1Closed-Loop Measurement of Equipment Efficiency and Equipment Capacity Robert C. Leachman Dept. of Industrial Engineering and Operations Research University of California at Berkeley Berkeley, CA 94720-1777 January, 2002 Abstract Formal definitions for the components of efficiency and capacity, mathematical formulas for computing overall efficiency, and data collection strategies are proposed for rigorous measurement of equipment efficiency and equipment capacity. Measurement of overall equipment effectiveness (OEE) under the TPM paradigm is revised to become a true quantitative measure of efficiency that we term overall equipment efficiency. The measurement also is extended to support the maintenance of capacity parameters for production planning. The weaknesses of equipment analyses based on utilization and aggregate UPH (units per hour) figures are contrasted against the robustness of the proposed approach. Applications in semiconductor factories are discussed. 1. Introduction As a successor to the Total Quality Management (TQM) paradigm, Total Productive Maintenance (TPM) is now a prominent paradigm driving manufacturing improvements in a number of Japanese industries, particularly the semiconductor industry. TPM also has gained a foothold in some American companies. While TQM's immediate focus is on efforts to perfect product quality, TPM's immediate focus is on efforts to perfect equipment productivity. Strategies under the TPM paradigm include increasing equipment knowledge within the manufacturing workforce, improving maintenance procedures, changing procedures to reduce or eliminate setups, test procedures and idle time, making modifications to increase machine speed or reduce scrap and rework, etc. Successful TPM is facilitated by rigorous definition and measurement of machine efficiency. Overall efficiency is expressed as a function of a number of mutually exclusive components in order to quantify the various kinds of productivity losses that are occurring, whereupon the most appropriate improvement initiatives may be formulated. A number of authors have written about the definition and measurement of overall equipment efficiency (OEE) under the TPM paradigm , , , . An unremarked potential by-product of rigorous and routinized measurement of OEE is the opportunity to realize routinized and rigorous maintenance of capacity data for the purposes of planning and scheduling. The needs of equipment assessment and equipment improvement and
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