Performance of merging lines with uneven buffer capacity allocation: the effects of unreliability under different inventory-related costs

This simulation study investigates whether machine efficiency, mean time to failure (MTTF) and mean time to repair (MTTR) significantly affect the performance of uneven buffer capacity allocation patterns for merging lines. Also studied is the trade-off between increasing throughput via bigger buffers and their associated inventory-related costs, since previous studies have shown that higher overall buffer capacity and higher average inventory content result in higher throughput. Results suggest that an ascending buffer allocation pattern (concentrating buffer capacity towards the end of the line) produces higher throughput in shorter, more unreliable lines; whereas the balanced pattern shows better performance in longer, more reliable lines. Increasing average buffer capacity per station and/or having higher average buffer content was found to be more cost-effective in lines with lower machine inefficiency, shorter MTTF and MTTR, and longer lines. Results differed between reliable and unreliable lines since reliable lines were particularly penalised by buffer capacity investiment/maintenance costs due to a relatively low increase in throughput resulting from the addition of extra buffer capacity.

Automated summary

This study explores how machine efficiency, average time to failure (MTTF), and average time to repair (MTTR) impact the performance of uneven buffer capacity allocation patterns in merging production lines. The results suggest that different buffer allocation patterns work better in shorter, less reliable lines compared to longer, more reliable ones. Increasing buffer capacity and content is found to be more cost-effective in lines with lower machine inefficiency and shorter MTTF and MTTR. Reliable lines are particularly affected by buffer capacity investment/maintenance costs, which may not result in a significant increase in throughput.