Addressing Delivery Related Challenges Of High-Mix Manufacturing Systems
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This thesis aims to address delivery related challenges of high-mix manufacturing systems. Delivery related challenges refer to problems posed by factors, which directly or indirectly impact delivery performance. To address these challenges, it is important to reduce uncertainties in internal processes through identification of factors fuelling uncertainty. It is reckoned that reduction of uncertainty in internal processes, particularly in the upstream sections of high-mix production systems, would reduce the reliance of such systems on time and inventory buffers for sustaining its performance. The level of certainty of the system throughput time has been applied as the means of evaluating the delivery related challenges. The methodology followed in this thesis involves the collection and analysis of data from a case study, based on interviews, video clips and document reviews. The observations from the collected data were then supported with the review of related literature. The major findings from the case study and literature review are that the factors influencing throughput time uncertainty can be broadly categorised as operational, product-induced, structural and equipment-specific or capacity related. In addition, the effects of some of these quantifiable factors on throughput time uncertainty were obtained using statistical analytical techniques such as linear regression and Analysis of variance. The findings from the quantitative analysis of case study data is that batch size and job arrival variability influence throughput time uncertainty. In the same vein, waiting and queueing account largely for delays spanning several days. These delays translate to job arrival variability when there is no control measure for work-in-process inventory. Furthermore, layout and the type of material handling system used in manufacturing systems also compound challenges of waiting and queueing. Job sequencing equally feeds into job arrival variability and waiting time. The effect of other factors that are less quantitative were explained using theoretical approach both in the literature review and case study. In the latter part of this report, a list of factors influencing throughput time was compiled, categorised and approaches for addressing the factors were provided.This thesis intends to contribute to the body of knowledge on delivery related challenges in high-mix manufacturing systems. In addition, the thesis attempts to address internal delivery challenge of the case company considered in this thesis.