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Emerald Group Publishing Limited
Copyright © 2009, Emerald Group Publishing Limited
Robot route stacks-up neatly for Marley
Article Type: Mini features From: Industrial Robot: An International Journal, Volume 36, Issue 6
No newcomer to robots, Marley Eternit Ltd, has recently completed installation of two new robot systems at its Burton-on-Trent tile manufacturing plant. Comprising six FANUC robots in total, the systems were needed to replace older dedicated machinery and to accommodate additional capacity transferred from another facility.
Marley Eternit engineers have project managed all robot installations into its plants and take the role of “prime contractor” working with supplier partners. Each new project sees a rigorous tendering process which focuses on experience in the aggregates and construction sector.
Steve Herriott, Head of Engineering, Marley Eternit, explains, “Our options to replace the existing ‘dedicated’ automation equipment were straight-forward. Using robots we knew we could save over three minutes on each product changeover and as we have eight profiles and up to 40 changeovers per shift the robot approach would increase capacity. Another factor, for the additional capacity transferred from another site, was simply that the equipment was old and probably wouldn't have made the journey!”
“FANUC Robotics was chosen as the supplier and robot system integrator on the basis of experience in our sector and its understanding of the aggressive nature of the product on equipment” (Figure 1).
The four robot system has one line feeding into it and effectively two identical cells of two robots each to handle the throughput. Each cell has six-axes R2000 Robot which handles two stacks of tiles simultaneously and places them onto a larger vertical stack for handling by a six-axes M900 with a 600 kg capacity.
Tiles entering the system are diverted to either of the two cells and are stacked in two piles for the R2000 to pick up. The height of each stack is measured by a straight-forward through beam sensor as the sizes of tiles and stack height can vary typically by ±15 mm. This information is stored by the robot which is able to adjust its positioning when placing them down to avoid collision and damage.
The FANUC Robotics R2000 robot places the tiles in the vertical position which provides considerable advantage as the gripper of the M900 is able to support the stack weight from underneath and use the closing of the gripper to align the sides of the stack instead of applying a potentially damaging gripping pressure. This process had not been possible on Marley Eternit's previous tile pick up systems as only four-axes heavy duty robots had been available.
With its 2.8 m reach the M900 robot is fully utilised in the cell – before palletising the tiles it positions them vertically, while sill clamping them neatly in its gripper, into the strapping machine. A single strap holds them securely and allows them to be stacked neatly onto the pallet.
This process has had a significant effect in eliminating breakages and ensuring pallets remain consistent during transportation.
Compared to automotive type installations, the dimensional accuracy of aggregate components is a major issue that Marley Eternit has to address and grippers were designed and supplied by FANUC to allow trials to be carried out prior to installation. The sensor system was also tested rigorously by FANUC to prove its accuracy and integration with the R2000 robot.
The system is now operating two shifts per day, seven days/week at a capacity of 150 tiles/min. This was achieved after a three-month installation and commissioning period which included operator training at FANUC's Coventry training school.
Although packing smaller tiles, the second system comprises a single cell with two robots. Output from the cell is 120 tiles/min.
At the Burton-on-Trent factory alone Marley Eternit now has ten robots and has built up significant expertise in their cost effective application to handling of construction sector aggregate materials.