Lightweighting to the extreme

The XTREME machine allows the production of preforms of up to 10% lighter than the lightest injection-moulded preform. Developed by SIPA, this PET preform injection-compression moulding machine can remove more weight from the body and base and enable the development of new designs. The technology used allows a preform with a length-to-wall thickness ratio (L/t) of more than 50, which is said to be unheard of before XTREME was released. The machine has the ability to make a preform with an L/t ratio of 80.

Injection-compression moulding overcomes the issue of filling moulds with very thin walls by having the moulds slightly open when injection starts, and then closing them as dosing finishes. This means lower injection pressure can be used, lower clamp force is needed (which has the additional benefit of extending mould life), and there is less stress on the melt – which means acetaldehyde (AA) levels are reduced, and resin intrinsic viscosity (IV) falls less.

The machine can produce preforms with thinner bases. In a conventional preform, the thickness of the base has more to do with enabling the mould cavity to fill than it has with bottle performance, but XTREME injection-compression removes that limitation. As a result, it is now possible to make a preform for a 500-mL bottle that weighs just six grams. The system is well suited to production of preforms for bottles up to 1.5 L in volume, but can also be used for bottles up to 2.5 L.

Compared with other moulding equipment, the XTREME features a high productivity system, with the mould opening and closing working on a cam, so cycle time is just a fraction of what it is on an injection moulding machine.

Energy efficient,simple operation

The machine also uses lower temperatures and 10% less energy than an injection moulding system with the same output. It also uses up less space.A 72-cavity XTREME machine takes up just 34.5 m2, which is over 30m2 less than SIPA’s own XFORM – one of the most compact preform injection moulding machines on the market.

The mechanical layout of the XTREME has some similarities with a rotary stretch-blow moulding machine. It uses only pneumatic valves and pneumatic operation has a lower sensitivity to very short power interruptions and the overall quality of the electrical supply. This is a significant feature for food processors in developing countries. The machine has no hydraulics.

Time-saving features

Having lightweight mould blocks, the new system makes it easy for operators to change blocks. This design quality is ideal for companies that manufacture a wide range of products. According to SIPA, it only takes about 45 minutes to change all the mould blocks or stacks on a 72-cavity XTREME machine –about one-fourth of the time it takes to change a 72-cavity mould on a conventional injection moulding machine. Additionally, product changeover times are also significantly reduced. The machine allows the production of two different types of preform at the same time.

The machine is equipped with an automatic opto-electronic system, which allows “lights out” operations that run on minimal manual intervention.

The moulds are mounted in blocks of three on a high-speed carousel fed by an extruder. The extruder rotates continuously, delivering melt to the dosing devices mounted directly under the preform moulds, which are mounted vertically. There is no hot runner system in the conventional sense.

The preGifts for Runners