FEATURE TEST & MEASUREMENT A
t the Mitsubishi HiTec Paper Europe plant in Bielefeld, Germany (MPEB),
around 300 tonnes of thermal paper – which is typically used for sales receipts and tickets – goes through one of the coating machines each day. On Coating Machine 3, the raw paper is finished with a pre-coat and top coat to give it its thermal characteristics. So, to guarantee the perfect coating, the paper, which can be up to 2.9m wide, must be dried without contact. With an operating speed up to
1730m/min, the four-story coating machine features 26 fan units for contactless drying of the coated paper. The air supply fans blow hot air at up to 250˚C into the drying hoods. However, the surface of the thermal paper must not be heated above 68˚C or discolouration will occur. The fans have a diameter of just over
1m and weigh around 100kg, while the exhaust air fans are slightly smaller and lighter. As the fan rotates at 1500rpm, there can be a slight imbalance, which can result in the bearings wearing prematurely. In fact three years ago an imbalance on the machine was not detected in time, resulting in fan failure and damage to the bearing and attachment parts – and leading to a system shutdown. The company therefore decided that condition- oriented maintenance was needed.
MEASURING THE VIBRATION To help, 26 FAG SmartCheck sensors from Schaeffler now monitor the fans by carrying out vibration measurements. A FAG SmartController – based on a Mitsubishi Electric PLC from the MELSEC L-series – operates as a bidirectional gateway between the controller and sensors. FAG SmartCheck systems have a status
indicator based on a traffic light system. If the status changes from green to yellow (preliminary-alarm status), a predefined limit value has been exceeded, but the machine can still continue to operate for the time being. A red alarm indicates an urgent need for action. The operator can access each individual sensor via an integrated web server and display detailed information. Of benefit, the system can issue an initial warning via the yellow preliminary alarm up to three months in advance, leaving sufficient time to schedule a system shutdown and order replacement parts. The new solution was put into action
six months after the problem was discovered, with the contract awarded to Werthenbach, the company responsible for the development and implementation of the FAG SmartCheck condition monitoring system. With support from
44 NOVEMBER 2016 | INSTRUMENTATION Good vibrations
Vibration measurement is being used to monitor the condition of a machine designed to coat thermal paper, helping to prevent equipment failure
Mitsubishi Electric Europe, the network communication – the actual integration of the comprehensive monitoring system into the customer’s system - only took a few hours. Power-over-Ethernet (PoE) meant that the number of cables could be reduced by two thirds. Thomas Schmitz, service manager condition monitoring at Schaeffler, commented: “Each FAG SmartCheck system monitors a fan unit for unacceptable vibrations and the two pedestal bearings and the fan impellers each have their own vibration pattern. Based on the data history, trend curves can be produced and used as a basis for drawing conclusions regarding the condition of the machine and processes. So it is often possible to identify when and why a problem first arose so that the root cause can then be addressed. Based on meaningful data, MPEB is able to track the long-term behaviour of the units despite constantly changing production conditions and to carry out targeted structural improvements.”
A SUCCESS STORY Just a few months after commissioning, the monitoring system detected anomalies in two exhaust air flotation driers. The Werthenbach service team recorded data and carried out an initial analysis. The experts from Schaeffler went one step further and compiled the results, along with a recommended action plan. The cause was high imbalance combined
with damage to an outer ring bearing. Both problems were successfully resolved in good time by carrying out scheduled maintenance, long before the imbalance would have become audible or perceptible, or before damage may have been caused to adjacent components.
On Coating Machine 3, the operator can access each individual sensor via an integrated web server and display detailed information. Of benefit, the system can issue an initial warning via the yellow preliminary alarm up to three months in advance, leaving sufficient time to schedule a system shutdown and order replacement parts
As an intelligent gateway between the controller and sensors, the FAG SmartController transmits vibration data and status information from those sensors to the controller, where the data can then be displayed in a SCADA system. It is connected to the FAG SmartCheck as well as the controller via the Ethernet cable by means of PoE switches. The SmartController also distributes individual variable speed-related information from the controller to the individual sensors. Schaeffler is now a Mitsubishi Electric
e-F@ctory Alliance partner. The MELSEC L-series controllers can communicate with all common fieldbus systems and at the control and sensor level via an Ethernet based connection. The SLMP protocol (Seamless Message Protocol) running between sensor and controller is based on Ethernet TCP/IP and therefore permits system access via an integrated web browser in the sensor at the same time, as well as bidirectional data communication with the controller. The whole setup is freely expandable.
In the future, it is envisaged that the whole machine will be monitored by a unified system, enabling the behaviour of all the rotating parts to be precisely recorded if the speed is changed. The ultimate aim is for MPEB’s own technical and operating personnel to build up their knowledge of the monitoring system, so that they will then be able to look after the system themselves. Following this project, Mitsubishi
HiTec Paper Europe has also decided to install the FAG SmartCheck on the coating machine at its Flensburg site.
Mitsubishi Electric Europe T: 01707 288769
Gb3a.mitsubishielectric.com
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