Hearing aid device manufacturer Oticon required a more flexible robot to handle the tiny hearing device components in its production. The company had been using robot technology for the past 10 years. But, as the minute components became increasingly smaller in order to make the hearing aids more comfortable, the existing two- and three-axes robots used in manufacturing were no longer suitable. They could not perform the required lateral and vertical movements sufficiently. If for instance a small part is stuck in a mould, the robot should be dexterous enough to tip it out.
“The parts for modern hearing aids are getting smaller and are often only a millimetre in size. We looked for a solution that can suction small parts out of a mould. This was impossible manually. We needed a more flexible solution that would also be economically viable for smaller production runs,” said Arne Oddershede, group leader of the maintenance unit at Oticon.
Intuitive user guidance and the precision of the Universal Robots, were the features that convinced Oticon. Also, rapid advances in medical engineering have resulted in constantly changing production processes and a broader range of hearing aid models that require a flexible robot handling smaller batch sizes. Small components such as wax filters are barely a millimetre in size.
Mounted firmly to the injection moulding machine, the robot can position itself over the mould and suction the plastic elements using a specially designed vacuum system. This is possible due to a suction tool that can accommodate up to four tiny components simultaneously. The UR5 from Universal Robots is programmed to only engage the suction mechanism when the mould is open. Once it has taken the parts, the robot draws away, and the injection moulding machine prepares for a new operation. All the components from the same mould are subsequently collected in separate tubes to ensure that they can be traced correctly. The vacuum system also ensures that the sensitive elements are not damaged.
Because of its six axes, the UR5 is very maneuverable and can rotate or tilt the parts in order to lift them quickly out of the mould. The robot works in four- to seven-second cycles depending on the size of the production run and the component. More complex moulded components are handled with pneumatic gripping tools.
It took just one day to install the robot for its new task in Oticon’s moulding shop. “Since we produce different batch sizes and components when developing new products, it must be possible to easily reprogram the robot. With a traditional robot, this involves a computer and requires specially-trained staff, typically a programmer. But with the UR5, any member of the technical staff can literally grab the robot and show it the motion sequence using waypoints,” he continued.
The robot comes with a fitted safety mode that allows staff to work alongside the robot without any additional safety shielding. There is a sensor installed in each joint that notices when the robotic arm requires more force for a given movement than previously calculated, for example when an arm or a foot is in the way. The robot will stop working immediately if a counter pressure of 150 Newton is detected. This safety mode has been certified by the Danish Technological Institute in accordance with the European ISO Standard 10218.
