Suchergebnisse

The selection of an appropriate enterprise resource planning (ERP) solution remains a complicated task. Since the fundamental role of an ERP solution is to support corporate operations, a key consideration is its alignment with the process requirements of the firm. This work is an investigation into the impact that this alignment has on perceived operational performance. Data are collected using a survey administered to representatives of the machine manufacturing industry. The findings suggest that the alignment of ERP solutions with operational needs is crucial to perceived ability to deliver orders on time and to general satisfaction with the ERP solution.

This research examines the use of both frozen and replanning intervals for planning the master production schedule (MPS) for a capacity‐constrained job shop. The results show that forecast error, demand lumpiness, setup time, planned lead time, and order size have a greater impact on the mean total backlog, total inventory, and number of setups than the frozen and replanning intervals. The study also shows that a repetitive lot dispatching rule reduces the importance of lot sizing, and a combination of repetitive lot dispatching rule and single‐period order size consistently produces the lowest mean total backlog and total inventory. The results also indicate that rescheduling the open orders every period produces a lower mean total backlog and total inventory when the forecast errors are large relative to the order sizes. This result suggests that the due date of an open order should be updated only when a significant portion of the order is actually needed on the new due date.

Previous research, conducted before the Internet was widely accessible, has shown that information sources and channels can influence the initiation, adoption, and implementation of innovations. The field of operations management faces a wide variety of innovations, the eventual diffusion of which may depend on changes that are now occurring in information technology. This study uses data collected from two surveys, one conducted postally and one conducted over the Internet, to identify how operations management practitioners, consultants, academics, and students perceive and use information from various sources (books, journals, etc.) and channels (conferences, the Internet, etc.). The results indicate that the Internet is growing in importance as an information channel, with more than 40 percent of all respondents having used information obtained from the Internet during the year preceding our study. Although most respondents view that information as being less important to them professionally than information from other sources and channels, those who use the Internet most frequently have a much higher opinion of the information it provides. Multidimensional preference analysis indicates that the Internet is perceived as being quite different from traditional sources and channels, but because of that difference it currently meets the preferences of only a small subset of individuals.

ABSTRACTThis paper reports the results of simulation experiments that compared the inventory efficiency (i.e., the customer service level provided by a given level of inventory) for two different inventory policies. One of these policies uses time‐phased information on future demands like that found in material requirements planning (MRP) systems, while the other (the reorder point or ROP policy) relies on forecasts implicitly based on average past demands. After establishing that the MRP policies dominate for reasonable conditions, the uncertainty of the forecasts was manipulated until the policy preference was reversed. It requires a very perverse relationship between the forecast and actual demand before ROP beats MRP on inventory efficiency.

ABSTRACTThe dual problem of work tour scheduling and task assignment involving workers who differ in their times of availability and task qualifications is examined in this paper. The problem is presented in the context of a fast food restaurant, but applies equally well to a diverse set of service operations. Developing a week‐long labor schedule is a nontrivial problem, in terms of complexity and importance, which a manager spends as much as a full workday solving.The primary scheduling objective (the manager's concern) is the minimization of overstaffing in the face of significant hourly and daily fluctuations in minimum staffing requirements. The secondary objective (the workers' concern) is the minimization of the sum of the squared differences between the number of work hours scheduled and the number targeted for each employee. Contributing to scheduling complexity are constraints on the structure of work tours, including minimum and maximum shift lengths and a maximum number of workdays.A goal programming formulation of a representative problem is shown to be too large, for all practical purposes, to be solved optimally. Existing heuristic procedures related to this research possess inherent limitations which render them inadequate for our purposes. Subsequently, we propose and demonstrate a computerized heuristic procedure capable of producing a labor schedule requiring at most minor refinement by a manager.

ABSTRACTThis paper presents a new integrative concept for job sequencing, dispatching, and lot sizing. The interrelation between these procedures and their impact on flow‐time performance is examined in a capacitated production environment. Generally, lot‐sizing decisions are made without regard to shop conditions and do not consider their impact on job sequencing procedures. The repetitive lots (RL) concept (developed and tested in this paper) attempts to integrate these decision processes.RL uses a number of features which have not been considered jointly in either the lot‐sizing or job‐dispatching/sequencing literature. These include operation batch sizes which vary by operation, transfer of work within the shop in quantities less than operation batch size, and the use of overlapped operations. A simulation model is used to analyze flow‐time characteristics in a hypothetical production system. Traditional measures of flow‐time performance are compared to a set of nontraditional measures which capture the interaction between lot sizing and the sequencing procedure used.

ABSTRACTThis study compares different strategies for arranging machines in a facility. Computer simulation of two different machine shops was used to compare process layout (the arrangement of groups of machines where the machines within a group are interchangeable) to cellular layout designed using group technology concepts (the use of manufacturing cells where each cell contains different types of machines dedicated to the production of similar parts). Four layout strategies, including process layout, cellular layout, and two hybrid layouts, were compared in two machine‐shop models. The shops that used cellular layouts had shorter setup times, lower machine utilization, and shorter distances traveled, on average. The shops with process layout, however, had better performance on queue‐related statistics such as work‐in‐process inventory level and average flow time. This suggests that a well‐organized traditional job shop may be able to achieve overall performance that at least is comparable to that of the same shop using cellular (group technology) layout.

ABSTRACT:This paper presents results of a hierarchical, fixed‐question survey that sought responses about flexible machining cells, flexible labor cells, and concurrent changes in plant operations among nonelectrical machinery manufacturers in Illinois, Indiana, Michigan, Ohio, and Wisconsin. General results indicate that the majority of firms in the American Midwest do not possess flexible manufacturing capability. Of those that do possess this capability, most adopted flexible labor cells prior to adopting flexible machining cells. These cells are small, employing relatively few workers and producing a limited line of products. While the adoption process has been plagued with training, scheduling, and integration problems, most plant managers are pleased with the performance of their flexible manufacturing cells. Management has been reluctant to break out of traditional relationships with suppliers, to trim levels of management and to explore strategic alliances with competitors. Survey results are disaggregated by year, size, positon‐in‐organization, and by union affiliation.