PETpla.net Insider 09 / 2021

MOULD MAKING PETplanet Insider Vol. 22 No. 09/21 www.petpla.net 24 A frugally designed mould generation Focus on core functions – reduce components MHT AG introduces a new frugal mould generation. The simplifications are in the first injec- tion moulding cycle: instead of the usual transfer to a removal unit that guides the preforms out of the mould after injection, a free fall is used. The frugal mould does without a complex post-cooling unit. Although this increases the cycle time, this fact is less important to users in niche areas, newcomers or producers in emerging regions. Some changes have been made inside the mould. The designers reduced the mould cavity to a small number of components by replacing the support ring with a much smaller retaining ring and dispensing with the conical ring. The simplification approach also offers room for change in the neck ring. This has now been designed without cooling. Test series confirm good cooling of the preform thread during production. If neces- sary, though, the cooling can still be upgraded at any time. That is the basic idea of the frugal principle: the tool grows with the increasing require- ments of the user. The frugal principle is applicable to a fixed mould cavity distance in small moulds with 24 or 32 mould cavities. The hot runner components come from the Legacy series, which is known for its space-saving use and robust design. Reduction without compromise To ensure the highest preform quality, frugally designed mould components are subject to the same requirements as components of a high-performance mould. MHT AG manufactures all components on the same equipment and subjects exter- nally sourced components to equally extensive quality monitoring. There are no differences, even in the choice of materials. This ensures the dimen- sional accuracy of the end product. By maintaining fine tolerances in the pro- duction of the shaping components, the strip line appears just as precise and fine in frugal tools from MHT as in high-performance tools. This strip line is often unclean and coarse in preform production using cheap tools from alternative suppliers. When demould- ing preforms, users of a frugal mould also expect the slides to run smoothly. The solution is to guide the slide frame over roller bearings. This reduces maintenance intervals and the wear on the mould components. Powerpack quality Two frugal moulds are already in the possession of one of MHT’s long-standing partners and custom- ers. Powerpack Quality approached MHT looking for a cost-effective offer comprising an injection mould that still manages to produce high-quality preforms. Powerpack Quality has been active in the PET bottle busi- ness since 2009. Two years later, the company started its preform produc- tion, primarily to supply customers in Thailand. Within just eleven years, the company succeeded in expanding its machine pool to 16 systems. Various 16- and 24-cavity moulds from MHT are used in these systems. In total, Powerpack processes 200-240 t of plastic per month, from a granulate to the bottle preform. When inquiring about new moulds, General Manager Amnart Wanasoontornkul focuses on three factors in particular: High mould accuracy, durability and pre- form quality. These are the absolute requirements that a cost-effective small mould is expected to meet. It was immediately clear that a “frugal engineering” project was needed. The shared motto was: “High quality at affordable prices.” After the first frugal mould was a complete success, Powerpack 2020 put another 24-cavity mould into operation. “The production of the preforms is distinguished by excel- lent quality. The concept was also F.l.t.r.: Mr Prawit Yodprechavigit (KraussMaffei Group SEA), Mr Amnart Wanaso- ontornkul (General Manager, Powerpack Quality), Mrs Mayuree Wanasoontornkul (Managing Director, Powerpack Quality)