Does Lean Manufacturing Exclude MES and APS?

In a review of my new book “MES Guide for Executives,” a Dutch Lean Manufacturing specialist wrote:

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“Discrete manufacturers often apply Lean Manufacturing techniques. Because the shop floor becomes self-controlling (think of the kanban system), many of those potential MES advantages are lost. Not only does a detailed scheduling system become superfluous, lean manufacturers also strive at making only good products. When this is working you don’t need to report material usage and so on. Summarizing you could say: the less mess on a shop floor, the less need for an MES!”

Does Lean indeed make manufacturing execution systems (MES) superfluous? Last week, I visited a factory with a rather straightforward production process: they plasticize paper, coat it, cut it to length and package it. How hard can it be?

But it appeared to be more difficult than I thought. The changeover of the coating machine takes a lot of time. That’s why they preferably produce the same types of orders for a whole week. Then they change the machine to produce orders from type B. Because they want to have as little work-in-process inventory (WIP) as possible, the plasticizer only produces small orders that can be processed by the coater that same week. Unfortunately, that means that the plasticizer needs many changeovers.

The operators have done a single minute exchange of dies  (SMED) project, so they are able to change over the machine relatively quickly. Nevertheless, this is a lot of work and has a negative impact on the efficiency. As you may have noticed, this process factory does apply the kanban method that the Lean specialist refers to in his statement. The plasticizer feeds the coater and only delivers orders that the coater can process.

Nevertheless, the production manager is not happy. “What if we increase our WIP a little so we can combine the small orders on the plasticizer into bigger orders, thus requiring less changeovers on the plasticizer?” he asked me. Their general manager has a strong focus on inventory levels and the production manager feels the challenge to prove to his boss that lower changeover cost (and thus lower waste) could compensate for the higher stock costs.

Scheduling helps

Detailed scheduling not required, you were saying? The relationship between stock levels, order combinations, machine turnovers and waste is so complex that a human being can not immediately see how a change in one aspect impacts the key performance indicator (KPI) of the other aspects. Detailed scheduling systems provide the possibility to quickly compare different optional schedules, taking into account machine turnovers, cleaning and dependencies between machines. You can see how the schedules impact stock levels, efficiency and other KPIs. In this company, Lean does certainly not make the use of an advanced planning and scheduling system (APS) superfluous.

But what about MES? A good MES provides information about the amount of machine disruptions, waste, stops and the like. Lean focuses on the prevention of these aspects, but in order to get rid of them, you first need to find them. In a shop floor with only two laborers, I understand that you don’t invest in an MES. But in a 24/7 company where production takes place in shifts, people soon have a lack of insight.

So in process industries, Lean does not make MES and APS superfluous. On the contrary, Lean Manufacturing can hardly be realized without such information systems.

Bianca Scholten, bianca.scholten@task24.nl, is a Principal at IT integration firm TASK24, in The Netherlands, and a voting member of the SP95 committee. Her books “The Road to Integration; a Guide to Applying the ISA-95 Standard in Manufacturing,” and “MES Guide for Executives: Why and How to Select, Implement and Maintain a Manufacturing Execution System,” are available at www.ISA.org

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