Delft University of Technology
Faculty Mechanical, Maritime and Materials Engineering Transport Technology / Logistic Engineering
R. den Ouden Modelleren van een werkplek binnen produktie-organisaties. Masters thesis, Report 98.3.LT.5016, Transport Technology, Logistic Engineering.
This thesis describes the experiences and results of the assigmnent executed for LBM Software Development v.o.f. in Rotterdam.
The assignment is titled 'the modelling of a work center within a production organisation'. The developed Delphi syntax, based on the model of the work center, has been implemented in the simulation tool 'Business Moneytor'. This tool downloads main data from an Enterprise Resources Planning (ERP)-system, like SAP R/3 or Baan IV, and makes a model of the enterprise. Simulating with this model makes it possible to analyse the logistic supply chain, execute what-if-analyses and locate bottlenecks.
The developed model contains the following functionality:
General process description for the work center and machine.
Fuzzy sequencing algorithm: this sequencing algorithm determines the next order to process, using a combination of fuzzy logic techniques and dispatching rules. A new aspect of this sequencing algorithm is the usage of an arctangents function as membership function for the determination of the criterion priority.
Sequence dependent setup times: production lines usually have setup times which duration is dependent from the sequence of the defined setup families. To minimise the total setup time, a production cycle can be defined. This cycle defines the fixed sequence of setup families for the work center.
Multi-resources-requirements: the modelling of additional requirements (operators, tool and machine parts) which are necessary for setup-, production- or maintenance-activities.
Malfunction- and maintenance-behaviour of a machine. For a machine several maintenance types can be defined, with their own maintenance activities.
A user interface is also developed to make it possible for the user to edit the work center properties and view the statistical results.
At the moment, not all functions already work in the Business Moneytor. Some parts are already tested, while other parts still have to be completed. The following conclusions can be drawn:
Modelling and programming are interactive activities; they cannot be executed after each other. The structure of an activity-factor diagram is a result of modelling the activities.
The developed fuzzy sequence algorithm is equal to the way an operator of a work center chooses the next work order to execute. The arctangents function is a suitable membership function for a criterion priority.
By using reference points, the user of the Business Moneytor can easily define the membership functions.
The developed information-pull method is a natural and efficient way of modelling the interaction between dynamic systems. Statistics of the performance of a work center give the user the opportunity to analyse the behaviour and results of the work center. The following recommendations are made:
Make the total developed functionality of the work center working. Test the developed Delphi-code and make it sturdy.
Research the developed fuzzy sequencing-algorithm (the performance, the parameter settings). Develop new functionality for the algorithm (such as dynamic weights and dynamic reference points).
Divide the new functionality of the work center in: general extensions, developing specific work centers en custom-made extensions. Develop a 'Production Analyser' and a 'Production Optimiser' for the Business Moneytor.
Reports on Logistic Engineering (in Dutch)
