Cut your carbon10 August 2010

Modern electromechanical technology can help plant engineers to reduce the environmental impact of their operations, says Phil Burge

Hardly a day goes by without environmental issues in industry making headline news. Combine this with the cost of fuel sharply rising and the need for many to comply with the CRC (Carbon Reduction commitment) Energy Efficiency scheme, and it is easy to see why some plant operators are under pressure.

Meanwhile, the 2008 Climate Change Act, which made Britain the first country in the world to set legally binding carbon budgets (aiming to cut emissions fully 80% by 2050), adds further urgency. With industry responsible for 25% of the UK's total CO2 emissions, while energy-intensive firms account for 45% of carbon from the business and public sector, the expectation is on industry to meet these ambitious targets.

High profile support has been available from the not-for-profit Carbon Trust for some time – with more than £70 million in interest-free loans provided to industry last year, to replace old equipment with more energy efficient plant. That campaign is saving an estimated 148,000 tonnes of CO2 each year, and for 2010 the value range of loans is from £3,000 to £100,000, with the amount of CO2 that must be saved per £1,000 of loan increasing from 1.5 tonnes to 2 tonnes.

But what else can plant and factory operators do to reduce emissions? One option, currently gaining ground for new machinery, upgrades and refurbishment projects, is to use electromechanical technology in place of pneumatics or hydraulics. No one is suggesting wholesale change: such systems still deliver high force and good repeatability for applications that need them. However, they generally also require supporting pipework and power units – and, in some applications, are unnecessarily powerful, bulky, noisy and expensive. Indeed, pneumatic systems typically consume 10—15% of a plant's electrical energy.

Older electromechanical systems frequently required large motors and costly control devices, as well as gearing mechanisms if high forces were to be generated. However, automation technology has undergone considerable evolution, and modern systems are smaller, lighter weight and less power-hungry than ever. Indeed, today's technology can offer an efficient and cost effective alternative to fluid power, including in precision machine applications. What's more, it eliminates the risk of leakages and contamination of surrounding areas and machinery, and is typically far quieter and requires less maintenance.

Injection moulding is one example of machines formerly fluid powered, but increasingly using electromechanical automation to optimise efficiency and productivity. Not long ago, engineers dismissed electric injection moulding as too expensive. However, a growing number now realise the cost savings over the operating life of such machines, with electromechanical equipment mostly paying for itself, through cost savings of up to £25,000 per annum, in just two years – even for low precision parts production.

Electrically powered injection moulding machines generally consume less than 45% of the power required to drive hydraulic equipment. No great surprise when servo motors draw power only when needed, and spend only a fraction of the cycle time at peak consumption. Hydraulic machines, in contrast, run constantly and generate considerable heat that needs to be removed using chillers. Hence, electromechanical alternatives require just 35% of the cooling energy.

One more point: the superior repeatability of electromechanical moulding machines, due to their streamlined drive trains and closed loop control, means that one of the major costs, waste, is cut. Also, maintenance and unplanned downtime statistics are almost invariably better. Hydraulic moulding machines require pumps, hoses, filters, tubes and valves – all of which need regular maintenance. Meanwhile, the power train of an electric machine normally consists of a ball or roller screws and gearing. As a result, plant operators on average report a rise in uptime of around 2% after converting to an electrical machine, as well as increased productivity.

Another example is an industrial welding robot developed by SKF to provide an energy efficient alternative to pneumatics actuators used the automotive industry. Its compact electromechanical actuator system requires only a fraction of the energy needed for compressed air, meaning up to 90% savings. Indeed, data from one global automotive manufacturer recorded savings of 45,000kWh for four million welds per year per robot.

By the way, that system enables both the speed and quality of the welding operation to be significantly improved on its hydraulic forbears, through greater control of the entire process, while noise and maintenance requirements have also been reduced.

With plant managers under increasing pressure to create the perfect balance between sustainable energy and improved plant and machinery performance, it's time to reconsider electromechanical engineering.

Phil Burge is communications manager at SKF

Phil Burge

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