Condition monitoring explained

THERE’S more to maintenance underground than roller greasing, bit changes and fixing belt splices. Western-based Monitek takes it to a completely new level through its specialization in condition monitoring utilizing vibration monitoring and oil and grease analysis.

Donna Schmidt

Published in the May 2007 American Longwall Magazine

The trend, according to company president Ross Mackellar, is that mine maintenance managers are changing their focus towards reducing risks associated with reliable machinery operation, and employing practices that will make it run more reliably and more safely and ensure the machinery achieves its design life.

Furthermore, Mackellar added, the role of the maintenance manager is to ensure the design level of reliability is being realized, and condition monitoring can make a very significant contribution to this objective.

For such a practice to be successful, however, a mine must observe and heed the necessary protocols of maintenance 100%. “There are some mines who don’t even use oil sampling [on their machines],” Mackellar said, which can be a recipe for disaster and makes premature failure of components a near certainty.

Also vital to consider are associated safety issues and assessment of the unit’s reliability, with the former requiring an immediate response. “If safety issues exist, they should be resolved ASAP,” he said.

Currently, most operations look at two priorities when it comes to mining their coal, which thus have an impact on decision making: keeping production downtime at a minimum and keeping the short-term cost of running equipment as low as possible. That’s not where the considerations should end, according to Mackellar.

When an asset’s value is consumed to the point where the asset can no longer reliably fulfill its function, due to reduction in maintenance activity to achieve short-term financial savings, the financial cost to return the asset to its designed level of reliability is much greater than the perceived short-term savings.

Numerous examples exist where condition monitoring techniques can directly contribute to the achievement of design level of reliability in equipment and provide significant financial savings, according to Mackellar.

“One example which stands out is the savings a southern Illinois underground coal mine made when it installed permanent online vibration monitoring of its mine vent fans,” he said. The vent fans were initially installed with sensors, which detected overall vibration levels.

The primary objective of these sensors was to protect against fan out-of-balance conditions; however, with the introduction of permanent online vibration monitoring, which included techniques to provide early detection of fan and drive motor bearing defects, the bearings could be replaced during scheduled vent fan outages and not during unscheduled breakdowns. The unscheduled failure is very expensive in financial terms due to lost production associated with the inevitable mine evacuation, and consequential vent fan damage.

When Monitek is retained to perform condition monitoring services at an operation, the primary goal is to provide the client with a comprehensive report containing recommendations on how the mine can achieve the design level of reliability from its assets.

Additionally, Monitek can not only diagnose vibration issues, but also train mine representatives in the strategies needed to continue the vibration monitoring process on their own. While most of its business is as a service provider, Mackellar said, the company also serves as a vibration monitoring/analysis hardware distributor for many of its clients throughout the US.

“Monitek’s goal is to continue to provide solutions to our clients’ predictive maintenance requirements utilizing the latest technology at the lowest cost.”