Asset reliability drives Lean maintenance

Lean maintenance is the application of Lean philosophies, methods, tools and techniques to maintenance functions.


Lean maintenance is the application of Lean philosophies, methods, tools and techniques to maintenance functions. It has the same fundamental goals: eliminating wastes associated with labor, inventory, procedures and techniques, resulting in improved productivity and reduced costs.

Lean maintenance is not simply a “slash-and-dash” approach in eliminating jobs and cutting costs. This common approach of slash-and-dash doesn’t eliminate waste or cut costs. Lean maintenance philosophy reduces costs by eliminating wastes that can be defined as “anything that doesn’t add value to the product, process or service.”

Many of the tools used to implement Lean principles for manufacturing also apply to maintenance. They include: 5S, Kaizen, Just-in-Time, elimination of the seven deadly wastes, and so on. However, although this article does not discuss these Lean tools, it does emphasize using a CMMS or EAM as a tool to aid in accomplishing Lean maintenance goals.

Lean maintenance principles

Much has been written about Lean manufacturing principles. Many of them are directly applicable to Lean maintenance, which include:

Work flow %%MDASSML%% One of the common performance metrics is planned vs. unplanned work orders. The benchmark goal has been 90% planned (PM and other planned activities) and 10% unplanned corrective/breakdown maintenance. In reality, with most organizations, the ratio is anywhere from 10% - 30% planned maintenance to 70% - 90% unplanned. This is indicative of operating in a reactive mode, which contributes to waste, reduced equipment life and lost productivity.

A thorough understanding and analysis of maintenance work process flow makes it easier to identify and eliminate waste. The goal is not only to eliminate waste, but to develop an improved work process flow that is more effective and productive. As the flow is thoroughly reviewed and analyzed, the entire process flow becomes visible. Wasteful activities such as delays and unnecessary travel are easily identified (Fig. 1).

A typical maintenance work process flow can point out wasteful activities, which include:

  • Overproduction %%MDASSML%% In the maintenance environment, overproduction is doing any work that does not add value. Performing preventive and predictive maintenance tasks more often than is necessary and redoing jobs that were not done correctly the first time are examples

  • Waiting %%MDASSML%% Areas of wastes in this category include maintenance personnel waiting for equipment availability, job assignments, tools, parts, instructions, other crafts, permit approval, etc. Waiting is not a value-added activity and should be eliminated or reduced as much as possible

  • Transportation %%MDASSML%% Unnecessary travel is the result of ineffective planning and scheduling. Examples include traveling to the maintenance shop to get technical information (O/M manual, prints, etc.) and traveling to the storeroom for parts and tools. Although not always visible, poorly-designed PM routes also contribute significantly to waste

  • Process waste %%MDASSML%% When performing a breakdown repair, maintenance personnel are typically under tremendous pressure to fix the machine as soon as possible and return it to production. They are not given enough time to fix it properly. This results in poor repairs and recurring problems. Properly performed repairs would eliminate this process waste and save lost production time in the long term. Many organizations use CMMS or EAM systems. Processing wastes also occur when inefficiencies exist in these systems. Examples are poorly designed applications that require multiple entries of the same data, or material requisitioning processes that require redundant approvals

  • Defects %%MDASSML%% In maintenance, a defect can be defined as leaving an asset in an unreliable condition. Causes of defects in the maintenance environment are numerous. Defects due to poor workmanship arise from inadequate training, inadequate/outdated procedures and not having proper tools to do the job. Equipment/asset reliability can minimize defects. Machines that are reliable produce products that are within specification, less scrap and eliminate the cause of defect correction. Equipment must be ready to run when demand is presented

  • Root cause %%MDASSML%% Although breakdowns and failures are never planned, they still cause the loss of production and money. Finding the root cause of a failure provides an organization with a solvable problem. Once the root cause is identified, a fix can be developed and implemented, which %%MDASSML%% if properly documented %%MDASSML%% can prevent a recurring failure situation

  • Parts inventory %%MDASSML%% Examples of wastes in spare parts inventory management are obsolete inventory, excessive inventory and inadequate PM programs. Most storerooms contain a significant amount of obsolete inventory, which ties up capital and consumes management resources. It can easily amount to 10% to 20% of annual inventory dollars. Excessive inventory is not obsolete, but it is inventory maintained at unnecessarily high levels, also tying up capital and consuming management resources. Inadequate PM programs cause equipment failures, which in turn result in additional parts requirements (consuming working capital) and downtime.