Preventing unplanned downtime

Published:  11 December, 2015

PWE takes a look at how condition monitoring of fan units prevents unplanned downtime at a thermal paper plant. Whether it’s for receipts, ATM machine bank statements or tickets – thermal printer paper is all around us. The paper’s special properties are due to a coating that is applied to the surface of the paper.

At Mitsubishi HiTec Paper Europe GmbH (MPEB) in Bielefeld, Germany, coating machine 3 applies a coating to around 300 tonnes of thermal paper each day. 26 fan units ensure that coated paper is dried without being touched. Since 2014, 26 FAG SmartCheck systems from Schaeffler have been monitoring these fans for any signs of abnormal vibration. The systems are helping to prevent unplanned machine downtime, optimise production and reduce the total cost of ownership.

Monitoring bearings and processes

The 26 fan units on coating machine 3 at MPEB comprise of air supply fans with a diameter of over one metre that weigh around 100kg, as well as smaller, lighter extraction fans. Due to fan speeds of 1500rpm and the weight of the fans, over time, the units become subject to imbalance, which directly affects the bearings. If this imbalance is not detected and eliminated quickly, the result is process downtime and a reduction in plant production capacity.

This is precisely what happened in mid-2013. One fan on coating machine 3 stopped working due to imbalance, which wasn’t detected quickly enough. As a result, the bearing and adjacent components were badly damaged. A sudden, unexpected stoppage occurred, which led to a reduction in production rates.

To solve this problem, MPEB installed 26 FAG SmartCheck condition monitoring systems on each fan unit. Using a simple ‘traffic light’ warning system on a status display, FAG SmartCheck provides early indications if limit values are exceeded, which prevents bearing failures and any associated machine downtime. If imbalance is detected that is outside the ‘normal’ pre-set limits, the status display changes from green to yellow. However, the system can still continue in normal operation. A red warning indicates that action must be taken immediately. An integrated web server enables operators to access each individual sensor and view detailed condition monitoring data.

The project was implemented in conjunction with Werthenbach, one of Schaeffler’s authorised distribution partners in Germany, with technical capability in condition monitoring. If necessary, Werthenbach engineers forward information from the sensors to specialists at Schaeffler for analysis. These specialists not only diagnose what the problem is, but also recommend what remedial action should be taken. As FAG SmartCheck displays an initial yellow warning up to three months in advance, this provides plant operators and maintenance teams with sufficient time to order any replacement parts and to plan a convenient time to carry out fan repairs or maintenance – preventing any unforeseen production downtime.

In addition to monitoring bearings, the solution also enables ‘total process monitoring’. One FAG SmartCheck system monitors vibrations in one fan unit. However, both the plummer block housing unit and the fan impeller each has its own particular vibration pattern/signature. Using historical condition monitoring data, trend curves can be created, which are used as a basis for drawing conclusions about the condition of the machine and the processes. This means it is often possible to detect when and why a particular problem has occurred so that it can be permanently eliminated. Based on this reliable CM data, MPEB can now track the behaviour of its machines over the long term under constantly changing manufacturing conditions and then make specific design improvements.

Just a few months after being installed, the monitoring system demonstrated its capabilities by identifying irregularities in two of the exhaust air flotation dryers. Werthenbach’s servicing team recorded the data and carried out an initial analysis. Experts from Schaeffler then produced a report outlining the results of this analysis and a recommended action plan. The irregularities were caused by impermissible high imbalance and damage to the bearing outer ring. Both problems were resolved quickly during planned maintenance, long before the imbalance became audible or noticeable, and before any damage to the adjacent components could occur. A complex, lengthy and costly investigation of the problem was therefore avoided.

On the strength of these good results delivered by the pilot project, Mitsubishi HiTec Paper Europe has decided to install the FAG SmartCheck system on the coating machine at its Flensburg plant. The 11 air supply fans and 11 extraction fans at Flensburg are now being monitored by 22 FAG SmartCheck systems.

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