A case study paper on equipment availability data analysis.
Tracking bottling equipment line uptime and downtime is a common metric for bottling production lines. The runtime and downtime along with reasons for being down are routinely and semi-automatically recorded. The data is often summarized using the exponential distribution and reported as MTBF and MTTR.
During the design of a new bottling line, the design team used the recorded data from existing lines and equipment to estimate the proposed line availability. If the new line could shorten the run time to accommodate a high mix of products and improve the line availability and thus throughput, the new line would permit significant warehouse savings.
The experienced operator, maintenance and engineering teams knew that the line availability improved as the run duration increased. After the initial setup, the line operator and maintenance crew continued to adjust and improve the operation of the bottling line, thus, overtime improving the line availability. It was not a constant value independent of the run duration. And, the existing calculations based on MTBF and MTTR did not reflect this behavior.
This paper examines the use of expected values of the fitted distributions for uptime and downtime, rather than using MTBF and MTTR. The expected values permit the analysis to study the changes in availability as the run duration changes. The result was the design team’s analysis could tradeoff the run duration and associated throughput with the expected warehouse requirements and cost savings for an optimal bottling line design. This paper primarily explores the equipment analysis and availability calculations.