Going the robot route stacks-up neatly for Marley
01 May 2009
No newcomer to robots, Marley Eternit has recently completed installation of two new robot systems at its Burton-on-Trent tile manufacturing plant to replace older dedicated machinery and to accommodate additional capacity transferred from another facility
Marley Eternit engineers have always managed their robot installation projects in-house, taking the role of ‘prime contractor’ when working with supplier partners. Each new project sees a rigorous tendering process, which focuses on experience in the aggregates and construction sector, and a recent job at its Burton-on-Trent tile manufacturing plant, was no exception. Steve Herriott, Marley’s head of engineering, takes up the story.
“Our options to replace 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. Fanuc Robotics was chosen as the supplier and robot system integrator on the basis of experience in our sector and their understanding of the aggressive nature of the product, and its effects on equipment.“
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 a six-axis R2000 Robot, which handles two stacks of tiles simultaneously and places them on a larger vertical stack for further handling by a six-axis M900 with 600kg capacity.
Tiles entering the system are diverted to either one of the two cells and stacked in two piles for the R2000 to pick up. The height of each stack is measured by means of a straightforward through-beam sensor as the sizes of tiles and stack height can vary typically by +/-15mm. The robot stores this information and is able to adjust its positioning when placing the tiles to avoid collision and damage.
The R2000 places tiles in the vertical position, a configuration that is of considerable advantage to this application. The M900 gripper is able to support the stack weight from beneath and use its closing action to align the sides of the stack instead of applying a potentially damaging gripping pressure. This process had not been possible on Marley’s previous tile pick up systems as only four-axis heavy-duty robots had been available. With its 2.8m 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. The process eliminates the incidence of breakages and ensures pallets remain consistent during transportation.
The dimensional accuracy of aggregate components is a major issue that Marley Eternit has to address and Fanuc supplied the all-important grippers so that trials could be carried out prior to installation. Fanuc also rigorously tested the sensor system to prove its accuracy and ease-of-integration with the R2000 robot.
The system is now operating two shifts per day, seven days per week at a capacity of 150 tiles per minute. 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 comprising two robots. Output from the cell is 120 tiles per minute. Marley Eternit now has ten robots at the Burton-on-Trent factory and has become something of an expert in their application within the construction aggregate materials handling sector.
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