Charnwood Foods in Leicestershire, which is a part of the RHM Group, is a specialist manufacturer of pizza bases for restaurants across Europe and the UK. The RHM Group has over 50 sites and produces bread, cakes and baked goods for the wholesale and retail market.
In late 2005-early 2006 Charnwood invested in a new multi-million-pound pizza-base production facility at its Wigston site. The new manufacturing line was set up to handle an increasing demand for pizzas. The facility has made Charnwood one of the leading manufacturers of these frozen dough discs in the UK with a production of over 63 million bases a year (this is the second manufacturing line).
The bases are produced from the raw ingredients and are then frozen (using a Starfrost spiral freezer and chiller with a low-charge ammonia refrigeration plant), stacked, wrapped and boxed before palletising. The packaging allows for 12 different sizes of case to accommodate the pizza bases of different diameters.
The facility was constructed and outfitted by Crown Conveyors and robot palletising equipment was provided by Motoman. The pizza base cases are palletised at a rate of 320 cases an hour (40 cases a pallet, eight pallets an hour) using a Motoman SP100XF four-axis palletising robot with a Unigripper vacuum suction gripper.
The Motoman retains a series of pallet layout programmes that can control the packaging operation. In the process the robot picks up the designated number of cartons, usually around three from the end of the production line and then stacks them in an arrangement onto a pallet (case weight is between 16kg to 19.5kg). The robot cell also incorporates a pallet wrapping station with a turntable that can wrap and secure the load prior to placing on a parallel conveyor and then storage in a warehouse prior to shipping.
David Harrison, engineering manager at Charnwood Foods, commented: "the Motoman robot is proving reliable in operation, and very flexible. It was always foreseen that a robot would be used for the palletising operation, as it would be an arduous and repetitive task for an operator to perform. Indeed, palletising at the end of the first manufacturing line has been carried out successfully by robot for the past eight years."
Motoman SP100 robot
The Motoman SP100 robot is a four-axis vertical jointed arm robot that can handle payloads as heavy as 100kg. The vertical reach of the equipment is 3,371mm and the horizontal reach is 3,291mm.
This type of robot is ideal for this type of palletising operation where there is a repetitive, continuous movement of heavy loads. The expanded work area and increased speed of the robot allow it to service multiple infeed conveyors or pallet stations if required.
The SP100 XF – now superceded by the SP160 with an increased payload of 160kg but there are models to handle payloads from 80kg to 500kg – uses the MRC or XRC robot controller and PC-based offline programming is also possible by using the ROTSY-PAL software (VisualPallet and VisualMixPallet). In installations of this type safety is of paramount importance and for the SP100 standard shock sensors confer the ability to instantly stop the power in case of interference with the robot arm.
The Motoman SP100 XF is actually the version of the robot designed for low-temperature operation as in the case of handling cases of frozen pizza bases for Charnwood Foods.
The robot has built in heaters and internal airstreams to maintain internal temperature. The modified robot has the ARC 2001F controller, which has an insulated cover to resist low-temperature environments.