Stäubli has brought a demonstration cell to K 2016 in order to demystify just how automation solutions for injection moulding can open up a new world of productivity, process reliability and flexibility.
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This automation solution illustrates how easily a complex task can be mastered with integrated Stäubli technology. |
Increasingly stringent demands on the design and quality of injection moulded parts presents a challenge for plastics processors. This coupled with the trend for greater numbers of product variants, which leads to a commensurate reduction in batch sizes, leads to frequent mould changes which, for some manufacturers, can amount to several times per shift.
All of the above has a negative effect on the productivity of injection moulding machines, with the unproductive setup and idle times of these expensive capital goods becoming a serious problem. As a partner to the plastics industry with over 60 years of shared experience, Stäubli is aware of the issues and has come up with a globally unique range of integrated solutions that derive from its core competencies in connectors, QMC (Quick Mould Change) and robotics.
Exchanging injection moulds: Pure unadulterated SMED
Stäubli's stand in Hall 11 has been home to a pioneering demo cell for K 2016, in which all the essential process steps of a fully automated injection moulding machine can be observed. Visitors have been shown how networked Industry 4.0-compatible components enable the individual processes to be coordinated and optimised.
But above all, the realistic trade fair demo application exemplifies the Stäubli concept of Quick Mould Change and SMED (Single-Minute Exchange of Die).
Top of the class in Quick Mould Change
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These superior QMC solutions allow the exchange of injection moulds to be performed to the highest safety standards within minutes. |
The demo cell for trade visitors at K 2016 is a step-by-step presentation of the technologies involved in achieving such outstanding performance. The starting point is the preparation of the injection mould with integrated preheating, during which the next mould in line is being made ready in parallel with ongoing production.
The tricky aspect here is the preheating of the mould, without which there would be a delay before it was ready for use in the machine itself. The operator starts by switching on all media, power and signal connections with a single control on a Stäubli multi-coupling system. If desired, this manual operation can also be performed automatically. Thanks to the superior multi-coupling technology, manual connection takes only a few seconds, and the possibility of faulty connections is absolutely excluded.
The preheating now begins at the work station. Here too, the Industry 4.0 capability of the coupling technology has a positive effect: thanks to integrated sensors, the connectors are able to detect the condition of the mould and feed the data collected into the subsequent process. Any faults, such as a failure to reach the correct operating temperature, can thus be recognised at an early stage. This allows correction of the fault before the mould is inserted into the machine, thereby avoiding unnecessary costs and expensive downtimes.
Safe transport of injection moulds in an Industry 4.0 environment
When the mould has reached the prescribed temperature, it is ready for transportation. In the demo application at K 2016, this demanding task is performed by a die cart on rails. However, manual or induction guided solutions are also available as an alternative. The tool shuttle conveys the new mould from the preparatory station to the injection moulding machine and collects the one previously in use. Even before the machine performs the final shot of the current batch, the die cart with the production-ready mould is standing next to the machine, waiting for the signal to be given for the exchange to start. Now everything has to happen quickly. Firstly, the Stäubli mechanism automatically locks both halves of the mould. The fully automatic multi-couplers immediately disconnect all signalling and media, while the automatic ejector (also a standard Stäubli product) separates the mould. Before the machine opens and releases the mould, it is automatically declamped by the Stäubli magnetic clamping system.
A heavy-duty, electrically powered mechanism now handles the exchange with high precision. The process is, of course, fully monitored by sensors. At one point in the procedure, both moulds are briefly on board the shuttle at the same time. Despite the extra weight, the transport and in particular the positioning of the new mould must be effected with a precision of just a few tenths of a millimetre. Sensors detect the position of the mould and the cart.
To ensure maximum process reliability, the machine and the die cart automatically coordinate their status at every step. The die cart works with the data from both the mould and the machine, adjusting transfer height accurately. The Stäubli tool-centring unit then ensures precise positioning before the mould is magnetically clamped, a process that takes just a few seconds.
The innovative aspect of this is that the IMAG magnetic clamping system from Stäubli controls the actual clamping parameters of the mould and compares them with the nominal values of the machine and the previously defined mould data. If the clamping force falls below the self-opening force of the machine, the intelligent magnetic clamping system adjusts the machine parameters accordingly. As a matter of principle, all measured values including mould temperature are communicated with the machine and logged in the history of that particular mould.
The sophisticated Stäubli concept ensures that the entire mould change proceeds smoothly in under a minute thanks to the interplay of various hi-tech solutions. To ensure compliance with Industry 4.0 management principles, all processes are monitored by sensors.
The world’s fastest Safe Robots
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This combination of extra speed and precision is perfect for work on the injection moulding machine, because during the insertion processes in the mould, it is not just a matter of achieving the shortest cycle times – tolerances in the range of a few hundredths of a millimetre have also to be observed. |
While the majority of the QMC activities run in the background without interrupting production, the injection moulding machine itself is required to operate flat out. Here, it is primarily a question of keeping the mould open time, during which loading and unloading of the injection mould is carried out, to the absolute minimum. The demo application in Düsseldorf is intended to show just how dynamically and precisely Stäubli robots are able to go about their work.
Two robots – a TS60 SCARA and a six-axis model of the new TX2 generation – work hand in hand. The task of the four-axis robot is to pick the inserts intended for moulding, which arrive via a smart feeder system, and to position them on a tray. The TS60 is equipped with a vision system for detecting the inserts.
At the defined transfer position, the ultra-dynamic TX2-90L picks the inserts and commences a cycle that has been optimised down to the last detail. Loading and unloading of the injection mould under the toughest cycle time criteria are the challenge here. It is now clear why Stäubli describes the TX2 series as the world’s fastest Safe Robots.
Despite their extensive safety features, the TX2 six-axis robots are 30 percent faster than their powerful predecessors. And they have even managed to improve performance in Stäubli’s best discipline, namely precision. This combination of extra speed and precision is perfect for work on the injection moulding machine. Because during the insertion processes in the mould, it is not just a matter of achieving the shortest cycle times – tolerances in the range of a few hundredths of a millimetre have also to be observed. The TX2-90L clearly sets the benchmark here: its compact internally-wired arm reaches more deftly and safely into the injection moulding machine than any other robot, thus reducing mould open time to an absolute minimum.
Risk-free human-robot collaboration
And there is one more benefit that the demo application at K 2016 will illustrate: the TX2-90 is not only highly productive but also allows risk-free interaction between man and machine. This is made possible by safety technology with pioneering safety features. The TX2 six-axis robots with CS9 safety controls have a separate digital security encoder for each axis and an integrated safety board. All safety features comply with the stringent requirements of safety category SIL3/PLe.
To ensure maximum safety, every movement of the robot is monitored by sensors. Furthermore, all the coordinates of the robot as well as its speed and acceleration are recorded in real time. In its TX2 series, Stäubli has opted for configurable, safe I/O modules as well as real-time Ethernet field bus systems that guarantee maximum safety and compatibility.
Although the technology behind the safety concept is complex, it is quite straightforward in practice: whenever an employee enters a defined zone, the robot slows its speed – if necessary coming to a complete standstill. The operator can therefore collect samples for quality assurance right next to where the robot is working or perform other tasks such as loading or unloading directly at the gripper.
Automatic gripper changing on the robot
To keep the non-productive times to a minimum, Stäubli has even automated the exchange of robot end effectors. Here too, the manufacturer uses products manufactured in-house. Stäubli Connectors has extended its series of robotic tool changing systems to the bottom end of the scale and now offers exchangers for all load ranges.
At the same moment that the injection mould is being changed, the robot can adapt to the new product variant by autonomously collecting the appropriate gripper at the tool changing station. This is as good as it gets in terms of productivity. To ensure maximum reliability, Stäubli is the only manufacturer worldwide to develop and manufacture all its exchange systems in-house.
Unique in the world: comprehensive skills in solution finding
The Industry 4.0 injection moulding cell with preheating station, automatic mould transport/exchange, automatic magnetic clamping system, advanced coupling technology for fully automated connection of all media, power and signal circuits, and the world’s fastest Safe Robots with automatic gripper changing system represents the future of injection moulding.
There is only one company in the world that can offer the incredible variety of components for the automation of injection moulding machines from a single source, and that company is Stäubli. With its rapid coupling technology, comprehensive range of QMC components and choice of robots, as well as over 60 years of extensive expertise in plastics processing, Stäubli has established itself as a partner to the industry and today offers the widest spectrum of automation solutions, including for use under clean room conditions. Stäubli’s excellence as a solution provider is the key to managing increasingly diverse plastics production with smaller batch sizes. And the integrated nature of the one-stop solutions on offer assures maximum efficiency and unrestricted Industry 4.0 capability.
