CAD/CAM Creating rotational mould tools using high-end software
UK - Edgecam software is playing a pivotal role in assisting a precision engineering company become a growing contributor to the niche market of supplying mould tools to the UK’s rotational moulding industry.
Having invested in a further two new Haas milling machines and a new high specification computer to handle the specific requirements of producing rotational mould tools, UK-based company Turnell and Odell say they simply could not manufacture them without the appropriate software.
Rotational mould tools required millions of lines of code
CNC Milling Supervisor Lee Billingham says they have recently created two-metre-long rotational mould tools for construction industry pipes which required millions of lines of code. “We needed 1.2-million lines of code just for one operation. It would be absolutely impossible without Edgecam.” The Northamptonshire company produces rotational mould tools ranging from 200 mm cubes to two metres for a number of industries including construction, medical and food. Rotational moulders create their plastic products by feeding polymer plastic granules into the mould, which is then placed in an oven and rotated, usually around two perpendicular axes. When heated, the softened plastic is thrown against the sides of the mould and hardens into the rigid product in a cooling chamber. It keeps spinning throughout the heating and cooling cycles.
Maintaining a uniform wall thickness
Turnell and Odell’s Production Director, Kevin Rees, says rotational moulding tools are highly complex because a uniform wall thickness has to be maintained. “Anything in the internal features which is going to create the actual plastic product has to be mirrored on the outside, to ensure the wall stays at a constant thickness.”
He says the file sizes are considerably bigger than for normal machining, because of the tools’ complexities. “The demands put on Edgecam for the piping moulds were extremely heavy, but the software dealt with it so easily that a half-day’s programming for one part of the mould created code for a full 24 hours' machining. We always aimed to have the programs ready towards the end of the day, to make the most of lights out machining.”
Customers provide them with models of the finished plastic product they want to make, then Turnell and Odell design the mould tool in SolidWorks by creating a block around it and shelling away to produce the internal features. “We always need to think about shrinkage, and it needs drafting out to ensure the product comes away easily from the tool.”