This motion picture is a wrap
04 January 2011
Automated shrink wrapping has to be accomplished with care if you are to avoid crushing the cartons being shrink-wrapped. And when you are operating at speed, even greater care is necessary - all of which places a great deal of reliance on the precision and repeatability of the motion control system that determines the wrapping machine’s movements
"Wrapping machine systems are our business" reads the legend that LinkX Systems likes to use in its literature. The Beccles, Suffolk based company, which builds shrink-wrapping machines for the food, beverage and pharmaceutical industries, boasts a product portfolio that includes tray, case and carton erectors, heat wrapping systems, case and tray sealers, case loaders and custom end-of-line packaging machines.
Recently, the company was approached by a large multi-national frozen food firm with a request to design and build a flexible shrink-wrapping unit for one of its production lines. The site for which the shrink wrapper was destined already had ten machines from another supplier, all running at 180 cartons per minute so, at the very least, LinkX’s unit needed to match this performance. The final choice came down to a LinkX Matrix side-feed collating and shrink wrapping machine.
With an Allen-Bradley ControlLogix programmable automation controller at its heart, the Matrix relies on a Kinetix 6000 ten-axis precision servo system to provide accurate and repeatable motion, even when the machine is operating at its full capacity – a respectable 300 cartons per minute, surpassing the existing machines' performance by some 60 percent.
But Rockwell Automation equipment is not just confined to the motion control system; the operator interface is provided by an Allen-Bradley PanelView Plus 10000, while PowerFlex 40 and Powerflex 4M variable-speed drives and a variety of low-voltage control equipment also have a role to play in this machine. LinkX Systems technical director, David Hayward takes up the story.
"The servo motion system acts like an electronic cam, creating a motion profile that causes the least possible amount of ‘stress’ on the cartons being packaged. This is important as there is a limit to the amount of external pressure a carton can take.
"We have also been able to introduce just-in-time agility into the machine, allowing our customer to quickly and easily change the packaging profile, and create different product, batch and volume ‘recipes’. This size change needs to be repeatable and is available at the touch of a button." During the development phase, Rockwell offered the services of Stuart Ashmore, one of its global OEM technical consultants.
"Stuart helped us with the software," Mr Hayward continues. "He made sure we were making best possible use of its functionality and gave us full support in both the developmental work and any necessary training. We knew our decision to work with Rockwell was the right one; our previous automation supplier was good and had also been accepted by our customer, but the Allen-Bradley solution was more than a match, was more price competitive and, moreover, complemented the customer's existing Rockwell Automation infrastructure.
"The 60 percent speed increase is a real plus point for us and the Allen-Bradley servo system played a huge part in us being able to attain this level of performance. The machine is currently running at the customer's plant and we are already hearing that they are thinking of expanding; the 60 percent performance increase really got their attention!"
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