Equipment breakdowns and reactive downtime are a fact of life for every mine. The overarching reason for breakdowns is a failure to take ownership and care of the assets and servicing quality is critical.
In this article, we’ll discuss two aspects of service sheet execution quality—The service sheets themselves and their execution even if they are not perfect. The good news is these problems can be solved with a proper culture.
Problem #1: Service sheets can be setup to enable people to work in a scheduled manner
For example, a truck service sheet may say brake pads must be replaced when they’re under 20 millimeters thick. I have seen instances where brake pads were recorded on the service sheet as being 20.1 millimeters thick and no one did anything because it was above the limit. At the next service, however, the machine came in with brake pads that were under specification and people had to scramble to find labour and parts. It became a reactive job for them and created more unscheduled downtime.
Solution #1: Set limits for immediate action and for limits for scheduling
A solution is to set limits for scheduling work and limits for immediate action.
Keep 20 millimeters as the limit for an immediate break-pad change but establish 21 millimeters as the threshold for when brake pads must be scheduled for the next service. The brake pads will be below 20 millimeters by then, and if the work on them is scheduled, you avoid unscheduled downtime and reactive work.
Eventually tablet-based service sheets programmed to automatically raise the subsequent work orders when the limits are reached will solve this problem. These are emerging but there is a large task still to be done in order to get the data into these systems.
Problem #2: Maintainers want perfect service sheets
Although you want service sheets that set up mechanics to work in a scheduled fashion, you can’t have a perfect service sheet. You still need people on the floor to use critical thinking and consider what’s best to do in a situation.
If brake pads get down to 20.1 millimeters and inspectors know the limit is 20 millimeters, they should be able to deduce that it should be scheduled now because the pads will be below the limit by the next service.
The airline industry has highly detailed service sheets.
For example, when checking leaks, inspectors are asked to count the number of drips per minute and compare the result to acceptable limits. Airlines also require general-area inspections that look for other defects not specifically documented on the service sheet. These general-area examinations work because the inspectors take responsibility and have a sense of ownership of the equipment.
When you don’t have that sense of ownership and inspectors are only checking boxes on their sheet, critical thinking goes out the window and problems are overlooked.
Solution #2: Cultivate an environment of critical thinking
Maintenance managers should always try to improve their service sheets, but they also must cultivate an environment where people take care and look for other problems.
Service sheets are developed with the assumption that the equipment will work in certain conditions and will be operated in certain ways. However, inspectors may find that the equipment is not being used correctly or is operated under the wrong conditions, and it is their responsibility to look for the unexpected consequences.
For example, if you have a car with a slide-out drink holder, the expectation is that people will slide that out, put their drink in it, and push it back in when they’re done. The maintenance program for the car might not check the drink holder for ten years if it’s used in this way. However, if someone uses the drink holder as a footrest, it will show signs of wear sooner, so whoever is maintaining that car needs to look for that.
An example from the mining industry is the loading arms of a wheel loader.
These arms are designed so a loader can approach loose material with the front of the bucket. The arms are designed to last the full life of the machine, so the service sheet may only call for an annual inspection of the arms.
However, some operations use a wheel loader on material that hasn’t been adequately blasted. When the operator approaches the material at an angle with the corner tip of the bucket, the action places unanticipated stress on the arms.
That kind of stress causes the arms to crack. Mechanics must be on the lookout for other defects that are occurring and examine the areas of the machine with a critical eye looking for signs of deterioration.
Gerard Wood is one of the mining industry’s foremost authorities on proper mining equipment maintenance. In his long career, Wood has been all over the world, working his way up from an electrician’s apprentice to a maintenance manager with advanced degrees in electrical engineering and business. As managing director for Bluefield AMS, Wood helps the world’s largest mining companies keep their machines running with a simple, practical approach that saves money and improves equipment reliability.