A Case Study of Pratt and Whitney Aircraft\u27s Commercial Spares Planning

This case study, which can be used as a teaching case, deals with jet engine spare parts planning at Pratt and Whitney Aircraft Company, a division of United Technologies Corporation. The case includes background on the company\u27s history and an overview of their jet engine manufacturing operations. The primary focus of the case is on the application and evaluation offorecasting models for demand planning within an ERF system environment. An Excel-based decision support system (DSS), which is available from the authors upon request, enables the evaluation of alternative time series forecasting models for a variety of jet engine spare parts. The DSS workbook replicates the many features and options available in SAP\u27s forecasting system, which has been purchased by Pratt and Whitney

A Case Study of Encoder Shift Scheduling under Uncertainty

This paper illustrates a shift scheduling procedure for a commercial bank's encoder work force for check processing in the presence of daily work load uncertainty. The author presents a chance constraint model for determining the appropriate safety capacity, analogous to safety stock in inventory theory, to meet varying volume demands when forecast errors are present. A series of tests are conducted to evaluate the model's performance under different operating costs, forecast errors, and volume arrival rates, which are based on data collected at Chemical Bank. The results indicate this model provides low cost solutions. This study provides two contributions to managers and management scientists. First, even though the paper illustrates the encoder work force shift scheduling decision, the methodology presented can be extended to other service oriented organizations. The main elements that need to be present are: varying between day work loads, varying within day work loads, uncertainty in estimating work loads, and critical deadlines at specific times during the day. And second, a classification scheme is developed which indicates how the general shift scheduling problem in service organizations can be viewed. This classification system helps to structure this complex problem and indicates how this proposed procedure contributes to this important area.financial institutions: banks, manpower scheduling, programming: stochastic, change constrained

A Simulation Analysis of Tour-Shift Construction Procedures

Work force scheduling research over the last few years has concentrated on the shift scheduling problem in service oriented firms (telephone operators, postal employees, bank encoders, etc.). In all cases, the authors were primarily interested in the evaluating procedures (optimal and heuristic) to determine the appropriate number of workers to be assigned to the available set of work schedules to meet fluctuating work volumes. However, more attention should be given to how the available shift schedules were defined (start times, durations, etc.) and their impact on maintaining good productivity levels. This paper analyzes the impact of six different approaches in defining the available weekly tour-shift schedules. Tests are conducted to evaluate the performance of the six approaches using operating data from Ohio National Bank for the check proof and encoding activity. The results of this study provide some useful managerial insights into the issues of effectively staffing personnel on a weekly basis. First, restrictive employment policies/customs can substantially increase costs. Second, structured procedures can be used to identify and build good employment schedules for a weekly assignment. And third, the structured procedures presented here provide useful cost and productivity information for evaluating various staffing decisions, and weighing these decisions with other intangible factors such as employee morale and turnover.organizational studies: manpower planning, production/scheduling, financial institutions: banks

Cyclical Schedules for Capacitated Lot Sizing with Dynamic Demands

Cyclical scheduling, where the time between production periods for each item is constant, offers simplicity and ease of control compared with noncyclical scheduling, where production periods are irregularly spaced. However, when demands are dynamic, flexibility in the spacing of production periods permits noncyclical scheduling to result in lower total costs. This study investigates the additional cost of cyclical scheduling. We focus upon the capacitated lot sizing problem (CLSP), which deals with planning production on a single, capacitated machine serving multiple items with dynamic demands. To establish cyclical schedules, a mathematical programming model is developed along with a heuristic solution technique and a Lagrangian-based lower bounding procedure. For problems solved in this study, differences between solution costs and lower bounds average less than 1%. Experiments are performed to evaluate the heuristic technique and to compare cyclical schedules with noncyclical ones. For comparison purposes, a noncyclical heuristic and problem sets from the literature are used. New problems based upon operating data from Ford Motor Company are also generated and solved. In this study, cyclical schedules average 4.4% higher in cost than noncyclical ones. Coefficient of demand variation most seriously influences differences in costs. Other significant factors include capacity utilization, setup time, time between orders, and number of items.production planning, lot sizing, heuristics, capacity constraints