Electric avenue: are hydraulics and pneumatics being killed off by electric alternatives in motion-control applications? Ben Hargreaves finds that it's more a case of evolution than revolution. (Fluid Power).

ALL-ELECTRIC machines are fast becoming the fashion. If a company perceives itself as being at the cutting edge, it's more than likely to be going for electric systems in its factory.

There are signs that hydraulic and pneumatic systems, the bedrock on which motion-control applications have rested for generations, are under threat from the development of viable electromechanical alternatives. But the consensus is that the new kid on the block will not be taking over quite yet.

Engineers in a wide variety of sectors are becoming increasingly aware of the advantages of electric systems. Some industries are even making fundamental changes to their traditional ways of working to accommodate a greater amount of electric kit. The imminent switch from a 14V to 42V architecture in the automotive industry is a prime example: the change may herald the complete replacement of systems that rely on hydraulics with electric versions.

In April German machine tool company Demag Ergotec launched its first all-electric drive injection-moulding machine, the IntElect Directdrive. Previous Demag machines were driven purely by hydraulics, or were electro-hydraulic hybrids. 'Precision is the main driver for the adoption of electric alternatives,' said Nigel Flowers, technical director at the firm's UK subsidiary. 'There are numerous benefits associated with these electric machines,' he added. 'They are less noisy, and feature greatly improved energy consumption--typically they use 40 per cent less energy than hydraulic machines. Most importantly, they have higher levels of repeatability.'

Electric actuators and cylinders offer a repeatability in the order of [+ or -]0.013mm. They are easier to install and maintain than their hydraulic and pneumatic counterparts as they are cleaner and more reliable. They also have readily predictable life-cycles.

According to Flowers, certain industries have created a greater demand for these all-electric machines. This is particularly true of the medical sector, where all-electric drive systems are well suited to clean room environments.

But it's not just in high-end or very specialised applications that systems such as the InElect are making their mark. 'All-electric technology has become more affordable. Historically it was too expensive for trade shop moulders and so on, but it's now within their reach. We've become better at manufacturing the machines, which is driving down the total cost.'