Production Systems Control

In a manufacturing plant, inventories consist of basic materials, good in process, and finished stock. Production planning is concerned with determining what resources (materials,supplies,space,people,and equipment) must be available on-site over time to ensure that manufacturing goals are accomplished. Production control is concerned with timely issuance of available on-site materials to the manufacturing process in such a way that materials are made available in a cost-effective manner where and when needed. The fundamental purpose of inventory is to provide an essential decoupling between unequal flow rates.EOQ and EPQ were early mathematical formulations that considered some of the important costs associated with inventory, but less mathematically rudicable aspects, such as immediacy of quality feedback effects, were not represented in these early formulations. The use of Just In Time (JIT) in recent times has demonstrated that these earlier formulations were therefore significantly incomplete and misleading.
Most manufacturing firms learned to incorporate MRP (Material Requirements planning)systems to keep track of lead times and assembly builds. With the introduction of JIT systems, so much less inventory is work-in-process and is on the production floor for such a short time that, as a component of overall inventories, work-in-process inventory has typically been greatly reduced or even no longer exists as a material category.
The development of the kanban system by Toyota and the concentration of effort on the reduction of setup time by such innovative thinkers as Shigeo Shingo have greatly enhanced the banafits of adopting a JIT philosophy. Reducing the setup time is now seen as productivity opportunity, whereas in the past it was typically ignored-something we wanted to do but never got around to doing.
Quality control and quality assurance promised but often failed to deliver in indentifying quality problem at source. It was never a production responsibility, and so, as a staff function, it rarely got the resources it needed or the attention it deserved for doing the job right. Making quality a production responsibility has focused increased attention on quality needs, and making the production team take responsibility for identifying and resolving quality issues has greatly enhanced the team's effectiveness. The quality control department, a technical staff resource, can now be effectively employed as the technical means of assisting production productivity and of helping quality teams employ the technology needed to resolve problems.
Taguchi techniques, a technical area that for years in the United States has been called design-of-experiments, is a fairly technically demanding area that needs to be applied to production problems by those with sufficient statistical training. A partnership is needed between those in production who have the problems and those skilled in statistical analysis to effectively capitalize on these opportunities.

Source: Industrial Engineering and Management book's