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Integrating Lean Maintenance with Other Manufacturing Disciplines



You may want to read the introduction to Lean MaintenanceLean Maintenance, Lean Manufacturing, 5S Six Sigma first.

In many plants that follow a maintenance strategy beyond “Fix whatever breaks”, the maintenance plan is integrated with the manufacturing discipline.

Lean Maintenance tries to avoid wasted effort in maintenance by scheduling condition-based maintenance (test or inspect each machine, then schedule maintenance when it begins to show signs of wear). This approach can reduce the waste of storing an excessive inventory of replacement parts for too long, as well as the waste of time to procure out-of-stock replacement parts.

This article deals with integrating Lean Maintenance with other manufacturing disciplines:

5S and Lean Maintenance

 

The 5S methodology uses five principles: Sort, Set in order, Shiny-clean, Standardize clean-up, and Sustain. It is often a first step towards Lean Manufacturing and other production methodologies.

The Sort step divides things into the necessary and the useless or out-dated categories; then it discards the useless things! Replacement parts are included in the search for misplaced or out-dated items. This step also looks to improving safety conditions and identifying deferred maintenance.

The “Set in order” step ensures every item is in the right place: the most-frequently used are stored nearest the point of use. This step also lays out the flow of material for efficient work processes. A clear action item for the maintenance team is to ensure that tools and replacement parts are stored where they are convenient for the tasks. On the other hand, they will probably be stored farther away than the daily production tools. Therefore, clear labeling and a strict discipline of “put it back where it belongs” must be followed.

“Shiny-Clean” is a one-time step to make everything clean and set that as the standard.

Standardized clean-up is the ongoing and regular task of keeping the facility clean to meet the “Shiny-Clean” standard. It should be a five-minute task at the end of each shift, with larger tasks on a schedule. Regular inspection or maintenance of equipment  by the operators can be added to this daily schedule.

The final ‘S’ is “Sustain”. This ingrains the 5S behaviours into the factory’s culture and into the standard working life of each employee.

To some degree, the 5S view of dirt is like the Lean Maintenance view of equipment breakdown. 5S would ask “Why does this area get dirty? What can we change to prevent dirt from building up”? Preventive cleaning is like preventive maintenance: it keeps the problem from occurring.

The 5S program is very useful if dirt, dust or other contaminants lead to equipment breakdown. It is also excellent at ensuring tools are stored in the right places. This can be especially important if maintenance tools have been stored near the maintenance team’s headquarters, rather than in the department where they are used. 5S also helps if rarely-used tools are misplaced or forgotten.

A typically successful 5S program increases overall productivity by about 10%. Several factors come into play:

As well, applying 5S to the maintenance shop affects the productivity of these technicians. It is distracting and counter-productive to leave half-finished repairs sitting on a workbench because replacement parts are not available or not conveniently stored. Either prohibit bringing machines into the maintenance shop unless the replacement parts are available, or store the broken equipment safely out of the way so the technicians can repair items that do have all the parts available.

 

Lean Manufacturing and Lean Maintenance

Lean Manufacturing eliminates wasted activities that add no value for the customer, improves worthwhile activities by eliminating inefficiencies, and smoothes out the workload to eliminate high-speed and high-stress phases.

Are there similarities and synergies between Lean Manufacturing and Lean Maintenance?

The Value of Lean Maintenance for the Customer

 

Does maintenance add value for the customer? In its most direct form, maintenance does not. The customer values the finished product, not the warm and fuzzy feeling that their supplier’s machinery is working smoothly.

However, Lean Maintenance should reduce unscheduled downtime for repairs, leading to on-time production and on-time delivery to customers. Customers do value on-time delivery. One aspect of evaluating a maintenance program is to check for an improvement in customer retention due to timely deliveries.

As well, many machines begin producing defective, or at least, less-than-ideal products, as they near their next maintenance date. Performing maintenance on time, “just” before the machine begins to deviate from its specifications, can lead to lower defect rates and continued high-quality output.

 

Can Lean Maintenance Reduce Inefficiencies in Maintenance Activities?

With a focus on condition-based scheduling for maintenance and a reduction in the need for unscheduled repairs, Lean Maintenance does reduce inefficiencies. Foremost is the fact that unscheduled downtime in a Lean Manufacturing shop affects more than just one machine: downtime can disrupt the whole factory.

When scheduling maintenance, the supervisor can also check and ensure that necessary replacements parts and skilled workers will be available at the scheduled time.

As well, if multiple maintenance operations can be performed during one outage, it can be more efficient than staging multiple disruptions. This is especially true if the same parts must be disassembled each time, and if several people can work on different tasks simultaneously.

 

Can Lean Maintenance Smooth the Maintenance Workload?

This may be the most obvious benefit of scheduled maintenance versus unscheduled repairs. In a repair scenario, everyone feels the pressure to fix the machine so production can resume. The lost productivity is expensive in labour costs at other machines idled by the breakdown. Missed deadlines may disrupt customer relationships and lose future contracts. The pressure can be intense.

Lean Manufacturing recognizes that working at high speeds and under pressure often lead to errors. Lean Maintenance has the goal to make scheduled maintenance about 80% of the crew’s labour time. This does not reach the Lean Manufacturing ideal of smoothly scheduling all work, but it may be a significant improvement over the ratio of maintenance to repair that your factory currently experiences.

 

Lean Manufacturing Fits Well with Lean Maintenance

To conclude, the two “Lean” approaches do work well together. It will not be possible to fully smooth and schedule the maintenance side as completely as the manufacturing. Even if you “overspend” on maintenance, Murphy’s Law will sometimes cause an unexpected breakdown.

However, the corporate culture espoused by “Lean” works well for both the manufacturing and maintenance operations.

Remember that Lean Manufacturing requires reliable machinery to keep the production processes working on time. Lean Manufacturing absolutely cannot succeed if unscheduled repairs cause widespread delays.

Indiscriminant maintenance, meaning “hire more technicians, keep more spare parts, and schedule lots of maintenance”, is an unprofitable response to the need for reliability. A Lean Maintenance program is both effective and cost-effective in improving the reliability of the machines in a Lean Manufacturing environment.

 

Six Sigma and Lean Maintenance

The Six Sigma discipline reduces variation in order to improve quality. A Six Sigma approach to Lean Maintenance uses Six Sigma’s DMAIC project cycle:

One might run a Six Sigma project for Lean Maintenance on one machine at a time, rather than trying to analyze a whole factory.

Defining the problem would then be more specific than simply “unscheduled repairs”. An example of a more focused problem would be “the gears seize up too often; we have to stop and make repairs”.

Measure that specific problem by reviewing the repair and maintenance log for that machine. This may reveal “the gears seize up every two or three months”. Each repair takes about two hours, so lost productivity and direct labour can be calculated easily. Let’s say that parts are not usually damaged on this machine, so replacement parts are not a factor.

Six Sigma has an extensive problem-solving methodology, using principles from statistics to determine the most likely causes. For this example, the analysis shows that the correct lubricant is used. Operating speeds and temperatures are normal until just before the gears seize, at which time it slows down and heats up. The lubricant is much too thick at the time of failure. No excessive wear is found. A lot of dust is in the air around this machine, and settles on everything. The electric power supply is stable and not the problem. The analyst concludes that excess dust is getting into the lubricant.

Further analysis is required to decide on a solution: to spray a liquid to hold down the dust where the material is being cut; fans or blowers; air filters or dust shrouds? Should we simply schedule changing the lubricant every six weeks, or when the temperature rises past a certain point? These theories are tried and tested before deciding on a solution.

At this point, implementing the solution may require changes in the engineering of the equipment or in the behavior of the operator.

Once implemented, the project is not complete until the effects are measured. In this case, does the lubricant remain at the correct viscosity for six months or a year? Do the gears seize up anyway in three months? This controls the process so the outcome is known and verified.

The Six Sigma approach can be overwhelming in the analysis step. However, it works well for difficult problems. It can be time-consuming, especially in the analysis and final control steps.

However, the DMAIC approach, with appropriate quality tools, is effective in solving the widest range of problems. This approach is the ideal standard procedure for troubleshooting and problem solving, regardless of whether the company officially embraces Six Sigma.

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.

Contact Oskar Olofsson



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