It is common in the mining industry for people to use a maintenance labour ratio per service meter unit (SMU) or operated hours, when estimating the maintenance labour resources required for maintaining mobile mining equipment. The OEM’s provide benchmarks of maintenance labour per SMU and other companies have their own benchmarks for the different type of equipment. The benchmarks can be easily built from a zero base of tasks with man hours required.
This approach works ok for setting up a new business and defining the required maintenance team to support the fleet. However, there are some limitations with this method for estimating maintenance labour resources when an existing business wants to review their current resources and reset the team to an appropriate level to improve and to manage the tasks at hand. These limitations are as follows:
The benchmark ratios do not account for the site specific efficiencies and effectiveness
If you base the maintenance resources required on the SMU the calculation will say that you need more people as you improve reliability and the SMU goes up. Ie as you improve you need more people. In reality as you improve reliability and availability you can reduce the size of the team. Additional resources are usually only required to get over the improvement hurdle.
As an alternative approach and to overcome these limitations Bluefield has developed an approach to estimating the required maintenance labour based on the equipment downtime. Ie. We know the scheduled and unscheduled downtime and we know how many people on average we put on these downtime events so we can calculate the required workforce using this approach. We also include a method to account for absenteeism and training etc.
Effectively this method provides a maintenance ratio per maintenance hour (scheduled and unscheduled). The calculations will indicate, when a site is in reactive mode and there are availabilities lower than 80%, there is a large resource need. Subsequently, once we overcome these effectiveness problems (see https://bluefield.com.au/2018/03/14/quality-maintenance-execution-standards/ ) and enter the adjusted assumptions for availability, the estimating model will show the actual resources required under a planned, scheduled or proactive maintenance environment.
Of course after estimating the labour requirements there is a need to balance labour types across shift structures but this is a topic for another discussion.
We have provided a simple example of this method for estimating the maintenance labour required. To download the excel file Click Here