Methods for reducing changeover times through scheduling
To compete in today's manufacturing markets, it is necessary to have diverse product lines that can be manufactured and delivered to the customer in the shortest time possible. Producing a large range of products in a short amount of time is only possible through efficient and effective manufacturing practices. One way to improve the efficiency of a manufacturing system is to reduce the time required to change from product “A” to product “B”. This will decrease the lead time of the product and increase the overall equipment effectiveness for the equipment used to process the product. Decreasing the time required to change between the manufacture of two products is known as changeover reduction. In this thesis three strategies are described for reducing changeover times for vertical CNC milling machines for a company that manufactures industrial equipment. The first changeover reduction strategy is focused on the implementation of the single minute exchange of die methodology. This method is widely used throughout the manufacturing industry as a systematic, and extremely effective, way to decrease changeover times. The setting of this research provided an excellent opportunity to implement the methodology. The second strategy developed a way to schedule all of the components of the same product so that the components are processed during the same time period. The third strategy utilized the rank order clustering algorithm to create a schedule that organizes jobs into groups that share similar changeover activities, such as the required tools and fixtures. After observing and analyzing six changeovers, a methodology was developed to arrange the changeover tasks in order to maximize the manufacturing time of the CNC milling machines. Applying the proposed changeover methodology to one of the analyzed changeovers shows that a significant reduction in changeover time is possible. It was also found that scheduling components of the same product so that they are produced in the same time period reduces the overall changeover time of the product. Lastly, applying the rank order clustering algorithm reduced the number of tool and fixture changeovers. If the methods described in this thesis are implemented, then a reduction in changeover time should be seen. Applying the discussed methods will also result in improved overall equipment effectiveness and a reduced lead time. These methods can also be applied to other companies with similar changeover problems.
Whitney P Duncan,
"Methods for reducing changeover times through scheduling"
Dissertations and Master's Theses (Campus Access).