Shaftless servos keep press lines rolling

Shaftless servo systems solve production problems at two northern newspaper printing works.

When printing daily and weekly newspaper is your core business, missing deadlines simply isn't an option.

So when two of the UK's busiest printing houses required their ailing newspaper folders to be overhauled, the latest technology from Siemens was deployed to replace existing mechanical drive systems with shaftless solutions and help keep press lines rolling.

At Yorkshire Post Newspapers in Leeds, an ageing folder operating 16-year-old mechanical gearboxes, clutches, linkages and couplings, was becoming a source of constant frustration to the site's engineering team due to repeated downtime.

"The folder was a continuous headache to us", confirms Geoff Taylor, Engineering Manager at YPN.

"If we had a failure of the gearbox/clutch arrangement then the press would be down for 48 hours whilst repairs are carried out".

"This sort of down-time isn't acceptable when there are newspapers that have to be printed".

A newspaper folder is the weak link in a printing press line.

A press can only go as fast as the folder will allow, hence a bottleneck is created.

Folder reliability has a direct effect on printing press productivity and performance.

To remedy the situation YPN enlisted the services of Preston-based Printing Press Services, a specialist in the remanufacturing, installation and commissioning of printing machinery.

Together with Siemens Automation and Drives, the preferred equipment supplier, the two companies set about designing a solution that would drive the folder based on a shaftless servo system.

"We wanted the ability to adjust the drives to suit production requirements", says Taylor.

"The shaftless option was cost effective, trouble-free and provided the capability to 'tune' the drives to the press".

"Without doubt it was the right solution for us".

The Siemens solution split down the mechanical system into individual drives driven by shaftless servo systems based on Siemens 1PH7 air cooled ultra-compact AC asynchronous motors.

Siemens Masterdrives were deployed on a common DC bus, while all synchronisation commands were sent across a Siemens Simolink high speed fibre optic ring bus.

Processing for the set points was performed by one of the Masterdrives, negating the need for an external PLC.

"It was a very successful project", declares Taylor, "but then again, it had to be".

"We don't stop printing, so if there is no folder, there is no press, no Yorkshire Post, no Financial Times, no Metro, etcetera", he says.

"We operate a very busy site".

Fortunately for YPN, the majority of the work could be engineered off-site, with the most of the overhaul and commissioning taking place over just one weekend.

"There were difficult design criteria", says Taylor.

"The mechanical 'envelope' was very tight".

"But I can't fault PPS or Siemens - since commissioning we haven't had any downtime whatsoever".

"This project has increased our reliability, speed and performance, as well as saved us a considerable sum in lost production".

Across the Pennines, an almost identical problem was being experienced at Bolton-based Newsquest Printing .

"One of our folders with mechanical drives was getting a bit long in the tooth", explains Print Manager Paul Barker.

"Gears were failing with regularity, typically around every three months".

"The cost of replacement parts is OK, but we can't afford the costs of downtime".

The situation drove NPL to the decision to modify the folder and introduce the latest shaftless technology, again by employing the expertise of Printing Press Services and Siemens Automation and Drives.

The aim was to engineer a complete turnkey solution including panel build and harmonic mitigation to ensure a clean power supply for the system.

"We wanted Siemens as we have their PLCs on our press", says Barker.

"Siemens drives are excellent and their motors are smaller than equivalent models available on the market".

He goes on to list four main advantages of installing and commissioning a shaftless solution.

"Firstly it has engineered-out the inherent design issues of the folder", he says.

"Secondly, it has eliminated the effects of mechanical drives, such as backlash".

"Importantly, it has allowed us to gain control over speeds, and lastly, we have also got a 2% gain difference to play with".

Similar to the project in Yorkshire, NPL could ill afford any downtime for installation.

However, the skills of PPS and Siemens engineers allowed the controls, inverter, power supply and motor systems to be built and tested off the press.

"This meant that installation and commissioning could be stage-managed in bite-size chunks over a series of weekends", says a pleased Barker.

"It was an important factor for us because this folder handles around 750,000 copies a week".

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