It was in 2012 that manual milling and 2.5-axis CNC milling gave way to full 3-D machining of plastic injection moulds on a three-axis vertical machining centre (VMC) at family-run tool-making and plastic injection moulding specialist Plasticom Group.

Since that time the toolroom has undergone a transformation, with 2020 alone seeing around £250,000 invested, mainly for the purchase of a Sodick die sinker and a German-built Spinner three-axis VMC.

The latter machine was supplied at the end of September 2020 by the UK sales agent, Kenilworth-based Whitehouse Machine Tools, and its installation coincided with the departure of a 25-year-old CNC milling machine.

Toolroom coordinator Ian Alexander had been tasked with investigating the best replacement for it; and while three machines were considered, the Spinner was selected due to the “comprehensive specification of the VC750’s standard version”.

It includes linear scales, 22-bar through-spindle coolant, a swarf conveyor, Blum TC52 spindle probing, 24-station BT40 tool magazine, 12,000rev/min spindle, Siemens drives with up to 36m/min feed rate and the latest Sinumerik 840D control with 24in Industry 4.0 multi-touch display.

Mr Alexander, who estimated that the equivalent package from other suppliers would have cost half as much again, said: “The VMC represented the best value for money by far and the latest Siemens control is a real bonus. It allows us to program cycles to produce complex forms directly at the machine, taking the load off our CAD/CAM department.

“We also like the rigid cross-table C-frame design, which results in high levels of cutting performance and component geometry. The ability to probe a part before it comes off the table and re-machine it if necessary is a big time-saver and makes us more competitive. Furthermore, and depending on the type of component, the Spinner is between 30 and 70% quicker than our other VMC.

“I would say that, on average, it halves cycle times due to faster axis movements, the extra rigidity which allows heavier cuts to be taken without causing vibration, and the latest Siemens control. It offers so much more productive capacity that there will be a lot of spare time to take on additional sub-contract machining, which currently accounts for only a few percent of turnover.”

High-profile customers
Operating from a factory of nearly 20,000ft² in Ashford, Plasticom has long-standing high-profile customers that include household names like Stanley Black & Decker, Games Workshop, Qualcast and Swann-Morton, as well as a host of smaller firms that call on its services.

In March, the company was invited to be part of the UK Government’s Ventilator Challenge UK consortium and staff worked long hours under considerable pressure to ship 15,000 plastic ventilator parts to McLaren Racing to a very challenging schedule.

Plasticom is accredited to ISO13485:2016 and has a class 7 clean room for the assembly of medical devices. Its plastic injection moulding capability is based on machines with ratings from 20 to 530 tonnes, including automation, and extends to twin-shot moulding and overmoulding.

The manufacture of press tools, vacuum forming tools and die casting tools also forms part of the company’s remit, while other services include ultrasonic welding, blister packaging (and other packaging techniques), laser welding and printing.

Now established for 60 years, Plasticom is owned by Edwin Simmonds (chairman) and his wife Sonia (group finance director). Ms Simmonds said: “More than four-fifths of the injection mould tools we make are used in-house to produce a very wide range of parts for customers, a side of the business that accounts for a similar proportion of our turnover.

“Keeping the moulding section operating is therefore crucially important to us, so we look to our machine tool suppliers to provide prompt after-sales back-up. The service that we have received so far from Whitehouse has been excellent, both in terms of the technical input and the training; and while our shopfloor staff have had one week’s tuition so far, no limit has been placed on the amount we will receive in the future, free-of-charge, which is unusual and a great reassurance.”

Mr Alexander says he has adopted a policy of buying in bolsters from Meusburger, so as to allow Plasticom to concentrate on the 3-D milling and sparking of tools. Indeed, a fixture is permanently located on the table of the Spinner VC750 so that each new bolster can be clamped quickly prior to machining of mould inserts within the 760 x 460 x 460mm work envelope, which he says is large for a machine with a footprint of just 2.6 x 1.7m.

Mr Alexander also points out that dimensional tolerances down to “a few microns” are routine and the surface finish achieved is “fantastic”.

In aluminium as well as Stavax, a mirror finish can be achieved using standard mid-price carbide end mills and considerably less polishing is needed overall.”