Lean Maintenance Calculators
A collection of our most popular calculators in Excel format for off-line use

The Essentials of Lean Maintenance

Lean Maintenance is a key ingredient to a successful Lean Manufacturing environment.

You may want to read the introduction to Lean Maintenance first.

Like Lean Manufacturing, Lean Maintenance seeks to avoid waste:

Wasted maintenance activities that do not contribute to improving the availability of a machine
Inefficient maintenance activities that should be performed more quickly or cheaply
Sporadic maintenance efforts, such as frantic repair work when a critical machine breaks down

Wasted “activity” includes having expensive replacement parts in inventory longer than was necessary; ideally these should be ordered “just in time” for scheduled maintenance.

Inefficient activities may refer to delays while performing maintenance, such as chasing around for tools or replacement parts. Another type of inefficiency comes with poor scheduling: an example is replacing two parts on two separate occasions, when both tasks could have been done during the same outage.

Ideally the maintenance team, like the production operators, should work at a steady pace that is productive but not rushed. A repair crew is more likely to make mistakes when the pressure is on to fix a machine and get the factory back into production.

Generally consultants advise integrating Lean Maintenance with the production disciplines, such as Six Sigma or 5S, already implemented in your factory.

However, this article provides advice on what any Lean Maintenance program needs and should accomplish. It is possible, in fact, to implement Lean Maintenance without formally adopting any of the other disciplines. Some industries, such as mining and pulp-and-paper, have serious maintenance requirements and may be actively seeking ways to improve. In many other industries, maintenance is not often management’s first area of concern when looking to improve productivity and profitability. Even so, inefficient maintenance is expensive and unscheduled breakdowns are even more costly: it may be very worthwhile to investigate what Lean Maintenance can do for your factory.

What Every Lean Maintenance Program Needs

Every Lean Maintenance Program needs:

Information
Goals
Implementation
Evaluation

Here are more details on these requirements:

Information

This may be the largest hurdle in planning a Lean Maintenance program. To address the needs of the factory, you need an inventory of each machine. For each, you need to know:

The manufacturer’s recommended maintenance schedule
History of actual maintenance activities
History of past breakdowns and repairs
Knowledge of the key components to test for “condition-based” maintenance planning

All this information includes both labour and parts requirements.

Goals

The ultimate goal for Lean Maintenance is to minimize the cost of performing preventive maintenance while also minimizing the risk of an unscheduled breakdown. The cost of maintaining one machine is usually much less than the cost of its breakdown, because that might shut down operations altogether.

The usual goals for scheduling the maintenance crew are:

Allocate 80% of time to scheduled maintenance; allow 20% for unscheduled repairs or maintenance that takes longer than scheduled
Of that 80%, gradually increase the time spent training production operators to do routine maintenance, and in monitoring their efforts; then increase the percentage for the most highly skilled maintenance work
Expect that 90% of the activities, or work orders, are for maintenance

The goals for containing costs in spare-parts inventory are:

Do not run out of critical replacement parts
Gradually decrease the time standard replacement parts are in inventory

Critical replacement parts are those that are necessary for a machine to operate, and have a long lead time for purchasing. These are too expensive to keep in stock, but highly valuable in that they are needed to keep the machine running.

On the other hand, the Lean Manufacturing approach is to procure raw materials “just in time” for production. The same principle should apply to replacement parts: purchase them “just in time” for the next maintenance activity, rather than just after the last one.

This drives the need for accurate historical information on the intervals between failures of a critical replacement part.

Implementation

Make a separate plan for maintaining each model of machine. You may need to engage experts to analyze the stresses and causes of each machine’s past failures, and the values of the components to test for “condition-based” maintenance planning.

Part of the process is to meticulously log the maintenance and repair history.

Applying root-cause analysis to every failure (or every need for maintenance under condition-based maintenance) should lead to important clues for extending the useful life of the machine. As an example: let’s say that lubricating oil begins to break down, triggering an oil change as maintenance. Why is the oil breaking down? Let’s say it is dust getting past a filter. The long-term solution is either to replace the filter more frequently or to find another way to prevent dust from getting there (by adding a fan to blow the particulates in a different direction or by adding a filter to trap dust where material is being cut).

Evaluation

As you acquire data, you need to evaluate the effectiveness of the Lean Maintenance program, by comparing various metrics between the “before” and “after” time periods:

Hours of unscheduled downtime per month
Cost of unscheduled downtime per month, as lost productivity
Labour cost of planning and scheduling maintenance activities
Labour cost of testing
Labour cost of scheduled maintenance
Labour cost of unscheduled repairs
Cost of materials for testing, maintenance and repairs

Of course, you will add the cost of planning and implementing Lean Maintenance to the “cost” ledger.

Most factories see a significant reduction in overall cost, because unscheduled repairs are extremely expensive due to lost productivity.

The next article covers the evaluation process in more detail.

Oskar Olofsson, 2011

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I am a Swedish-based Lean consultant, and the owner of the World-Class-Manufacturing.com web site.

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