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Case Studies

RX Robots Bring Added Flexibility to the Molding Shop

Stäubli Robotics

Automated Assemblies Corporation (AAC) of Clinton MA, specialists in flexible automation solutions for the plastics injection moulding industry, have joined forces with Stäubli to bring to users the additional benefits of six-axis robotics.

AAC have always been associated with the development and application of new technologies aimed at reducing operating costs, improving product quality and increasing productivity. They introduced the first US manufactured IMM part removal robot, graphical user interface and the industry’s fastest top-entry robot. Now, working in partnership with Stäubli, the specialists in six-axis robots, the speed, precision and flexibility of RX robots are being integrated into their automation packages.

Not so long ago the only automation you would see in a typical plastics moulding shop would be simple 2 or 3 axis Cartesian demoulding systems. Today, you are likely to be confronted by ranks of six axis robots performing insert loading, glue laying, de-sprueing, painting and a host of assembly and inspection tasks all within the normal demoulding cycle.

One recent automation solution provided by AAC required a robot capable of a wide range of motion, tight cycle times and the flexibility to easily accommodate changes in the current part design as well as future new products. AAC called in Stäubli to advise on the most suitable model for this application. The RX60B robot with the CS8 controller was selected to be included in the AAC integrated IML workcell to transfer the labels to the AAC Raptor robot for precise insertion into the mould.

RX robots provide all the advantages of the simple Cartesian systems (high speed, slim forearm and simple programming) but have none of the limiting features that restrict the incorporation of additional tasks. The 6 degrees of freedom in movement provides an extremely large work envelope within a small footprint. The robot can be floor, wall or ceiling mounted and is able to accommodate both top and side loading moulding machines. The robot can even be positioned to service two adjacent injection moulding machines.

A typical example of the demoulding speed is the unloading of a Fanuc roboshot injection molding machine with a Stäubli RXplastics90, 6 axis robot. The gain in the cycle was about 40% at 0.61 seconds compared to 1.0 second with a competing 6 axis robot. Even at high speed the robot’s trajectory performance assures a perfect unloading motion through only a 125 mm opening of the molding machine.

For applications where additional tasks need to be incorporated into the demoulding cycle, RX robots really come into their own. The moulded part can be trimmed, de-sprued, reoriented if necessary and loaded directly into the output container by the robot, all sequences usually completed within the operating cycle of the injection moulding machine.

Labels for in mould decoration can be placed into the moulds by the robot with a precision of <0.5mm by using specifically designed double sided gripping mechanisms on the robot arm. Moulds featuring 4 or even 8 cavities can be filled each with a different decorative label if required. This decoration technique has been widely used in the electronics and telecommunications sectors where coloured and patterned parts have been produced by the million.

RXplastics robots are available in three models (RXplastics60, RXplastics90 and RXplastics130) with load capacity up to 25kg and a maximum reach at the wrist of 2185mm. The robot controller comes pre-loaded with Euromap 12 (Europe) or SPI (USA) interface software, widely used across the plastics sector to co-ordinate robot movements with the operating cycle of the moulding machine.

AAC installed multiple cells of the new system at their customer during November and December 2003. Ten RX60 robots were required. This workcell solution now forms part of AAC’s range and will form the basis of a common platform that can be utilised on other similar applications. Additonal functionality such as vision correction for part placement may be incorporated.

The Stäubli Group has nearly 50 years experience in supplying the plastics market; their high performance couplings are widely used for quick release connections in the moulding shop. Stäubli appreciate the need for cost effective, high quality products; the introduction of 6-axis robots with simple control software is the latest in a programme of innovation for the plastics sector. Automation specialists, such as AAC, working in co-operation with Stäubli, are ensuring that these benefits are made readily available to the injection moulding market.

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