World first: injection compression molding on stack molds

  • Injection compression molding lowers unit costs, up to 20% material savings
  • Competitive process: injection times of 100ms
  • Synchronicity of 99.98 % between mold, machine and automation system

Netstal presents a world first at Fakuma 2015: injection compression molding on a stack mold. This new development will be demonstrated using a 425g (15oz) margarine tub made from PP which is manufactured with 4+4 cavities on an ELION 2800-2000 and weighs only 10.7g.

Following close collaboration between the mold manufacturer Plastisud, automation specialist Machines Pagès and Swiss injection molding manufacturer Netstal, the injection compression molding process and the stack mold technology were brought under the same roof. A slightly modified injection molding machine from the Netstal Elion Hybrid series is able to mold margarine tubs in standard format 15oz (425 grams) with IML decoration in a cycle time of five seconds. The process is performed in a stack mold with 4+4 cavities.

“The really revolutionary thing about the whole process is hidden from view: the polypropylene packaging is not injection molded but manufactured in an injection compression molding process,” explains Markus Dal Pian, Vice President, Sales & Marketing at Netstal.

injection compression mold

The challenge was to combine the injection compression molding process with the technology of a 4+4 cavity stack mold (source: Netstal)

Competitive process: injection times of 100ms

The combination of injection compression molding and stack mold can be considered as a novelty in the industrial production of packaging. The cavities are partially filled in only 100ms with extremely even results and the process is performed at a low pressure to prevent tension in the material. There is a significant increase in productivity through the use of a stack mold and reduction in material costs by up to 20% as well as high flexibility in terms of shape, appearance and decoration of the manufactured part, according to Netstal.

The high quality of the platen parallelism guarantees a synchronicity of 99.98 % between the mold, machine and automation system.

Injection compression molding lowers unit costs

The advantages of injection compression molding include narrow wall thicknesses and a lighter product resulting in lower unit costs. In addition, the end product (lids in particular) shows fewer signs of distortion and higher dimensional accuracy due to the lower stresses placed on the material. These properties make the end product more attractive for packers such as margarine manufacturers compared to other processes.

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