University of Twente Student Theses

Lead time reduction at Fokker Aerostructures B.V.: “Design of a logistical concept to reduce the lead time of the chemical treatment process and the paint shop at Fokker Aerostructures B.V”

Esveld, H.G. (2010) Lead time reduction at Fokker Aerostructures B.V.: “Design of a logistical concept to reduce the lead time of the chemical treatment process and the paint shop at Fokker Aerostructures B.V”.

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Abstract:	Stork Fokker Aerostructures B.V. is facing the problem that the lead time at the Sheet Metal department is too long and unreliable. The objective of this research is to design a logistical concept that reduces the lead time of the production orders that need a chemical treatment and (mostly) a paint job. After analyzing the current situation, we conclude that the waiting time at the batching zone of the chemical treatment installation mainly determines the total lead time of the orders that need a chemical treatment and (mostly) a paint job. The available literature contains a model that is able to optimize the planning of jobs comparable with the orders available at the batching zone. This model is also able to incorporate the differences in batches between two consecutive departments comparable with the chemical department and the paint shop. The complexity of the practical situation in number of orders, flows, programs, and restrictions results in an unacceptable long computation time to optimize the problem with a mathematical model. To improve the performances at the chemical line and the paint shop in terms of lead time and service level, we have to design a logistical concept that incorporates clear working instructions for the operators at the chemical line. To be able to construct a schedule that results in a shorter and more reliable lead time, we analyze the product mix that is offered to the chemical line in terms of orders per flow number and program. Based on the historical data of the chemical line, we conclude that the product mix is too diversified and the arrival process is too unpredictable to construct a fixed schedule that can guarantee an acceptable and reliable lead time. To improve the lead time, we have to develop a schedule that is able to react on the available orders at the batching zone. We decide to develop a number of alternative schedules that contains fixed time windows for each type of chemical treatment. This cuts the initial problem into smaller problems. To determine the right flow number during these time windows, we make use of the FIFO concept. To compare the alternative schedules, we develop a simulation model that simulates the stochastic arrival process and makes it able to analyse how well the schedules react on the unpredictable arrival process. Based on the quantitative results of the simulation runs, we conclude that the use of a structured way of working according to a schedule results in the following improvements without decreasing the efficiency at the chemical line:  Increase in service level from 65-70% to 90-99%  Reduction of average lead time from 3,5 days to 1,5 – 2 days  A more reliable lead time with a decrease of the standard deviation of the average lead time from more than 4 days to 1 day. We consider multiple schedules that are based on a one-cycle schedule or a two-cycle schedule. With a one-cycle schedule, every type of chemical treatment has one time window during the day that it is performed. With a two-cycle schedule we use two time windows per type of chemical treatment. Based on a multi-criteria analysis of the alternative schedules, we conclude that the one-cycle schedule has the most promising results. To test the schedule in practice, we execute a test pilot of one week with the one-cycle schedule. After evaluating the pilot, we recommend the following actions to be taken in the forthcoming period:  Match the workforce with the requirements of the schedule, in number of operators and their capabilities.  Reorganize the batching zone to visualize the available work.  Perform a time study at the chemical line and the paint shop to find the most disturbing effects and eliminate them. Our main conclusion is that implementing a structured way of working at the chemical line, results in significant better performances in terms of lead time and service level. The performances are less independent of a specific schedule, but the one-cycle schedule has the most promising results
Item Type:	Essay (Master)
Clients:	Fokker Aerostructures B.V
Faculty:	BMS: Behavioural, Management and Social Sciences
Subject:	85 business administration, organizational science
Programme:	Industrial Engineering and Management MSc (60029)
Link to this item:	https://purl.utwente.nl/essays/60727
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