What is Lean Maintenance?
Lean manufacturing, lean maintenance, and the whole lean concept have had many successes, but many companies have not achieved the results they expected. There are many reasons why lean maintenance fails, but the number one cause of failure is the lack of focus on reliability. To understand this, we must start by defining lean maintenance.
Lean maintenance is a proactive maintenance operation employing planned and scheduled maintenance activities through total productive maintenance (TPM) practices. It uses maintenance strategies developed through the application of reliability centered maintenance (RCM) decision logic and is practiced by empowered (self-directed) action teams using the 5S process, weekly Kaizen improvement events, and autonomous maintenance. Multi-skilled, technician-performed maintenance is also done through the committed use of a work order system and computer managed maintenance system (CMMS) or enterprise asset management (EAM) system. The team is supported by a distributed, lean maintenance, or maintenance repair organization storeroom that provides parts and materials on a just-in-time (JIT) basis, backed by a maintenance and reliability engineering group that performs root cause failure analysis (RCFA), failed part analysis, maintenance procedure effectiveness analysis, predictive maintenance (PDM) analysis, and trend and analysis of condition monitoring results.
Defining Maintenance and Reliability
The problem most companies have is that they fail to define lean maintenance. In the aforementioned definition, you will find that reliability is a key ingredient in this process. I have always asserted that without reliability, you cannot have maintenance. The two are integral to each other and woven together. Without the two you cannot have capacity.
Let's look at the definitions of maintenance and reliability:
Maintenance: The act of maintaining—to maintain is to keep in existing state.
Reliability: The ability of an item to perform a required function under a stated set of conditions for a stated period of time.
Thus "without maintenance we have no reliability and without reliability, no maintenance," so what are the failures or trip wires, as I call them, that we see in lean maintenance implementation?
- Lack of focus. Ask operations and maintenance the same question: "Where should we focus our efforts to improve operational performance using lean principals?" and you'll get two different answers. If no technical basis is used to assess the potential impact of asset failure, then you'll get a wide range of answers—with no focus on the business impact of the change.
- Lack of understanding of the function of an asset. The required functions and associated performance standards of equipment have never been defined with the reliability approach to capacity, which is the RCM process. In the definition of lean maintenance, you will find RCM as a key component to defining an asset's function and associated performance standards. In other words, we do not know what the requirements are for an asset to provide what a company needs, in order to meet the company's business goals. I have found the common thread among companies that are truly successful is the ability to define the functions and performance standards for key assets. Their reliability programs are focused around the reliability approach to capacity that pays attention the business needs of the company.
- Lack of ownership of asset reliability. When lean is implemented, many times companies don't include the maintenance department, and see this process as a production project only, forgetting all about maintenance until the company needs maintenance's help. I honestly believe that a company should own the reliability of an asset and the maintainability of it as part of a partnership. Maintenance provides the technical resources to ensure the reliability of an asset in order to meet a company's capacity and business goals.
- Time-based preventive maintenance (PM) is used instead of the reliability approach to capacity to focus on what is required for an asset to meet the business goal(s) and what the process will entail. Time-based PMs can cause equipment to be down unnecessarily and failures can be induced by performing intrusive PMs. Many times, maintenance costs are higher than they should be because of time-based PMs.
- Process for the sake of process. Companies focus on changing the maintenance process instead of using the same energy to focus on the reliability needs of the asset. I am not saying you do not need a strong maintenance process, but if you don't understand the reliability needs of an asset enabling it to meet the business goals of an operation, then how do you develop a maintenance process?
The Reliability Approach to Capacity
So what can you do? I recommend that you follow these steps to success. I call this the reliability approach to capacity.
- Perform a risk prioritization analysis of your assets. This process helps the company to focus and get results quickly, which in a lean world, makes good business sense. Asset risk prioritization defines all of your assets in a ranking that is in-line with the business goals of your company, as defined by management. This process allows you to know which assets provide the largest impact to your operation, and allows you to calculate a return on investment as a reliability approach to capacity.
- Take one asset at a time, starting with the assets that have the biggest impact (based on the risk prioritization). Identify the functions of the asset, its performance standards (what we expect an asset to do in its present operating context), what the functional failures are, and what failure modes have occurred which cause the functional failures.
- Identify proactive tasks that need to be taken to identify a potential failure—a reduction of equipment reliability leading to functional failure. Proactive tasks identify the reliability status of an asset in order to induce an activity to restore the reliability of the asset—before a functional failure occurs. Remember a failure is defined as "the inability of an asset to do what its users want it to do". Some of these proactive task are
- Condition-based monitoring. This can be performed with remote devices, handheld devices, or through visual means.
- Predictive maintenance. This includes vibration monitoring, ultrasonic monitoring, infrared monitoring, and others.
- Time-based PMs. Yes, these do have their place, but only after a reliability assessment has identified the need.
- Next you must determine what must be done to the asset to restore reliability, once the equipment is reduced to a point where failure is known to occur in the near future. This can be done through scheduled restoration, or if the consequences of failure are minimal, you may want to operate the asset to failure. Most of the time, this is not an option. If an acceptable proactive task cannot be defined, redesigning or replacing the asset (with new technology) may be required.
- Finally, market the success of this process internally and externally and then continue this process with the next asset, as identified through the risk prioritization analysis.
Warning: If the asset is not maintainable, then restoration must be accomplished. Remember you cannot maintain an asset that is not reliable.
Finally, accomplishing this process will ensure lean maintenance in your organization is successful in the short and long term, and when done properly, it can double or quadruple your return on investment.
About the Author
Ricky Smith, CMRP (certified maintenance and reliability professional), CPMM (certified plant maintenance manager) , has worked in over 400 plants world wide with over 30 years experience in maintenance and reliability as both a practitioner and consultant, author of numerous books that include Lean Maintenance by Elsevier Science Publishing Company.
He is currently employed by Ivara Corporation in Toronto, Canada. Send your e-mails to ricky.smith@Ivara.com