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A method for improvement potential assessment
in a batch planning and scheduling situation
H.J.H. Roeterink, J. Lim, Z. Verwater-Lukszo
and M.P.C. WeijnenDelft University of Technology
P.O. Box 5015, NL-2600 GA Delft
Case study
Central question How can improvements derived
from changes in the production planning and
scheduling situation be specified and assessed
beforehand? Method outline On base of two
explorative case studies in the food industry a
systematic procedure has been developed for
identifying improvement options and estimating
their improvement potential, in relation to a
companys strategic and tactical objectives.
Figure 1 presents the procedure for definition
of an Improvement Potential Assessment (IPA).The
white blocks represent desired information inputs
provided by a company. The colored blocks
represent a predefined framework designed to
process the company-specific information.
Dedicated model System Dynamics model for
supply chain A dedicated model was derived from
Stermans generic model for demonstrating supply
chain dynamics. The internal supply chain
contains all activities, from the receiving of
the raw materials to the shipment of the
products. In this respect, a model connecting
different functional areas in the company has
been formulated raw material inventory,
production, product inventory and customer order
management.
Figure 2. Causal diagram for production sector
Figure3. Influence of safety stock coverage
Simulation model features Input daily product
demand normal distributed Output product
inventory level, delivery lead time, order
fulfillment ratio Num. parameters 14 Num. of
equations 41 Time horizon 250 day Time
step 0.125 day Typical calculation time 10
seconds
The dynamic model was built on base of the causal
diagrams designed for each production sector
production showed in Figure 2. Simulation was
performed using Powersim software. Sensitivity
analysis of the model parameters showed a strong
influence of safety product stock coverage and
target delivery lead time. Figure 3 shows the
influence of the safety product stock coverage on
two logistical performance indicators.

Figure 1. Procedure to derive IPA table
Final remarks Future research will focus on (i)
elaboration of the procedure steps to arrive at a
general applicable method that is transferable to
any industrial practitioner (ii) development of
a general simulation model as part of the method
to quantify the effect of implementing strategic
options for a class of industrial situations.
IPA Table example
Acknowledgement The Dutch Ministry of Economic
Affairs and the Ministry of Education, Culture
and Science financially support the project in
the framework of the E.E.T. program (Ecology,
Economy and Technology). In two of the companies
involved explorative case studies are performed.
The authors gratefully acknowledge the financial
support and the scientific co-operation with
parties involved in the project.
w1 utilization level bottleneck resource
w2 delivery time reliability w3 net
profit Euro Option A use a production
scheduling tool Option B produce also on
Sunday Option C increase bottleneck
capacity with 10
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