Sepro Group discusses robotics and automation for cleanroom molding

Claude Bernard, Sepro Group, answers questions about robots and automation for cleanroom molding.

Sepro Group is a manufacturer of robots and automation systems for plastic injection molding. For cleanroom applications, the company uses the same robots as for general molding applications, but modifies them in different ways to suit the customer’s need for cleanliness.

Do you develop any equipment for cleanrooms?

Sepro does not manufacture any robots specifically for cleanroom applications. Instead, we work with our customers to identify what special design features are necessary to allow them to reach their cleanliness objectives. For instance, we ensure that the robot does not release grease or dust in the molding area. Surfaces are smooth and undecorated so that they can be easily cleaned. Stainless steel is used in many components. All cables are protected in conduits and pneumatic air is filtered to 0.3 micron. When the molding machine is installed inside a 100%-controlled environment, the robot may be installed conventionally, with Cartesian robots mounted above the fixed platen and six-axis articulated-arm robots to the side. In ‘gray’ rooms, where contamination is controlled only in the area immediately around the mold space, both Cartesian robots and 6-axis articulated robots often are installed so they enter the machine from the side. This allows for the top of the molding machine to be free of obstructions that would otherwise prevent the laminar flow of air over the mold space. Sometimes we are asked to supply guarding that prevents particulate or other contamination from entering.

What is different in cleanroom equipment than for standard equipment?

Sepro Stäubli 6-axis articulated-am robots have a sealed housing and the standard robots are suitable for ISO 5 cleanrooms without modification. Even Cartesian robots are intrinsically cleaner to operate than the typical molding machine it serves. If the molding machine is clean enough to operate in a given environment, processors can be sure that the robot can also. However, in applications that require the highest levels of environmental control, the machine and the robot may actually be installed outside of the actual clean room. In that case, after removing parts from the mold, the robot might place them on a conveyor or some other transfer mechanism that shuttles them into the clean environment for final processing or assembly. 

Are you seeing an increase in the use of robotics within cleanrooms?

Robots are definitely being used with increasing frequency in clean rooms, but mostly for the same reasons they are becoming more common across the industry: to improve efficiency and stabilize the process. In medical, as in most other industries, plastic parts are getting progressively more technical in design and application and that increases the need for automation. In medical molding and other controlled-environment applications, however, there is the added challenge that variability in process conditions cannot be tolerated. And human operators are the most common source of variability and also contamination. By making a human operator unnecessary, a robot eliminates most of the problems that humans can cause. Other factors driving increased use of robots in clean rooms include the fact that a growing number of medical devices, pharmaceutical packaging and drug delivery systems are made of plastics. This means that molders need to be more productive and more flexible and robots help in that regard as well. 

Can you provide examples of how your equipment is being used in an innovative way?

In addition to the precision and repeatability I’ve mentioned before, probably the biggest contribution robots can make to clean-room molding is in controlled part handling. High-volume production usually requires multi-cavity tooling and in most commodity applications, parts molded in different cavities can be allowed to mingle on conveyors or in bins or boxes. In medical molding, however, every part must be traceable and data about how it was produced must be stored in case of a problem. That, in turn, means that parts must be removed from the mold and handled individually so that it can be traced back to the cavity in which it was produced. Even the best human operator cannot be trusted to be 100% accurate and consistent hour after hour and day after day. A robot can be trusted.

After molding, parts usually undergo some follow-on processing and robots are indispensable here too. A robot can present parts for automated inspection for proper weight, dimensions, optical properties and a host of other variables. It can place the part in fixtures for drilling, welding, assembly or other secondary processes. The robot can stack or pack parts so they are ready for shipment or additional operations… all without operator intervention.