Predictive Maintenance More accurate than the Oracle of Delphi
Traditionally, maintenance means interruption of processes. When there is no clear prediction of when maintenance is needed it can also mean that it is done too often. Predictive maintenance can reduce the number of maintenance routines and therefore increase the time a machine is available.
In classical antiquity, the visions of the future revealed by the Oracle of Delphi were often enigmatic and even incomprehensible. By contrast, the production scientists of the Fraunhofer Institute for Production Systems and Design Technology (IPK) are able to foresee the future of machine tools a lot more clearly and accurately with the aid of predictive maintenance: it helps its users to identify the optimum juncture for maintenance work, to avoid lost production, and to optimise the processes involved. In our interview, Eckhard Hohwieler, Head of Production Machines and Line Management, and Claudio Geisert, both from the Fraunhofer Institute for Production Systems and Design Technology (IPK) in Berlin, report on the salient considerations and the role the EMO Hannover 2017 plays in their work.
Eckhard Hohwieler, how does predictive maintenance (PM) differ from condition monitoring?
Condition monitoring detects and monitors the wear-and-tear status, whereas predictive maintenance forecasts the putative development of the machine’s future status, and plans the appropriate maintenance work required.
Claudio Geisert, how does PM specifically benefit the owner of machine tools?
Care and maintenance are governed by the condition of the machine. This means the staff concerned carry out precisely the care and maintenance work that is actually required. Effective PM reduces the number of maintenance routines needed, and increases machine availability levels. It also enables line use to be more efficiently planned, because care and maintenance work will now be carried out on pre-specified dates.
One of your specialisms is process monitoring and condition diagnostics: can you give us a highlight from your research work?
Eckhard Hohwieler: For one machinery manufacturer, we have created a tool monitoring feature without any additional sensors or other electronics. A software package integrated into the control system monitors tool wear-and tear and fracturing. On this basis, we developed further algorithms enabling the machine’s condition and behaviour to be checked. This allows an employee to determine weak points with astonishing accuracy using the characteristic values of the drive shafts: even textile flaws in belt drives have been discovered in this way.
Where are the data actually located – at the IPK or the company concerned? Who owns the data, and who is entitled to use them?
Claudio Geisert: The data created during the utilisation phase belong (unless something to the contrary has been contractually agreed) to the operating company. As a rule, the companies concerned will not reveal these data to outsiders, since they fear that sensitive information will be among them, or can be derived from them. One solution commonly adopted is to install an appropriate server inside the company’s own network. This, however, will in its turn deprive the manufacturer of an option for gaining additional insights into the behaviour of his machines in the field. In order to master this problem, a relationship of mutual trust between the manufacturer and the operator is always imperative, though contractual safeguarding for utilisation of the data is indubitably helpful.