British innovation: Inventing a new concept for injection moulding

The invention of technology for the plastics industry is not new – the machines that manufacturers are reliant upon today were borne out of the ideas of those individuals trying to make the process that little bit more efficient, more productive and more cost effective.

However, in an age where plastic manufacturers run a daily gauntlet against rises in material costs, energy prices and environmental targets, technical innovation is championed as the very sinew of a strong and enduring economy. British Plastics and Rubber is proud to champion those companies in the UK that are developing new technologies that are both socially responsible and economically viable.

One such company, The R&D Factory Ltd., is a small UK business promoting Streamoulding, a technology for injection moulders that is at the forefront of innovation. Leanne Taylor spoke to John Heaton, one of the company’s directors, to find out more about this ground breaking invention.

The R&D Factory Ltd. is a small business based in Flintshire in North Wales, with just two directors at its helm. Through its mantra of inventing socially responsible products and processes that generate definable and quantifiable environmental benefits whilst reducing material and energy costs, the company has developed Streamoulding, a retrofit system using tap water to foam the polymer in the nozzle of an injection moulding machine.

“It is well known that water is a contaminant in moulding and that polymers are dried before processing to stop any reaction,” explained John,  “which created a number of ‘what ifs’ in terms of how we could use water in a way in which it could be beneficial.”

“These included whether the reaction of the water within the nozzle could be controlled, whether it could foam one shot at a time and if the foam could be created during injection into the mould. We also considered if this could be done on existing injection machines using ordinary tap water.”

Even if it were technically possible to create a product, the company had to consider whether the process would be commercial, whether it would be affordable, and whether it would save money.

“Initially we had to prove the concept, which we did by getting a very crude reaction to take place in the plunger cylinder of an old Netstal machine. Notably the material was dry and unchanged in the screw, barrel and hopper. It was at this time that we decided to concentrate on developing this process to occur in the nozzle only.”

John explained that keeping the system relevant to ordinary production processes was vital. “We had to ensure that whatever we were doing we could do it reliably and consistently in normal production conditions and environments. We have kept all our engineered solutions as simple as possible throughout the project.”

In terms of innovation, John explained that the company had invested time in conducting a patent search to see if the idea had already been conceived. “From our own knowledge and market research, we couldn’t find any water foaming system available commercially,” he said. As a result, the company now has a UK patent for the technology and applications in process for patent protection overseas.

So how does the process work? John explained that there are essentially four stages to the process, which happen more or less simultaneously.

“With the Streamoulding system everything on the moulding machine remains the same up until the nozzle, which is replaced by the Streamoulding mixing nozzle. When the polymelt enters the nozzle it passes through a diffuser with a precise number of profiled holes. These are designed to break the shot into a number of mini melt streams. 

“Triggered by the injection cycle on the machine, a small and adjustable amount of water is delivered at up to 420 bar and is injected in a time which can be as quick as 3 hundredths of a second. The water passes through a specially designed viscosity valve located on the mixing nozzle and into the nozzle chamber. This valve maintains a seal between the pressurised water and the molten material. The timing and duration of the water insertion in respect to the injection cycle, is fully adjustable.

“By introducing the water at this point, it immediately turns into vapour and saturates the mini melt streams. This reaction causes foaming and an immediate loss of latent heat. We reckon this is in the order of 60˚C in one hundredth of a second. This heat is then replaced by the system to enable normal operating temperatures to be maintained and reactivate the mixture. This mixture has now got a reduced viscosity and now passes through a second diffuser and then a static mixing mechanism. This is a very rapid process with the water reacting simultaneously with the skin and the core of the mini melt streams.

“This reduced viscosity foamed mixture is then rapidly injected into the mould. The cooling time is significantly reduced and the mouldings are ejected dry, at around 60˚ C. Any moisture is vented off through the mould.”      

In terms of the unique selling points of Streamoulding, John believes savings in weight and therefore polymer cost, as well as the shorter cycle times resulting in a reduction in energy costs are two of the major benefits.

“Unique to Streamoulding is the fact that no changes to the moulds are needed and the whole system is retro fit and can be fitted, set up or removed if needed, in a matter of hours. Some of the investment scenarios I have completed show payback periods can be less than 12 months.”

A Streamoulding unit costs less than £20K, with John stating that affordability was at the forefront of the team’s minds when developing the system. “We decided at an early stage that the purchasing experience for our customers should be as straightforward as possible,” John explained. “There are no licenses involved, and the lead-time is 4 – 6 weeks. We are keen that Streamoulding is within the budget of small to medium companies and we feel that this in itself is an additional USP.”

In terms of the on-going development of the technology, John explained that there are plans in place to complete trials using rapid mould heating, as well as developing the system to be used in extrusion as well as with biomaterials.

“Due to the cross linking of molecules that we believe is happening during the Streamoulding process, we have successfully moulded dissimilar materials from mixed plastic waste without delamination which opens up the possibility of exciting new markets. We have also done some initial work where we used Streamoulding to successfully mould PP and PS with a biomass filler. We tried rice, corn and oats to get some idea of what would happen with each. We are looking to move ahead with these projects in collaboration with suitable partners.”

Commercially, there seems to be exciting times ahead for The R&D Factory.  Major companies have shown interest in using the technology, as well as researchers from UK universities.

Streamoulding is a registered trademark of The R&D Factory Ltd