All-electric sustainability

04 May 2020

Engineering capacity news posted by Andy Sandford

All-electric injection moulding machines have allowed Midlothian-based McLaren Plastics to cut its energy usage by 60%.

Recent tests performed by Sumitomo (SHI) Demag on two new IntElect2 50 tonne machines installed in 2019 showed that not only has the family-run moulding business become more sustainable, it has also saved in excess of £7,000 a year.

In mid-2019, the company purchased two all-electric high specification machines to replace two older hydraulic Demag moulding machines. In order to secure an interest-free loan with Resource Scotland, the company needed credible evidence that the investment would result in reduced energy consumption and a more sustainable carbon footprint.

Installed in 1995, for over two-decades, the Demag hydraulic workshorses had been operating 24/7. The initial measurement, performed by Sumitomo (SHI) Demag’s Technical Manager Nick Stockton revealed that each legacy machine was consuming 7.2 kilowatts for each kilogram of raw material converted per hour. At the time of placing the IntElect2 order, Sumitomo (SHI) Demag estimated that McLaren could save on average over 5kw per hour replacing both hydraulic machines with all-electric ones. This was enough to satisfy Resource Scotland, which approved McLaren’s loan grant.

In order to provide a like-for-like comparison, Nick revisited the moulder in early December 2019. Both machines by this stage had been fitted with the same ancillary equipment, replicating the mould vent and cavity balance configuration and exact processing conditions.

“Running the same product at the same cycle time before and after new kit is installed, with all ancillary equipment plugged in is the only true way to gauge the energy and performance improvements,” explains Nick.

Two separate 30 minutes tests were performed, with McLaren intentionally selecting challenging automotive and packaging applications with tight processing tolerances.

The first measurement comprised a square packaging black end cap, using a single cavity mould, with a shot weight of 8.2 grams and 11.5-second cycle. As with the ErgoTech 35 compact test, the IntElect 50 tonne machine was equipped with a sprue picker, a temperature control unit (TCU) and loader, but no granulator.  Previously consuming 4.52kw p/h at an average cost of £0.56 p/h, the results for the new IntElect2 dropped to 1.93kw p/h, saving 58% and the company £0.32 p/h, or over £2,700 annually for a machine operating 24/7.

The second test measured the production of a white automotive bracket for a premium passenger car. With a shot weight of 29.9 grams and a 31.5 second cycle time, the component comprises two different parts moulded in a 1+1 cavity tool. A tool heater, material dryer, TCU and loader were connected to both machines during both 30-minute tests.  A 62% energy saving was documented on the IntElect2 test, reducing from 7.33kw p/h to 2.81kw p/h. Calculating the physical costs and how this could impact the bottom line for a moulding business, this reduction in energy usage equates to a saving of approximately £4,360 per year.