Claude Bernard, product marketing director, Sepro Group, highlights what to look for in a robot for cleanroom moulding.
An ISO 8 cleanroom at MGS Manufacturing in Germantown, Wisconsin (USA)
Robots are being used with increasing frequency in cleanrooms, for most of the same reasons they are becoming more common across all industries. For instance, robots can improve efficiency, stabilise the process, and enhance workflow. Within the cleanroom market, robots can be used across the entire production process - from moulding to assembly to inspection, traceability and packaging.
Naturally, for use in a cleanroom, like any other piece of equipment, a robot must be designed, installed and operated so as to prevent contamination of the clean space. In Cartesian or beam robots, which are the most commonly used in injection, areas where grease or other lubrication is used must be enclosed so that none can escape into the moulding area. All cables are protected in conduits and pneumatic air is filtered to 0.3 micron. All surfaces are smooth and free of logos, stickers, or other decoration to eliminate places where dust can accumulate and to make cleaning easier. Stainless steel is used in many components - like end-of-arm tooling - that come into contact with the moulded parts.
Sepro 6-axis articulated-arm robots, developed in partnership with Stäubli, have a sealed housing, and the standard robots are suitable for ISO 5 (class 100) cleanrooms without modification. Therefore, injection moulding robots can meet all but the most stringent requirements. In fact, they can exceed the level of cleanliness possible with injection moulding processes.
Installation alternatives
The conventional way to install a Cartesian robot on an injection moulding machine is to mount it on the fixed platen (injection end of the machine) so that the main beam (X axis) extends from the area immediately above the mould and parts are unloaded to the side of the moulding machine. Here they can be placed on a conveyor or immediately packaged. The parts may also undergo secondary operations such as gauging or assembly, using human operators or additional robotic automation.
Robots can also be mounted axially, where the X-axis beam extends from the space above the moulding area along the centre line of the moulding machine so that moulded parts are discharged at the clamp end of the machine. In cleanrooms, this arrangement offers several advantages. Firstly, when parts don’t need to be discharged to the side, it allows the machines to be placed closer together. In cleanrooms where floor space is often at premium, this can be a considerable benefit. Another potential advantage of axial mounting comes into play in applications that require the highest levels of environmental control. The IMM and the robot (installed in axial configuration) can be installed outside of the actual cleanroom, with the clamp end of the machine near a wall with an opening leading into a second room where higher cleanliness standards may be maintained. Parts can be quickly shuttled into the cleaner environment for final processing or assembly.
In any case, the moulding machine and the robot will need to be guarded to protect human operators from injury due to coming into contact with the moving robot. The metal profiles into which guarding panels are mounted should be closed on any side that doesn’t need to receive a panel. Instead of the wire mesh commonly used in general industrial applications, the guarding panels themselves should be made of PET polyester or other clear plastics that can be easily wiped clean. Cables should be routed in closed wiring ducts, and all ducts, drawers, and other components should be stainless steel, electro-polished for easy cleaning. The number of supporting legs on the floor should be kept to a minimum. Similar design rules apply to conveyors.
Robots and automation systems will continue to play a crucial role in medical injection moulding. Automation technology can be expected to continue to advance as market forces demand it to do more, and as robot technology evolves.