Maintenance in the Lean World

As more and more companies turn to Lean manufacturing to remain competitive, the role of mainte- nance can become somewhat confusing. Our introductory Lean Maintenance column (MRO, Feb. 2004, page 22) explained what Lean meant to the operations group; in this article we expand the principles to the maintenance group.

There are two main issues we need to deal with:

Maintenance in the Lean process, and

The Lean process in maintenance.

The first and easiest question to answer is: How does maintenance fit in a Lean Manufacturing organization?

The world class benchmark of 85% Overall Equipment Efficiency (OEE) may no longer be good enough. For those who progress to Six Sigma as their statistical control, it definitely will not.

This makes it critical that the correct maintenance strategies be employed for each piece of equipment. Unnecessary PMs must be eliminated and wherever possible replaced by non-intrusive predictive techniques.

Anything less than “return to new condition” repairs cannot be tolerated. The sometimes hidden “functional failures” have to recognized and monitored as the Lean process does not allow for the buffer of carrying substantial “work in progress” or the storing of a supply of finished goods inventory.

For those maintenance groups that have existed within forward-thinking organizations, all of this may already be in place, but as more companies move to Lean, there will inevitably be maintenance groups facing these issues for the first time.

There are many companies in the marketplace offering reliability improvements through the use of their patented systems, but beware — unless you make cookies you don’t want to use a cookie-cutter approach. Trying to fit your maintenance group into an existing strategy is a sure way to fail.

If you need to use outside resources to help you develop and implement a strategy, make sure they understand the culture, risk tolerance and spending history of the company. This will ensure they help you develop a strategy that will work for you.

Simply put, Lean Manufacturing is based on the premise that equipment is available when needed, running with no speed restrictions and producing a quality product every time — and it is maintenance’s role is to ensure this.

The second question to answer is: How can we apply the principles of Lean thinking in the maintenance process?

As companies kick off the Lean process, there will be meetings and training to inform everyone about the principles and tools of Lean. They will almost inevitably be focused on the manufacturing process, its administration and its support.

It can be hoped that the maintenance group will be involved in these meetings and their focus can be on how to implement the Lean principles in the maintenance process. This gives a common language to the maintenance group as it demonstrates its support for the newfound company philosophy. It also helps when trying to purchase equipment, tools or techniques to be able to show which of the principles of Lean they support.

The basic principles of Lean are:

Identify what “value” is to your customer

Value Stream Mapping

Make the process flow

PULL from the customer

Seek perfection.

In the maintenance process, these Lean principles can be used to improve efficiency within the department. Here are some examples.

Identifying value to your customer involves sitting down with the production group and setting priorities. Obviously uptime and repeatability are high priorities, but don’t forget safety and environmental impact.

Depending on the piece of equipment the amount of “value ” can vary. “Red Line” or critical equipment are the items of most value to the group. Highlighting the equipment, which if it fails has the ability to shut down the whole plant, is the first priority. Then you work your way down to the lowest priority.

Value Stream Mapping involves looking at the maintenance tactics used first on the “highest value” equipment and again, making your way down to the lowest value items.

Consider whether preventive maintenance (PM) is the way to go — changing bearings, etc., on a frequency basis means shutting down equipment on a frequency basis. Could this frequency be extended by using ultrasonic, vibration analysis or (if oil lubricated), oil analysis — or even a combination of all three.

By examining all maintenance tasks, you can modify them or eliminate the “non value-added” and thereby add “value” to the maintenance role.

Making the process flow entails the planning and scheduling of work. Once a need for work has been established through a work request, getting the work completed as quickly as possible becomes the goal.

Some of the “non-value” activities include looking for parts, parts that need to be modified to fit, machines not being available, or a bureaucratic approval system. These need to be eliminated so the ideal system exists — and it can!

I have visited plants where operators enter work requests on the CMMS, the tradesman then approves or denies the request, and a work order is originated that lists all spare parts and their locations.

The work order also is automatically communicated to the ERP (Enterprise Resource Planning) system and the production scheduler enters it into the production schedule at the earliest opportunity. Copies of the work orders are also forwarded to the central stores where the required parts are placed in a “job bin” with a copy of the work order attached.

For most plants, this is like Utopia. But if you’re going to set goals, why not these?

Another example of making the process flow is to use Total Productive Maintenance (TPM), but as this method (incorporating operator maintenance) involves other departments, it will be dealt with in a future article.

PULL from the customer is the result of a combination of the first three principles. It does, however, require a greater awareness of the maintenance process, and the strategies and techniques available in the non-maintenance group.

Training in and knowledge of these strategies and techniques will allow those groups to make better-informed decisions on when and what to PULL.

The definition of PULL is delivering what the customer wants when the customer wants it, initiated by a customer request and not by forward forecasting. Examples of this could be the total involvement of the operations group in setting of PM dates, or input into the setting of work priorities and schedules.

Seek perfection is just that. When you think you’ve got it all right, start all over again based on your new standard.

Future Lean Maintenance columns will provide examples of lean techniques such as elimination of the Seven Forms of Waste (MUDA), improved set-up times (SMED) and everything in its place (5Ss) in the maintenance process, leading to Total Productive Maintenance.

Cliff Williams is engineering and maintenance manager at Multipak Ltd., Mississauga, Ont., and a consultant with TMS Total Maintenance Solutions of Markham, Ont. He can be reached at williamsc@sprint.ca.