Linear progression

Users of industrial automation are more likely to specify linear motor systems – fully assembled modules that are ready to use – rather than buying separate components. A report from consultancy IMS Research says that the global market for linear motor systems last year – at around $354m (£187m) – was twice that of the separate components. According to the company, there is a growing trend for end users to specify systems rather than buying separate components and assembling them in-house. The trend is set to continue. While systems are expected to grow at around 11%, component growth is unlikely to exceed 9%. The Europe, Middle East and Africa (EMEA) region accounts for half of all worldwide components sales, but only one-fifth of systems sales. This is because Europe is dominated by the machine tool industry, which prefers to develop its own systems. Asia is more focused on semiconductor machinery, in which the linear motion element is a sub-assembly – so is bought pre-assembled. As awareness of linear motors increases – and their cost continues to fall – more industries are considering their benefits, says IMS. While the semiconductor industry was an early adopter of the technology, applications here have dropped to around one-fifth of all sales. IMS says this is because suppliers have diversified away from the industry to lessen their dependency on it. The machine tools market accounts for one-third of linear motor sales in EMEA. Despite this relative maturity, one machine tool company claims to be using the motors in a completely new way. Water Jet Sweden says it is the first manufacturer to use linear motors in waterjet cutting machines. Following years of collaboration with CNC supplier GE Fanuc, it has introduced linear drives across a range of profilers made at its Ronnenby factory in Sweden. The entire X-axis of the machine is fitted with a flat magnetic plate, allowing X-axis movement of each cutting head to be controlled by the CNC to an accuracy of 0.05mm. "As well as the well-known advantages of such a drive system, it is especially useful for multi-head profiling," says Lennart Svensson, managing director of WJS. Svensson says that 'nested' items are often cut using the 'common line' method – in which intermediate heads cut a line that forms the inside edge of one component and the outside edge of another. Because each head can be positioned independently, it can be replaced more easily when it wears out. Other potential advantages of using linear motors – aside from the overriding "long term positioning accuracies" – are the lack of backlash and pitch errors. While opportunities for linear motors are emerging in lower cost industries – such as material handling and packaging machinery – IMS does not expect them to be widely adopted in such price-sensitive markets in the near future. "However, linear motors are expected to filter in to these industries at the top end as they replace more traditional technologies," says the report. ******* Linear motors are one of the subjects covered in next month's Linear Motion Masterclass – the first of Eureka's series of Design Days. The event, held at the Kaetsu Centre in Cambridge on 5 October, will explain the latest techniques in linear systems design – through technical presentations and training workshops. The event is supported by four suppliers of linear motion systems – Aerotech, Igus, Renishaw and THK. These companies will lead a series of practical design workshops in the afternoon. For more details on the event, email designdays@eurekamagazine.co.uk.