TPM companies usually focus on the initial four points, therefore they increase OEE with a fixed average preventive maintenance cost over a period of time. But other companies invest in a computerized maintenance management system (CMMS) to help them efficiently manage maintenance activities.
When an asset is procured, a company does a long-term investment as a fixed cost of asset. There is also an expected cost of maintenance included in the asset's variable cost. Maintenance costs include money spent on both planned and unplanned maintenance work. Yes, accidental breakdowns abruptly increase it [see Figure 1]. As an asset undergoes different types of maintenance activities in its lifetime, its total cost of asset ownership, which includes AMC, also increases.
Figure 1: Maintenance cost reduction over a period of time
All assets have fixed designs when a CMMS system is implemented. A CMMS implementation project does not focus on modifying asset design to optimize its performance and reduce maintenance activities and cost. Rather, this system helps in better management of preventive maintenance activities. This significantly reduces the probability of accidental breakdown events. All breakdown associated costs, including productivity loss, is thus avoided. Here we can say that an asset with a CMMS system can now be operated with a fixed average maintenance cost (see Figure 1).
The real question is, Should we be satisfied with just this one-time reduction in maintenance cost? If a company wants to achieve the next level of maintenance cost reduction, it should reduce maintenance activity itself (see Figure 1). Consequently, maintenance reduction planning can be the way forward and CMMS can be leveraged in this pursuit since companies don't have reliable data that can help them in reducing maintenance activity and associated costs.
Maintenance reduction is a continuous process that focuses on working assets, their spare parts and maintenance costs. CMMS systems can collect maintenance time and cost data at asset or spare parts levels. There are several metrics that can help in maintenance reduction planning.
Average maintenance time (AMT)
A CMMS should be able to record actual maintenance time when a specific planned preventive maintenance activity (PMA) is performed on an asset. Over a period, there will be many times when the same PMA is carried out, but actual time required for this activity may vary. These time data points can be used to calculate simple average maintenance time for an asset's PMA.
Now planning should consider different ways to reduce it. For example, during procurement decision making, only those spare parts that help in reducing AMT should be bought. Collaboration with suppliers is also possible to develop better spare parts.
Average time in between two same unplanned maintenance activities (ATBUM)
With preventive maintenance planning in place, we have constant elapsed time in between two same planned maintenance activities. But there will be accidental breakdowns or unplanned maintenance activities. A CMMS should be able to record the elapsed time in between two similar accidental breakdowns or unplanned maintenances based on which average time can be calculated. Planning should try to increase this by modifying asset design, procuring better spare parts, improving job plans, and implementing better training and skill development.
Daily autonomous maintenance time (DAMT)
For each asset, a CMMS should be able to record DAMT. This data will help in maintenance reduction planning. For example, while procuring the same spare parts, we can compare spare parts from two or more different suppliers and select the one that helps in reducing DAMT. This metric will also help in collaborative research and development of spare parts, which can result in lesser maintenance time.
Average skill cost of maintenance activity
Maintenance activity is carried out either by operators or specialized skilled labor. There is always cost associated with each hour spent by them on maintenance activity. The more skilled labor hours spent, the more the cost associated with maintenance activity. The CMMS should be able to record the asset-wise total skill costs required over a period of time. This cost reduction also should be an aim of maintenance reduction planning.
Skill cost reduction can be possible by the following means:
- Operator's skill sets can be improved so more maintenance activities can be carried out by the operator only.
- Incremental modification in asset or procuring better spare parts so a person with a lesser skill set or a sole operator can maintain it. The lesser skill set person will obviously cost less.
- Improvement in asset or better spare part use so skilled labor requirements can be reduced. This may also help in reducing the time (hr) spent by a skilled person on maintenance activity.
Maintenance common and special cause recording
There are both common (historical and quantifiable variations) and special (unusual, not previously observed, non-quantifiable variation) causes behind maintenance requirements. Maintenance reduction should focus on eliminating common causes, like inappropriate procedures, poor design, ambient temperature and humidity, substandard raw material, etc., and special causes, like power surges, operator absent, broken part, operator falls asleep, etc.
During maintenance activity, if common or special cause is identified, it should be recorded in the CMMS. Root cause and statistical analysis will help in the elimination of common causes, while better job plans (having instructions for avoiding special causes) and training will help eliminate special causes.
Computerized maintenance management systems are helping with end-to-end enterprise asset management. They have been helpful in efficiently and effectively managing preventive maintenance activities, but they should also help in reducing maintenance activities and costs. Gone are the days when information systems were just used to manage information and processes. Now their role is extended to smartly manage the information and help in analytical decision making. A CMMS with maintenance reduction features/metrics will surely reduce costs associated with maintenance activities. This, in turn, will finally reduce an asset's total cost of ownership.
- Wireman, Terry. "Maintenance prevention - the neglected pillar of TPM." 2000, Adams Business Media, Inc. http://vestapartners.com/worxcms_files/MaintenancePrevention.pdf
- Total Productive Maintenance: http://en.wikipedia.org/wiki/Total_productive_maintenance
Devesh Dubey is currently working as a senior associate consultant for Infosys Ltd. His expertise lies in the area of enterprise asset management. He has also played a key role in service request management system design and development.