The Cadbury factory at Bournville – since 2010 part of Kraft Foods – is using simulation software to manage robotic operations for the production of its Roses and Heroes lines of assorted chocolate selections.
Beccy Smith, associate principal scientist at Cadbury, explains that the site has to maintain a buffer stock of wrapped but unpackaged product, which continually updates for subsequent production runs.
Until recently, each chocolate type was stored in separate cardboard boxes, emptied by hand for packing. However, that meant 170,000 boxes and a lot of manual handling. Hence the move to robots, capable of handling large industrial polypans, and hence also the deployment of Witness to test and validate the production processes and optimise operation of the capex involved.
"Simulation was brought on board to validate the investment and make sure it would do what we needed it to," confirms Smith.
"However, it was not just about proving the business case. The control logic for robots is incredibly complex and even something as seemingly simple as four robot arms soon develops a great deal of sophistication. That means time spent simulating and optimising the control logic can make a real difference to productivity," she adds.
Smith makes the point by explaining that four robot arms, each have six different cell positions used for five full polypans and one set of empty polypans.
"The robot palletises and de-palletises these, as required," she says. "It must balance the handling of the empty and full polypans to balance the flow of pallets. The delivery of the polypans on their pallets, via the conveyor systems from various points in the factory, forms part of this loop. And of course, this is all variable, as production demands change."
Witness was used to model the initial design and subsequently to refine robot timing and sequences, conveyor delivery and operational controls.
"We have gone from multiple cases of manual unloading of boxes to single automatic tipping of polypans that carry 5.5kg of chocolate. We have also reduced our cardboard usage and transport requirement enormously supporting our 'Purple Goes Green' policy," states Smith.
"By simulating and optimising the new equipment and the associated processes, prior to implementation, we have ensured a streamlined efficient process, one that has been implemented smoothly," she says.
"The model is not finished either," she adds. "There are always changes to be made, new trends and initiatives to follow and factors such as seasonal spikes in production to contend with. Simulation will be critical in helping us to plan and react in the future."