Abstract
The lean approach is an idealizing improvement approach that has an enormous impact in the
field of Operations Management. The approach is basically very process oriented and there was
less attention first for planning and control, this being the profession of dealing with all kind of
non-ideal manufacturing and supply-chain restrictions. During the last years, however, planning
and control have been integrated in the lean approach, leading to the concept of lean planning.
Cyclic schedules form an important element of lean planning, certainly in the (semi-) process
industry. The concept of lean planning is rather influential in practice already. This paper
describes a lean planning case study in a semi-process production plant. The case study in itself
is interesting and illustrates well how lean planning can be applied. The case study shows also
that the effect of lean planning or, more specifically, the effect of a cyclic schedule cannot be
isolated from the effect of supporting organizational measures and from the effect of the whole
improvement process. And these effects are very context dependent. The case study helps to
articulate the complexity of developing the lean approach into a theory of production
management and production planning. It shows that it is impossible to predict the performance
of the “leaned” system.
1. Introduction
During the last years, planning and control has been integrated rather well in the lean approach.
Lean planning has an important impact in practice already. This paper describes a lean planning
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case study in a semi-process production plant. The case study is interesting in itself and
illustrates well how lean planning can be developed in practice. It is also used, however, to show
how context dependent the mechanisms are that are coupled with lean planning. That makes the
results of lean interventions difficult to predict. The case study stresses in this way the
complexity of developing the lean approach into theory.
The lean approach is an idealizing approach (see e.g. Ackoff, 1981 or Ackoff et al., 2006), like
TQM and JIT. The lean approach starts with envisaging a world without waste (Womack &
Jones, 2003) and realizes improvement by fighting waste. There is waste of all kinds and hence
the lean approach covers many of the older, more specific idealizing approaches. The lean
approach stresses that broad, operational involvement is required to design and implement
improvements (e.g. Karlsson & Åhlström, 1996). That necessitates organizational measures. But
it is also important to have standard tools available. Tools are important in every idealizing
approach. The lean approach includes the use of tools to diagnose waste, to reveal its causes and
to design improvements. The tools have to be easy to use to make it possible for the operational
people to fight waste where it appears. The lean enterprise institute (www.lean.org) is
instrumental in providing these tools. This combination of broad involvement with how-to-do
schemes is the main factor behind the popularity of the lean approach. See AberdeenGroup
(2006) for an impression of the growth of popularity of the lean approach.
The lean approach is a process improvement approach that gave first less attention to production
planning and control. Production planning and control is directed to dealing properly with supply
and manufacturing restrictions, to be able to meet a fluctuating and uncertain demand. All
practitioners and most academics know that it is necessary to improve the processes first, by
removing such restrictions. The lean approach is directed to such improvements. It includes a
rather effective appeal to realize pull and flow. But the limits of the approach are hardly
recognized and trade-offs are denied. It is not possible generally to cut all slack and to realize
complete flow. But the idealizing character of the approach leads to a structural difficulty in
accepting supply and manufacturing restrictions as the basis for an adequate planning and control
framework. The design of a planning and control framework requires a more quantitative
approach, using OR and simulation. A search on “operational research” on the website of the
lean institute gave only one hit: a university applying lean principles (www.lean.org). Especially
in the process and semi-process industry the manufacturing restrictions are very hard and
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complex generally, leading to a more planning and control oriented approach (Van Donk & Van
Dam, 1996).
More recently, Glenday (2006) has yet been able to connect the (semi-)process industry
production planning and control problems with the lean approach by stressing the possibilities of
cyclic schedules. Cyclic schedules lead to simplicity and regularity. The regularity is helpful in
standardizing the production and change-over processes. The simplicity helps the operators to
play a role in this standardization. It helps them to understand the production patterns and makes
it possible to learn how to deal with deviations and disturbances. Regularity helps to learn faster
and to improve the sensitive points in manufacturing and production control. The introduction of
cyclic schedules helps also in de-centralizing responsibilities with respect to production control.
The ultimate ideal is to produce every product every cycle (EPEC). But it is accepted that this is
not possible for all products. So, the approach has to be combined with a distinction between
slow-movers and fast-movers. The ideas and concepts are not new of course, but integrating
them in the lean movement and tooling them up accordingly has vitalized them. Connecting
cyclic schedules with a lean approach has helped in realizing process improvements and
improvements with respect to planning and control. This paper gives an illustration of that.
The point that remains difficult, however, is to determine realistic estimates for the performance
that can be realized. It is easy to preach that living in a (c)lean house is more pleasant than in a
house full of litter. It is also rather easy to develop generic tools for tidying up the house: broom
and vacuum (c)leaner. It is difficult however to estimate what efforts it will take and how (c)lean
one can get the house in this way. That depends on the holes and corners, the specific structure of
the house. Designing a planning and control framework depends on the possibility to estimate
the performance of alternative frameworks. The performance depends also on the degree of
process improvement that can be realized. This makes a rational design of a lean planning
framework idiosyncratic and complicated. This paper illustrates that as well.
To be able to learn from this case study, the pre-intervention situation, the improvement
measures, the process of change and the resulting effects are described rather comprehensively.
This makes it possible to draw conclusions on the potential of lean planning in this plant. It
makes it also possible to draw more general conclusions about the mechanisms underlying
simplicity, regularity, flow and pull. It contributes to the insight in the possibility to describe
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these mechanisms in general terms and to make them predictable. It sheds also some light on the
question whether it makes sense to try to predict the performance of the “leaned” system.
The next section describes the situation before the intervention. Section 3 describes the
intervention. Attention is given to the course of the project as well as to the implemented
changes. Section 4 describes the results. Section 5 discusses the causal mechanisms behind the
results. Section 6 gives conclusions, on the value of the intervention for the company as well as
on the possibility to draw more general conclusions from the case study.
2. The pre-intervention situation
The plant is the main Sara Lee plant for liquid coffee. Liquid coffee is produced for the “out-ofhome”
market. It is used in coffee machines. The plant combines the production of liquids with
the production of instants, but the case study is restricted to the liquids. See Figure 1 for a sketch
of the material flow. Roasting is a shared operation and extraction is partly shared, but in the rest
of the process the resources are dedicated to either liquids or instants. Liquids use one of the
extraction batteries. The liquid production is given priority on this battery. That, in combination
with the buffer between roasting and extraction, made it possible to restrict the case study to the
liquids. Liquids are produced in about 10 different blends. Packaging increases the variety
drastically to (about) 50 stock keeping units (sku). The customers are the Sara Lee operating
companies (Opco) all over the world. There are about 20 Opco’s. The largest Opco has 40% of
the turnover, the next one 10%. For the larger blends, almost all Opco’s have their own sku, for
smaller blends there are only few different sku’s. The largest blend has about 65% of the
turnover. The liquids are made-to-stock. For part of the Opco’s, the Opco stock is visible for the
supply network planning (SNP) of the plant and is integrated in their stock control. These are
called the “collaborating” Opco’s. Other Opco’s (non-collaborating Opco’s) give just orders.
These are the Opco’s with the smaller turnover. For these last Opco’s the demand can be rather
lumpy. The demand for some blends is seasonal, because part of the demand is for hotels and
restaurants. For one of the blends the high season demand can be more than three times the
average demand.