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Improving warehouse layout design : A study to optimize the warehouse of the hospital of Aruba

Wentzel, S.J. (2017) Improving warehouse layout design : A study to optimize the warehouse of the hospital of Aruba.

Abstract:The Horacio E. Oduber Hospitaal is the only hospital of Aruba. Currently the hospital is building a new building, including a new warehouse. This gives the opportunity to improve the logistic processes of the hospital. The building and racks are already planned, but it has not been decided how this space should be used. This study focusses on this new warehouse. This study aims to find the optimal layout for this new warehouse. For a layout to be optimal, its processes should be efficient, with a low probability of mistakes. It also should support growth, since the warehouse department plans to expand its assortment in the future. Besides the layout, also the way of supplying the hospital departments is important. Since the hospital building changes, the routes that are used to deliver the departments will no longer be optimal, and new ones should be found. The goal of this research is therefore as follows: To design a warehouse layout and order delivery routes in order to make processes efficient and non-sensitive to mistakes, while it remains suitable for growth. To design warehouse layouts, we construct a framework, based on the literature, which consist of all the steps that are required to design a warehouse layout. This framework consist of seven steps: investigate the situation, determine operating policies, select equipment, form a general layout, allocate aisles, determine space usage, and evaluate the resulting options. By following the steps of this framework, we compose several alternative layouts. Those alternative layouts contain all the techniques that can be implemented within the scope of this research, this mainly concerns space allocation and policies of the main warehouse. Out of scope are for example additional purchases, or altering the inventory levels. To select the best alternative, we score them on a list of criteria, which we composed in collaboration with the management and employees of the warehouse. These criteria can be divided over three categories: quantitative, time based and numerical criteria, which are all measured in a different way.  Qualitative criteria, for example the clarity of the present inventory level, are scored by the warehouse department via the AHP method.  Time based criteria, for example the average picking time per order, are scored with a discrete event simulation model that simulates the picking process.  Numerical criteria, for example the percentage of occupied storage areas, are scored through simple calculations. In this case we for example counted the occupied and empty storage slots. To make the scores comparable, we weighted the criteria, and rescaled the results to a scale from 0 to 1. Based on this comparison, we recommend a warehouse layout that contains the aspects in Table 1. This solution results in the lowest average picking time, the lowest percentage of late deliveries, and the most equal workload division. Compared to the current situation, the average picking time would drop with 10%, from 15.7 to 14.1 minutes. The amount of late deliveries would drop even more: from 5.2 % to 0.5%. This drop in late deliveries is mainly the effect of the more equal workload division. Our research shows the importance of variation reduction. The demand of the HOH fluctuates to a great extent. An unequal workload division would cause even more variation. An equal workload division is therefore important. Our research shows its strong influence on the percentage of on time deliveries. It has more effect than, for example, the product allocation, which only affects the average picking time.
Item Type:Essay (Master)
Dr. Horacio E. Oduber Hospitaal
Faculty:ET: Engineering Technology
Subject:56 civil engineering, 58 process technology
Programme:Industrial Engineering and Management MSc (60029)
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