| The manufacturing lead time concept is fundamental to manufacturing planning and control. It affects production, inventory, and customer deliveries. Regrettably, many aspects of this concept are ignored in the literature of production/operations management.; This study focused upon the manufacturing lead time management in California's electrical and electronic machinery, equipment, and supplies industry. Manufacturing firms with one hundred or more employees were invited to participate in the research.; Six subproblems relating to manufacturing lead time were selected and six appropriate null hypotheses were tested. The subproblems identified (1) factors influencing manufacturing lead time, (2) production planning processes influencing manufacturing lead time accuracy, and (3) techniques reducing manufacturing lead time. These factors, production planning processes, and techniques were then investigated to determine the importance of each of them in two environments: (1) high-volume continuous-production (HVCP) and (2) job-shop production-to-order (JSPTO).; The hypotheses were these: (1) factors influencing manufacturing lead time are equally important, (2) there are no differences in the importance of factors influencing manufacturing lead time between the two environments, (3) production planning processes influencing planned manufacturing lead time accuracy are equally important, (4) there are no differences in the importance of production planning processes influencing planned manufacturing lead time accuracy between the two environments, (5) techniques manufacturers utilize to reduce manufacturing lead time are equally important, and (6) there are no differences in the importance of techniques manufacturers utilize to reduce manufacturing lead time between the two environments.; A five-page questionnaire was designed to provide sufficient information for solving the subproblems and testing the null hypotheses; this questionnaire also provided additional insight into the area of manfacturing lead time management. From 155 questionnaires returned 125 were usable. Both nonparametric and parametric statistical methods were used to analyze the data.; The results of the analyses indicate that each of the factors influencing manufacturing lead time, the production planning processes influencing planned manufacturing lead time accuracy, and the techniques reducing manufacturing lead time are as important in the HVCP environment as they are in the JSPTO environment. Equality of importance, however, does not extist (1) among the factors influencing manufacturing lead time, (2) within levels of details of production planning processes, (3) within ranges of production planning processes, and (4) among the techniques reducing manufacturing lead time.; Among factors influencing manufacturing lead time, commitment to customer on shipping date, ability to plan and control capacity, the number of resource constraints, shop utilization (load), and ability to plan and control inventory level are more important than others. Inventory and order planning, master schedule planning, and production forecasting are more important than other production planning processes influencing planned manufacturing lead time accuracy. In other words, intermediate-range planning processes with an intermediate level of detail have more influence on planned manufacturing lead time accuracy. Furthermore, increasing the output rate by extra manning, increasing shop floor control, reduction of rework and scrap, increasing the output rate by overtime, replanning production output level, combining the planning and control of capacity with the planning and control of mix are more important than other techniques for reducing manufacturing lead time. |
