Sunday 10 January 2021

Rule of Thumb for Polymer Engineering: The Polymer Product Pentagram


In this rule of thumb post, we discuss the Polymer Product Pentagram used as an overarching framework for injection moulded plastic products.

There are five factors, summarized as the Polymer Product Pentagram, which influence the outcome in having best in class injection moulded parts [1]:

1. Part design: polymer parts have an anisotropic behavior compared to isotropic metal parts. This needs to be considered in the part design, especially for injection moulded parts and specific design support during this phase.

2. Material selection: it is important to collect all the application requirements and key performance indicators. Furthermore, once the base design of the part is done, material selection can start. Among the first steps is the translation of the application requirements into material properties. There are frameworks which can support you with the systematic polymer materialselection.

3. Mould design and construction: in this phase, mould design takes place. The mould must be able to withstand the moulding process (injection pressures) and can handle the selected polymer. This is in particular important when moulding of high performance polymers, such as PPS which need a minimum of 135°C tool temperature, is done.

4. Moulding machine selection: after completing the mould design, selecting the injection moulding machine should be done. This step can be done in parallel to the mould design too (depending on the data available).

5. Moulding process: after we have obtained the first parts which passed the quality check, optimization of the process can start. It is the last step and often neglected, however, it allows making the whole production more efficient and economically robust.

Thanks for reading and #findoutaboutplastics



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[1] Distinctive Plastics Inc.:  The 5 critical factors to produce a successful injection moulded product, 2011,

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