent range. In principle, of course, it is possible to mechanically recycle plastics from the yellow bag. But the components made from them would hardly be able to meet the requirements placed on them. In terms of recycling, an attempt should be made to use the same materials for the outer layer and core. In this case, it can be assumed that the material properties are approximately the same. If sandwich parts are injection-moulded from different plastics, the problem will arise again later that they will have to be separated during recycling.
The sandwich process has been around for decades. Will it gain in importance as a result of the current trend towards increased usage of recycled materials?
The process has always had a niche existence. I do not think that its importance will increase exorbitantly as a result of the current discussion. The growth rates will probably not differ from those of recent years.
Nevertheless, the pressure to use recyclates is increasing.
Some of our customers, i.e. the injection moulders, do not want the buyers of the moulded parts to know that recycled material has been processed. At the moment however, we also notice that the key words "circular economy" and "resource conservation" also include recycled content. The problem is, however, that when injection moulders process recycled material, they assume responsibility for ensuring that the moulded parts with recycled material also meet the given specifications. In the case of high-quality parts, this leads to renewed testing and certification. These costs then will have to be recouped. The low price for recyclates alone – if it is lower at all – will not be sufficient in many cases.
