Printing, converting and finishing finishing machines beneift from flexible drives

07 March 2012

Every system made by Rotary Logic Systems is bespoke, whether it is high precision security foiling for anti-counterfeit applications, specialised in-line, high speed flexographic/gravure printing processes or sophisticated machinery for the medical industry. One factor is common throughout the machinery range and that is that Control Techniques has been chosen to supply the drives, servo-drives and servo-motors.

UK-based Rotary Logic Systems supplies both stand-alone machines and modules to integrate into all applications in the converting and finishing industries. “We need drives that are flexible in operation, straightforward to program and with very fast response – that is why we use mainly Digitax ST Plus servo-drives from Control Techniques,” said Alan Chandler – director of Rotary Logic Systems. “The speed of response we need on many modules just cannot be achieved with external PLCs. The response times, because the drives’ processors are within the drives themselves, are much faster!”

A typical project is a series of six lines for a manufacturer in India. Each is a multi-stage anti-counterfeit line for packaging, incorporating high-precision application of a hot-foil hologram. The lines have web widths of 1320mm, and each comprises unwind and in-feed, foiling, flying head die-cutting, flexographic printing, out-feed and rewind. There are a total of 30 drives on each line – 9 kW Unidrive SP drives control the unwind and wind operations, while Digitax ST Plus servo-drives twinned with Unimotor FM motors control the feeds and all other processes. A variety of SM-Application modules are employed on many of the drives – including SM-Register, SM-Ethernet, SM-I/O – and the whole line is co-ordinated using Control Techniques’ own high speed network, CT-Net, with the web material drive acting as the ‘master’. There are two points of registration – one to the pre-printed material and one to the applied product. A repeatable accuracy of ±0.1mm is required for the foiling process – and this is achieved with a line speed of 80m/min.

“We had to devise a system that maintains accuracy of application on an inconsistent substrate,” said Chandler. “This has been achieved within the software – Control Techniques has worked alongside us for two years to help develop this – and we believe it is unique in the finishing market.” The software compensates for errors for every image, keeping each within tolerance.

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