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Flow measurement and control combined with online-thermography

In com-parison to the common temperature measuring method that is using temperature sensors within the mold, thermographic measuring of the molded part is offering some special advantages:

- The here applied camera systems are working significantly more precise, and they are also much more robust than temperature sensors.
- The high resolution of an IR camera is allowing for exact registration of extensive areas and critical points (hot spots).
- If the rare case of any sort of disturbance should occur, the camera can be replaced very quickly and without having to dismount the mold.
The constant temperature control is allowing for optimized cycle times. The technology is advancing the start-up phase, and is leading to less scrap during the start-up phase.

The constant temperature distribution is leading to a lasting quality improvement. Variations in temperature that are not within the tolerance range are detected immediately. The costs that are linked to producing scrap are dropping to a minimum. The realization of the statistical process control gives for example the advantage that mold maintenance can be done early, so unscheduled repairs can be prevented as far as possible. Not least to mention that the thermal “fingerprint” is a comprehensively relevant process parameter.

At K Show 2010 the potential of online thermography has been demonstrated in conjunction with an EcoPower 240/750 injection molding machine. A Wittmann W821 robot was in charge of positioning the finished part – an ABS building block – in front of the camera. The robot was equipped with a rotational axis, permitting to take thermal “fingerprints” of five sides of the part.The analyzed thermographic records are needed for quality management documentation purposes. Beyond that, these values are consulted to control the mold tempering.

After having made the thermal pictures the robot is handling over the parts to a laser inscribing station.The handling system is playing a key role in this process. The heat images can only be done precisely when the positioning of the part is happening with repeated absolute precision. After that they are compared to the target state by software especially developed by the SKZ. The servo technology of the WIttmann robot that is controlled by the R8 software is ensuring that the robot’s movements are absolutely accurately repeated.

Again at this year’s K Show, a Wittmann Battenfeld large-scale MacroPower 1000/8800 Unilog B6 machine showed impressively the efficient interaction of Wittmann auxiliaries and Wittmann Battenfeld machine.The many visitors were in particular taken with the impressive large-scale Water Flow Control system with its 80 cooling circuits directly mounted on the machine. The installation presented to the public a special packaging application: The production of a stackable foldable box was executed – and this box also found great favor with the show visitors.