MOULD MAKING PETplanet Insider Vol. 23 No. 06/22 www.petpla.net 16 Schematic diagram of preform neck finish temperature for conventionally machined neck ring parts Application on beverage closure mould: At the beginning of 2021, a GDXL customer reported that a set of their existing injection moulds had some quality issues. It was being used for the production of wide-mouth bottle closures with an outer diameter of 116mm and a handle. The closures had ovality out of specification and were thus unable to tightly seal with the bottle finish. GDXL’s analysis found that the issue was due to a small, movable, inclined top part in the mould. Its cavity parts could be machined on the outer side of the cylindrical area with only one ring of annular water grooves by conventional means. There was no cooling water channel in the large metal area in the centre, which led to insufficient cooling of the closure. This resulted in large shrinkage and deformation of the closure after demoulding, which eventually caused ovalisation and poor sealing. GDXL proposed 3D printing to process two mould cavity parts with conformal water channels, for trial. The mould cavity parts with conformal water channel were found to be able to reduce demoulding temperature by about 10 °C; ovality was reduced by more than 50%, making it able to properly seal the bottle. GDXL will continue to develop different applications of 3D printing technology in beverage mould manufacturing and will continue to establish the relevant intellectual property registrations. The company hopes that, through the above sharing, it will inspire additional new and valuable applications of additive manufacturing technology and promote a deeper integration of it in mould manufacturing. GDXL Precise Machinery Co., Ltd. (GDXL), which was founded in 1993, has been focused on the food and beverage packaging industry for nearly 30 years. The company has experience in design, application, engineering and manufacturing technology of moulds for preforms, bottle blowing and bottle closures. GDXL provides food and beverage mould products and related engineering services. www.gdxl.com Schematic diagram of preform neck finish temperature with 3D printing conformal water channel Application on bottle blow mould: Carbonated beverage (CSD) bottles need to withstand high internal CO2 pressure and the base needs to resist stress cracking and base-roll-out. Improving the cooling rate and cooling uniformity during the blowing process can improve stress distribution, thereby enhancing the ability of the base to resist stress cracking and base-rollout. A faster cooling speed also helps to shorten the blowing cycle and thus improve production efficiency. GDXL applied 3D printing to process the base mould of carbonated bottles with conformal cooling channels. The new base mould was then replaced on the bottle mould for blowing and filling testing. Results indicated that the blown carbonated bottle had improved resistance to stress cracking and base-roll-out. Schematic diagram of the structure of the carbonated bottle base mould with 3D printing conformal water channel Cavity design for conventional machining (the water channel is a ring of water grooves on the outer cylindrical area) Cavity design for 3D printing integral machining
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