Object_Oriented Modeling as an Instrument for analyzing a Film Processing Plant
From Proceeding of European Simulation Multiconference,ESS94, Barcelona, June 1_3 1994
P. Giribone

IMPROVEMENTS TO ENHANCE PRODUCT QUALITY

Once tests were completed, an analysis was performed on the model for the different operating situations.
By building the simulator utilizing the object approach, it was possible to obtain interesting tables for each product which indicate the decrease in quality attributable to each component; this evaluation obviously takes into account an entire set of possible stochastic factors (stops during processing, percentage of defects, etc.) which cannot be evaluated without using simulation, since their respective interactions are very complex.
The objective functions used include:
T time needed to produce one type of product
R reject percentage
These two targets can be combined into only one value using a balanced sum to optimize the result; the coefficients used in this case, after normalization, are Ct 0.7, Cr 0.3.
The comparison performed on the objective functions highlighted the economic suitability of the following specific operations on the plant:
_ Verification of the validity of the current method to assign production cycles to the different lots based on a reduction of dead time;
_ Requalification of personnel to ensure that a sufficient number of skilled technicians are working each shift to reduce stops which degrade product quality; this was found to be the most frequent type of action can be used to solve most of the practical problems for the specific case with very limited investments.
To improve the objective functions even further, it was found to be more cost_effective to replace the most obsolete machine rather than overhaul it since with the current production organization philosophy, retooling and resetting times do not have a major impact.
These results have partially confirmed the hypotheses of the plant experts while they have been supported however, with an extensive amount of documentation which otherwise would not be available.

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