Shop Floor Control in Repair Shops: Which shop floor control method can be used for which repair shop?

Cornelissen, Floor (2010) Shop Floor Control in Repair Shops: Which shop floor control method can be used for which repair shop?

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Abstract:The Component Services (CS) department of the KLM, repairs and maintains various components of the airline fleet of KLM and other airlines. The repair shops of CS have to cope with a high variability in the arrival times of the components and a high variability in how to repair them. This makes it hard to predict the processing steps that a component needs to go through and how much time these steps will take. The capacity of the repair shops is more or less fixed. Therefore it is not possible to capture this variability with temporarily increasing or decreasing the capacity. Another problem is that some of the components can only be repaired by specific skilled workers. This makes the capacity even more restricted. These factors make it very complicated to give a customer a reliable Turn Around Time (TAT), although this is demanded by customers. This project investigates the use of shop floor control methods to cope with these uncertainties in the repair shops of Component Services. The objective of this research is to get a better understanding of and advise the KLM on the use of shop floor control methods in the component repair shops of KLM. Not much research is done on the use of shop floor control methods in repair shops. The little research that exists focuses on the use of release methods. A release method determines when and which component will be released with the use of triggering mechanisms (when to release the next order) and sequencing rules (which order to release next). Based on the literature we selected the following three triggering mechanisms and three sequencing rules.  “Immediate release” triggering mechanism. After the components enter the shop, they are immediately released to the shop floor.  “Work In Process (WIP) level for the whole system” triggering mechanism. The components are released when the total number of components on the shop floor falls below a certain level.  “WIP level per component group” triggering mechanism. The components are divided into groups that need similar resources for the repair. When the number of components on the shop floor of a specific group is below a certain level, the next component of this group is released.  First In First Out (FIFO) sequencing rule. The component that enters the buffer first, is released first  Earliest Due Date (EDD) sequencing rule. The component that has the earliest due date, is released first  Minimum slack (MS) sequencing rule. The component that has the least slack (= due date - processing time), is released first The literature concludes that the use and effectiveness of the release methods depends on the characteristics of a shop. Based on the literature and the experiences in the shop, the following four shop characteristics that might influence the choice of release method are defined.  Workload of the shop. The workload of the shop is determined by the amount of components that enter the shop and the capacity the shop has to repair all these components. If the capacity suffices the input, the shop is in balance. 4  The skill level of the mechanics. The skill level of the mechanics is determined by the type of components they are certified to repair. This can be limited or the mechanics can do all processing steps.  Differences in Turn Around Time (TAT) agreements with the clients. The clients of the shop have agreements on when the components need to be finished. These agreements can differ per component  The number of process disruptions. The repair process of the component can be disrupted by not having the right material, resources, or skills for the repair. Table 1 displays the three shop categories that exist in Component Services, based on the shop characteristics. Workload Skill level TAT agreements Process disruptions Category 1 Balanced Limited No differences Several Category 2 Balanced Limited Differences Several Category 3 Balanced Every mechanic can do most repair steps No differences Several Table 1. The three shop categories identified at Component Services Results With the use of a simulation model of one of the shops, the different release methods are tested and the shop characteristics were manipulated in order to test whether these characteristics influence the selection of release method. The simulation model indicates that the immediate release triggering mechanism in combination with the EDD sequencing rule is the most suitable release method for the simulated shop in the current situation. Below, we describe the influence of the shop characteristics.  The decrease of workload does not influence the selection of release method.  The increase of workload does change the selection of release method. The WIP level for the whole system triggering mechanism in combination with the EDD sequencing rule is recommended when the workload is increased.  The skill levels of the mechanics we tested do not influence the selection of release method.  The differences in TAT agreements do influence the selection of release method. The immediate release triggering mechanism in combination with the FIFO sequencing rule is recommended, when there are no differences in TAT agreements.  The number of process disruptions does not influence the selection of release method. Conclusion Based on these results, Table 2 displays, per shop category identified in Table 1, the release method this research recommends. Triggering mechanism Sequencing rule Category 1 Immediate release EDD Category 2 Immediate release FIFO Category 3 Immediate release FIFO Table 2. The recommended release methods for the three identified shop categories
Item Type:Essay (Master)
Clients:
KLM Engineering & Maintenance
Faculty:BMS: Behavioural, Management and Social Sciences
Subject:85 business administration, organizational science
Programme:Industrial Engineering and Management MSc (60029)
Link to this item:http://purl.utwente.nl/essays/60722
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