Vibration analysis and thermographic surveys

During each visit to the plant, a Schaeffler field service engineer takes vibration measurements to identify any deterioration of rolling bearings and other general mechanical components (e.g. gears, fan blades) on a variety of plant and equipment. This equipment includes small motors, gearboxes, pumps and fans. This equipment drives a variety of plant such as conveyors, peeling machines, cold and hot washers, fryers, slicers, bucket elevators, heat exchangers, extruders and centrifuges.

Vibration measurements are made and stored using Schaeffler’s FAG Detector III handheld vibration monitoring device. With its built-in software, ‘Trendline’, which includes a database of more than 20,000 different bearing products from different suppliers, this device enables the user to collect, store and analyse vibration measurement data. Used in combination with the data viewer, the bearing database is suitable for assessing a machine’s condition. For example, up to four different characteristic values can be stored and displayed against one measurement point (several defect bearing frequencies can be checked efficiently using a single measurement point).

The FAG Detector III is used to measure and record vibration data at each selected measurement position on the monitoring route at the customer’s plant. The three basic measuring parameters are velocity (a measure of overall machine vibration that responds to mechanical issues such as imbalance, misalignment and looseness), acceleration (typically used to monitor gear defects and progressing bearing defects) and enveloped acceleration (a measure of high frequency, impact-type events, typified by early bearing or gear faults).

Measurement data is analysed by the Schaeffler field service engineer, who then writes a report and recommended action list (if required) for the customer. The report typically includes Acceleration and/or Velocity Trend plots that show alarm limits (red and yellow lines) and how the vibration data has varied over time.

David Goves, applications engineer at Schaeffler UK comments: “The alarm limits for the equipment (motors, pumps, fans, etc) are initially set at default values based on ISO recommendations. However, as the database of measurements is built up over time, these alarm limits can be reviewed and may be adjusted to more appropriate levels.”

The FAG Detector III is used to take measurements on each item such as drive motors, gearboxes, pumps, pedestal bearings (housings) and so on. For each piece of equipment included in the agreed patrol monitoring route, velocity measurements are normally taken in the horizontal, vertical and axial planes at the drive end and non drive end of each item. Additionally, acceleration measurements may be taken in the horizontal planes of gearboxes and motors. Furthermore, enveloped acceleration measurements may be taken in the horizontal plane on each item of a piece of equipment. The exact set-up for each piece of equipment may vary depending on its size, accessibility and previous history of issues.

After analysing the recorded vibration data using the FAG Detector III’s Trendline software, Schaeffler is able to report on all the items of equipment and to recommend any repairs or remedial action that is required. If bearing wear is found to be the cause of high vibration levels on a gearbox, for example, this can be reported to the customer, who can then source the appropriate bearings and plan precisely when the maintenance work i.e. replacing the defect bearings, can be carried out without disrupting the rest of the plant.

Thermal imaging

Thermal imaging technology produces fast, accurate results in a real time, high resolution illustration, enabling engineers to detect problems that otherwise may be overlooked. Remedial work can therefore be carried out before system failures or production stoppages occur.

“The great advantage with using thermal imaging technology is that it is non-invasive and can detect hot areas, enabling us to evaluate the condition of electrical components inside panels and control cabinets, and whether potential problems are likely to occur,” explains Goves.

At the crisp production plant, a Schaeffler field service engineer normally conducts a site survey of electrical panels and control cabinets using a handheld thermography camera, which incorporates a built-in digital camera and customised reporting software. Equipment checked includes fuses, switchgear, wiring and cabling. “We can quickly open a cabinet and sweep the electrical components inside for any hotspots. If we do find any hotspots, these are often caused by loose wiring or cabling, a defective fuse or the fault could be due to some faulty equipment further down the line. The important thing is that we report the fault and the customer can then check it immediately before any line stoppages occur,” says Goves.