At Doncasters Precision Castings in Bochum (DPC), precision moulding is used to produce blades and vanes for stationary gas turbine power plants and aircraft engines. The factory, which has more than 500 employees, relies on an extensive vertical range of manufacture and produces its own moulds. The responsible engineers are currently optimising their plants using their own capacity. For example, a robot gripper in the fully automated mould production has been retrofitted with a sensor. The task of this sensor is to detect whether or not a bolt is fully extended, securely fixing a wax cluster before the robot dips it into a basin and moves it around to ensure that the ceramic liquid also reaches into any undercuts (Fig. 1).
This type of request is easy to realise, for example using an inductive sensor. Because in such cases the gripper has to be able to rotate 360o, it is not possible to have any power or signalling cables in the way. The logical solution: a (battery-powered) sensor which transmits a wireless signal "bolt fully extended".
The maintenance engineers at Doncasters required just such a solution. Their search ended successfully with a visit to the website of steute business division Controltec. They agreed with steute that an RF IS M 12 cylindrical wireless inductive sensor should be selected (Fig. 2). Both the power supply (via battery) and the signal transmission are achieved by a separate, compact module (Fig. 3). It uses the sWave wireless technology developed by steute and guaranteeing reliable signal transmission to the corresponding receiver unit even in adverse industrial conditions.
A first wireless sensor was initially tested on a robot gripper. The result: the position monitoring worked perfectly, even in threshold areas; the robot only started when the bolt was fully driven into the gripper. Any damage to the plant or moulds could thus be ruled out. The consequence: Doncasters will now successively retrofit all robots used in its mould production with steute wireless sensors.