Lean Six Sigma

Lean vs. Lean Maintenance

The recent popularity in lean manufacturing has spilled over into the maintenance world, with more and more organizations attempting to apply the principles of lean to their asset management departments. But it isn't that simple, says Reliability Expert Daryl Mather. He explains which principles apply and which don't in his latest Web column.

By Daryl Mather

During the past decade, the “LEAN” phenomenon has allowed manufacturing industries to greatly increase their levels of profitability and productivity. Combined with other initiatives, such as TPM, LEAN has allowed these companies to focus on the efficiency of their production processes.

The Merriam-Webster online dictionary defines efficient as being “productive without waste.” Recently, we have seen many consultancies and companies starting to talk about terms such as “LEAN Maintenance,” an attempt to bring the same efficiency improvement approach into the world of physical asset management.

The thinking behind this is laudable, and many companies have been able to benefit greatly from the waste elimination focus that LEAN fosters.

The problem is that the same fundamental principles have been bought directly from the production environment into the asset maintenance environment. The same seven areas of waste, the same initiatives such as just-in-time inventory management, and the same sort of focus on the day-to-day without including a longer term focus.

(In the most extreme cases it appears as if LEAN seems to be a metaphor for every buzz word and service that a consultancy has to offer – but that would be cynical)

“So what?” you say. “Why should maintenance be any different?”

The reason why a lean maintenance approach cannot just be a mirror image of a lean production approach is because the business dynamics of asset maintenance and those of production are fundamentally different.

A short summary of the differences is below, but in my new book, tentatively titled Asset Resource Planning: Lean Strategies for Efficient Maintenance, this is explained in a lot more detail.

  1. Production plans are driven by sales forecasts and in the near term by sales orders. This means they are driven by an exact schedule of works. Asset maintenance, on the other hand, is driven in part by a schedule of routine work and in part by the likelihood of failure of the assets under management.  This means that initiatives such as JIT inventory management have only a limited ability to assist the efficiency of the maintenance process. Issues such as just-in-case inventory management are far more important.  This has implications not only within the area of operations, but throughout the entire supply chain. Often the improvement of a supply chain is based on “how we buy,” the probabilistic nature of asset maintenance means also that we need to be thinking about “why we buy.”
  2. Production efficiency is gained almost entirely through present operations. So to be “productive without waste” is thought of in terms of the day-to-day activities involved in managing the production processes (And rightly so).  Asset maintenance being “productive without waste” has an additional time perspective. A large part of any asset maintenance spent over time relates to asset replacement and refurbishment intervals. Depending on the type of plant these are often very large scale costs on par with the initial equipment purchase in terms of magnitude.  So “productive without waste” means not replacing these too early, and often in not allowing them to fail completely before replacement. In order to be truly efficient we need to control a range of issues related to asset use, type, expected life and other issues. This is significant and reaches outside of the maintenance function itself. For example – a machine that is subject to regular overload situations is likely to have a shortened life expectancy, meaning that capital will need to be spent on it at an earlier stage than previously thought.
  3. The last issue we will explore here is that of data management and collection. Improvement of production processes can often be made through recording and acting upon dynamic operational information.Data management and collection is also useful in asset maintenance but we also need to be able to confidently forecast spending in the future and how that is affected by current activities.

This requires data other than the dynamic operational data. It also requires static data on equipment type, location and age; as well as a range of data regarding failure rates, asset condition and other areas.

While this seems straight forward, when this task is not correctly managed it can be a tremendous strain on the resources of the asset maintenance department.

So where does this leave us? If we believe firmly, as I do, that LEAN maintenance needs a different focus than that of LEAN production, what should it be?

I have put together a list of eight areas where the majority of waste in maintenance occurs.
While some of these are the same as those in a standard LEAN approach, there are some notable differences. Some items have been deleted from the list of wasteful activities, while others have been added.

  1. Unproductive work – Efficiently doing work that doesn’t need to be done!
  2. Delays in motion – Waiting times, delays waiting for parts, machinery, people, etc.
  3. Unnecessary motion – Unneeded travel, trips to tool stores or workshops, looking for items, moving mobile work stations around without good reason.
  4. Poor management of inventory – Not able to have the right parts at the right time. A complex area that can cause many of the other areas of waste on this list.
  5. Rework – Having to repeat tasks, or do additional tasks, as a result of poor workmanship.
  6. Underutilization of people – Using people to the limits of their qualifications, not to the limits of their abilities!
  7. Ineffective data management – Collecting data that is of no use, or failure to collect data which is vital.
  8. Misapplication of machinery – Incorrect operation or deliberate operational strategies leading to maintenance work being done when it needn’t be.

If we really want to deliver “productivity without waste,” or efficiency, in asset maintenance, then we need a different version of LEAN; one that takes into account the unique business dynamics of the area that we work in.