FEATURE MACHINE BUILDING & FRAMEWORKS
Cutting costs without sacrificing functionality or safety
“The additional power supplies on the valve islands allow us to have the two- tier safety system, where we can feed valves with a separate 24V supply,” explained Riddington. “This means that when the perimeter gate is opened, some valves are isolated and will not operate while others will. The ‘lower’ tier applies when you open the gate and that only affects the valves associated with movement on the machine. If you hit an emergency stop, power to all the other valves on the machine is isolated, guaranteeing the safety of the process.” PCL Ceramics has recently adopted the
Producers of sanitaryware pressure casting systems, PCL Ceramics, is utilising Festo’s pneumatics equipment and CPX modular automation platforms to save time and become more cost effective
W
hen PCL Ceramics was tasked with decreasing its machine building
expenditure as part of an overall cost reduction programme, automation equipment supplier Festo helped PCL to understand how the latest technology could help it achieve this objective without sacrificing the functionality or safety of its machines. PCL Ceramics develops and produces sanitaryware pressure casting systems with machine configuration options ranging from simple manually de- moulded systems to fully automated robotic systems.
A LONG STANDING RELATIONSHIP As a long term Festo customer utilising traditional products like multi-pin valve terminals, cylinders and air preparation equipment, the company had already introduced the Festo CPX modular automation platforms on its machines around seven years ago. However, as part of a cost reduction programme to help target lower cost markets, it needed to implement further savings. “We did not want to make any
engineering or safety compromises but we realised that we did not need all the sophisticated diagnostic features of the CPX-MPA-S on all our machines,” revealed Nick Riddington, engineering manager at PCL Ceramics. “Our machine is used for casting
sanitaryware and operates in a process type environment where motors pump liquid ‘mud’ into pressurised moulds in a controlled sequence, after which there is a setting period of around 20 minutes. At
22 MARCH 2014 | AUTOMATION
the end of the process, the moulds are automatically opened and a robot enters the process area to unload the casting machine before the moulds are closed for the whole process to start again.” Festo supplies the pneumatics
equipment for PCL Ceramics’ machines but the main benefit that continues to secure the company’s business is the functionality of the CPX system - especially the features like the additional power supply mounted under the I/O modules, which provides additional safety functionality. Riddington added, “The major advantage to us is that we can power the outputs using separate independent power supplies. We can have the benefit of a valve island with many valves alongside each other and then we can operate a completely separate valve with its own air supply which can be at a higher air pressure supplying solenoids on the valve island.”
SAFETY IS PARAMOUNT A major consideration for PCL Ceramics is of course safety, and the entire process area is surrounded by a safety perimeter fence to prevent workers from entering during operation. However, during the 20 minute casting cycle, when there is no movement, staff are allowed into the cell. Therefore, a two-tier safety system is in operation where, if an operator opens the perimeter guarding gate, the robot cannot move and the mould will not open, although the machine carries on its casting process.
Above: Festo’s pneumatic equipment
latest MPA-L valve option on the CPX manifolds on its newer machines. The rationale for this change is that this reduced the cost of the manifolds whilst retaining the full flexibility and function integration of the electrical CPX. A further CPX manifold is used purely as an electrical I/O module without valves while eight others are combined electrical and pneumatic valve combinations distributed around different parts of the machinery. Riddington added, “The ability of the CPX system to offer pneumatic and electrical isolation and zoning allows us to build a cost effective solution that incorporates the safety features we need.” Each station communicates by fieldbus (Festo valve terminals offer more than 20 fieldbus options), effectively providing one ‘control transparent’ line of valve terminals. The new design of single mould machines will use not only CPX and MPA-L but also Festo equipment including rodless cylinders, reservoirs, air preparation equipment and gauges.
Above: the casting of sanitaryware
Below: modular CPX automation platforms
INGRESS PROTECTION Riddington also likes the fact that because the valves and I/O have ingress protection to IP65 and IP67, the CPX and I/O modules can be mounted directly on a machine at eye level instead of inside a cabinet elsewhere, taking up space on the factory floor. Riddington concluded, “The casting process is quite messy with lots of water and mud, and although we mount the valves at a relatively high level, operators wash the machines down with hoses which means that the valves can get wet or dirty.” This combination of pneumatic
equipment with the modular automation functionality of the CPX systems has allowed Festo to assist PCL Ceramics in meeting its requirement to design systems that offer the right functionality but at the right price for the target market.
Festo
www.festo.co.uk T: 0800 626 422
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