Production control

About: Production control is a research topic. Over the lifetime, 3969 publications have been published within this topic receiving 64058 citations.

Optimal Lot Sizing, Process Quality Improvement and Setup Cost Reduction

Abstract: This paper seeks to demonstrate that lower setup costs can benefit production systems by improving quality control. It does so by introducing a simple model that captures a significant relationship between quality and lot size: while producing a lot, the process can go "out of control" with a given probability each time it produces another item. Once out of control, the process produces defective units throughout its production of the current lot. The system incurs an extra cost for rework and related operations for each defective piece that it produces. Thus, there is an incentive to produce smaller lots, and have a smaller fraction of defective units. The paper also introduces three options for investing in quality improvements: i reducing the probability that the process moves out of control which yields fewer defects, larger lot sizes, fewer setups, and larger holding costs; ii reducing setup costs which yields smaller lot sizes, lower holding costs, and fewer defects; and iii simultaneously using the two previous options. By assuming a specific form of the investment cost function for each option, we explicitly obtain the optimal investment strategy. We also briefly discuss the sensitivity of these solutions to changes in underlying parameter values. A numerical example illustrates the results.

The last planner system of production control

Abstract: Project controls have traditionally been focused on after-the-fact detection of variances. This thesis proposes a control system, the Last Planner system, that causes the realization of plans, and thus supplements project management’s concern for management of contracts with the management of production. The Last Planner system has previously been successfully applied by firms with direct responsibility for production management; e.g., specialty contractors. This thesis extends system application to those coordinating specialists, both in design and construction, through a series of case studies, one of which also explores the limits of unilateral implementation by specialists. In addition to the extended application, two questions drive this research. The first question is 1) What can be done by way of tools provided and improved implementation of the Last Planner system of production control to increase plan reliability above the 70% PPC level? Previous research revealed substantial improvement in productivity for those who improved plan reliability to the 70% level, consequently there is reason to hope for further improvement, possibly in all performance dimensions, especially with application across an entire project rather than limited to individual specialty firms. That question is explored in three case studies, the last of which achieved the 90% target. The second question is 2) How/Can Last Planner be successfully applied to increase plan reliability during design processes. That question is explored in an extensive case study, which significantly contributes to understanding the design process from the perspective of active control, but unfortunately does not fully answer the question, primarily because the project was aborted prior to start of construction. However, it is argued that Last Planner is especially appropriate for design production control because of the value-generating nature of design, which renders ineffective traditional techniques such as detailed front end planning and control through after-the-fact detection of variances. Issues for future research are proposed, including root cause analysis of plan failures and quantification of the benefits of increased plan reliability for both design and construction processes.

CONWIP: a pull alternative to kanban

Abstract: SUMMARY This paper describes a new pull-based production system called CONWIP. Practical advantages of CONWIP over push and other pull systems are given. Theoretical arguments in favour of the system are outlined and simulation studies are included to give insight into the system's performance.