Extrusion International 4-2025-USA

47 Extrusion International 4/2025 solid core to alter the die gap at every wanted position over the circumference of the die. It is clear that only the cost to purchase the single parts and to assemble the PWDS system are much higher than the cost of a simple solid GWDS die and a profiled solid GWDS core. It is also clear that the GWDS solution does not require maintenance in regular intervals and that there exists no danger that the GWDS solution can fail and cause a machine stop. That is the reason why the GWDS solution stands head and shoulder above the PWDS solution. Attempts to establish the GWDS technology into the market Initial intensive attempts to convince German compa- nies which produce blowmolding machines, to take over the GWDS technology and to offer it to potential custom- ers failed. It is clear that it is possible to earn much more money by selling an extremely complex PWDS system than can be earned by selling simply a solid die and a solid core. Furthermore there exists a very close and long last- ing relationship between the company which offered the PWDS system and the machine producers. Additionally a further obstacle exists. It affords a certain experience and know-how to design and to profile GWDS dies and cores according to the needs of individual articles. So it would have been necessary to invest some affords to become acquainted with the new technology. The next attempt was to ask companies which produce blow molded articles wether they are interested to im- prove the quality of their products and in the same time to reduce the weight of the articles. But by doing this it was clear that the company produced the articlemostly since a long time. Using a conventional die the produced articles and the customers were content with the quality of the products. So why dismantling the existing die and spend money to buy a new die? This especially as there exists nearly no experience with the completely new innovative GWDS die solution which contradicts the knowledge that has been gathered over decades by several generations of engineers. In spite of this poor starting position some companies dared to retrofit their blow molding heads in their production machines with a GWDS die and a GWDS core. But for a long time no company could be found that decided to retrofit a head that had been equipped with a PWDS system. So GWDS dies were attached exclusively to heads which were not able to vary the wall thickness of the parison while it is discharged. The weight of the articles could be reduced by retrofit - ting the heads in nearly in all cases in a two figured per - cent range. Also the cycle time could be reduced signifi - cantly by avoiding thick wall regions in the articles. Those results were then presented to machine producers. But again no German machine producer could be convinced to offer the advantageous GWDS solution to the custom- ers. In the year 2024 for the first time the chance came up to retrofit a head that used a copy of a PWDS system with a solid GWDS die and core. As in the meantime since many years the patent protection for the PWDS system has lapsed several companies like the Italian S.B. Enter- prise Srl have copied the PWDS solution. Amachineproducerhadequippedhisheadwithacopy of a PWDS system. But he did not manage it to reduce the weight of the article in the intended amount. That is why he decided to dismantle the expensive “PWDS” system from the head and to attach instead a solid GWDS die and a solid GWDS core (right side of Fig. 4). As well the GWDS die as also the core was profiled ac - cording to the needs of the article which was to be pro- duced. The weight of the article could be reduced by 5 percent while still fulfilling all required implicational tests. Nevertheless no European machine producer could be found which decided to profit from the advan - tageous GWDS solution. May be this will change when in October the GWDS solution will be offered during the coming 2025 K-show hall 13/B77 in Düsseldorf. The Author Dr.–Ing. Heinz Groß Dr.-Ing. Heinz Groß Ringstr. 137, 64380 Roßdorf, Germany www.gross-k.de Picture 4: Comparison of an complex Italian 3DX system of S. B. Enterprise Srl which is nearly a 1/1 copy of a PWDS system on the left side, with a simple, solid GWDS die and core mounted on a head (right side) (Photo S.R. Enterprise Srl)