Cement maker set on on-line CM

London -- Online condition monitoring has enabled cement manufacturer Spenner Zement to avoid unplanned downtime and costly repairs to transmission gears and gearboxes at its cement mill in Erwitte, Germany.

Spenner Zement produces a range of cement, lime and dry mortar products. The company also develops disposal concepts for different industry sectors whose waste products can be used for secondary raw materials and fuel.

Spenner had previously experienced major production problems at one of the cement mills at Erwitte, including a three-week shutdown due to damage to a gearbox that was driving the mill. The three-stage gearbox was being monitored by a temperature sensor, which failed to give Spenner’s maintenance team enough warning of damage to the gearbox.

The gearbox damage and subsequent failure not only resulted in weeks of unplanned downtime on the tube mill, but also resulted in costly repairs, which included a completely new shaft and refurbishment of parts of the gearbox housing.

Spenner called in FAG Industrial Services, the maintenance and condition monitoring arm of the Schaeffler Group, to help eliminate any future unplanned stoppages to its tube mill.

FAG recommended its online vibration monitoring system, FAG Dtect X1, along with four, permanently-installed sensors positioned on the main gearbox and reduction gear. Three sensors were installed on the main gearbox to monitor the gear bearings and gear mesh, with one sensor installed at the reduction gear to monitor gear rim and pinion condition.

FAG also provided three months’ vibration monitoring training. Spenner maintenance engineers were trained to analyse the condition monitoring data and are now capable of monitoring and analysing the data on their own.

Around 18 months after its installation the new condition monitoring system detected damage to the gear teeth in the gear mesh. Initially, yellow alarms were displayed on the system, followed by temporary red alarms, indicating potential serious damage.

Visual inspection from Spenner engineers confirmed that tooth damage had occurred in the second stage gears. The gearbox was subsequently replaced during the next scheduled shutdown period, without causing any disruption to production. Had the tooth damage been left undetected, damage to other parts of the gearbox may have occurred, causing costly repairs and further delays to production.

Spenner has since equipped another two of its cement tube mills at Erwitte with the FAG systems. Five sensors are installed on each system, with three monitoring the vibration on the rolling bearings and the gear teeth. The other two sensors monitor vibration at the reduction gear bearings, girth gear and pinion.

All data is transmitted directly to Spenner’s central control room at the plant, automatically triggering an alarm if deviations from pre-set parameters are detected. When initial signs of complex problems are detected, data can also be emailed direct to FAG to carry out in-depth analysis on the data and recommend the appropriate action to be taken.