cavity polishedIn February 2015, RPM commenced design of a custom stack mould tool for Tekplas Ltd.

Tekplas are a Hamilton based company that provide leading edge plastic engineering technology and services to a range of high end technical industries, such as human nutritional health, animal health, agricultural, dairy industry and industrial mouldings; both in New Zealand and abroad.

Tekplas Technical Director, Ian McDougal, says “We put RPM through their paces with this one! We had a lot of specific requests and we knew these guys would deliver. They are excellent tool makers and their team bring some extremely high level tooling design skills to the party.”

The client brief for the injection mould tooling design required a 127mm LLDPE reclosure lid. Working with LLDPE dictates multiple split lines for good venting due to narrow moulding parameters, and efficient cooling is essential to achieve part flatness. Material injection and part ejection both from the core side dictated a bespoke pneumatic stripper design.

The lid is a high volume part, which commanded a robust injection moulding tool design.

Design challenges also included an additional request for in-mould servicing, cavity insert changeability and robot access. In particular, a 200 mm opening was required for the robot take off for each stack. This meant the cavity inserts were kept to a minimal height and all services (air, water and power) had to be positioned discretely.

The stack mould tool was manufactured to RPM’s high volume 101 standard. Accuracy and precision along with quality materials are essential to the success of each project. The stand-alone round cavity stacks are fully interchangeable within the injection mould tool. With service connections through the plate transfer, changeovers can be done with minimum disruption to production.

The stack mould tool was commissioned on in late March, and on completion just 14 weeks later, was installed into a dedicated injection moulding machine with Cartesian robot take off and conveyor part handling at the Tekplas facility in Hamilton.

The moulding tool has now produced over 10 million parts and going great guns.


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