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Why continuous innovation is needed within the plastics industry

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David Russell, general manager of consultancy David Russell Associates, talks about innovations within blow moulding and thermoforming.

“There is a better way for everything – find it!” – Thomas A Edison

“If you always do what you’ve always done, you’ll always get what you always got!” – Henry Ford

These statements are as applicable today as they were 100 years ago. We have to continuously innovate or someone else will! We have seen how 21st century computing power has driven innovation and reduced costs – but not everywhere in the plastics industry.

Computer simulation has been a fundamental step in design for injection moulding for more than 40 years. But, even with the advent of industry 4.0 principles, the massive benefits seen through simulation in the injection sector have not been replicated in blow moulding or thermoforming, where it is sometimes regarded as a cost, rather than a benefit.

Product strength in ‘closed mould’ plastics processes is achieved by controlling the wall thickness within the mould. But in blow moulding and thermoforming the thickness is dependent on how the material will stretch during moulding. Experience has always been used to predict stretching but for many complex 3D designs experience is not enough – modern computing power has to be used to optimise cost and performance.

Simulation software, when used to optimise design, tooling and heating, can improve technology, efficiency and competitiveness. Organisations who have adopted simulation are reaping the benefits in new products by:  

In the blow moulding sector, simulation software will automatically optimise the shape and temperature profile of preforms and parisons. In thermoforming, simulation software will automatically optimise the oven settings to achieve best thickness.

Once organisations gain experience in simulation, it is being used to optimise existing process settings to reduce cycle times and costs. One packaging thermoformer investigated the effect of varying their machine settings by +/- 15%. This meant looking at the effect of 16 variants such as something which would have incurred an inordinate amount of people time, machine time and wasted materials. They turned to simulation to carry out the investigation by ‘batching’ the variables, and within a few hours they were able to compare the different thickness outcomes to arrive at better settings. For zero cost they took 10% out of cost, resulting in 12.5 tonnes of sheet saved annually. This meant that one job more than paid for the software.

Also, of increasing importance prior to tooling, is the use of Finite Element Analysis (FEA) to check that products will meet performance criteria. It is important to note that the accuracy of FEA is dependent on the accuracy of the data it is fed with. Meaningless ‘nominal thicknesses’ predictions will no longer be enough for FEA, and computer simulation will be needed to provide accurate details of the thicknesses across the whole product.

Consultant, David Russell, played a key role in introducing the innovative high pressure forming technology to Europe 30 years ago and wishes he had been able to use simulation back then in design discussions with customers, and to better identify quality issues (e.g. thinning) before tools were ordered. Russell now promotes innovation via simulation and heating.

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