6. Conclusions
The combination of cyclic planning with lean manufacturing has potential for including planning
and control in the lean movement. Looking at the causal mechanisms in this case, we conclude
that lean planning has led indeed to more simplicity and regularity. Depending on the
accompanying organizational arrangements, it may also lead to more involvement and more
internal and external integration. The combination with flow and pull is less straightforward. In
this case it was possible to realize a better synchronization with the demand by exploiting the
distinction between blend level and sku level. This may not always be possible, however.
ERP software turned out to be a complicating factor in introducing cyclic planning. It was
necessary to design situation specific decision support, together with downloading and uploading
procedures. Given the structural inflexibility of ERP, this may be expected to be general.
Simulation is useful in the detailed design of the new planning and control structure, not only
because of its evaluation possibilities, but also because the design of the simulation model helps
also in being sufficiently specific with respect to the questions that have to be answered around
planning and control. Preparing the simulation and especially the process of conceptual modeling
is just as useful as using the simulation (see Robinson, 2004).
The case study confirms the lean principles formulated in the introduction. It shows also that
some of the effects need further research. For instance the quality and yield improvement effect:
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how do the involvement of operational people and the characteristics of the technology and its
use lead to improvements? In case of a well standardized technology, the positive effect of more
regularity may be conjectured to be smaller. Another point that needs more research is the
organizational efforts required for the development, use and maintenance of ERP work-arounds:
what do comparable experiences with respect to downloading and uploading learn about the
complexity of maintaining such procedures? And, maybe, the possibility to realize production
lines with variable speed: how to keep operators effective and efficient?
The effect of cyclic planning cannot be estimated in isolation. It is intertwined with the effects
of more involvement, more organizational and inter-organizational integration, another way of
decision support, etc. Some of the effects can be estimated beforehand, by analysis or simulation.
For some other effects there is some empirical evidence. The just mentioned research
possibilities may also be added here. But most of the effects are so situation specific that one
may not expect to be able to translate such research results right away to concrete estimates for
this situation. This is certainly so for the effects on the total financial result, as it is a combination
of all results.
Case studies are directed to understanding and theory development (e.g. Meredith, 1998), and
not to theory testing. That is how we use this case study. Important relationships have become
clear and it leads to suggestions about future research. But understanding the relationships leads
also to the conclusion that it is very complex to overcome the situation dependence of (the
combination of) all these effects. Case studies, if sufficiently rich described, show us the
restrictions of model oriented research and aspect wise survey research. Case studies are not only
useful for understanding and theory development, but form also the most important means to test
the applicability of the theory. This case study learns us that it is impossible to develop theory
that can be used to predict the performance of the “leaned” system. We have to be satisfied with
models, tools for diagnosis and change, partial theoretic results and rules of thumb. And as long
as that is so, it is valuable to report our experiences honestly and thoroughly. That is what has
been done here.