【正文】 throughput that may end up as inventory. Some accounting systems promote high production rates even if the sales are lower. Do231。lent Sezen 25 Understanding and Managing The Constraints… Ideas are not solutions. Generating ideas can be beneficial, but only if there is followthrough to develop the idea into a solution and then implement it pletely. Do231。lent Sezen 24 Understanding and Managing The Constraints… System constraints can be either physical constraints or policy constraints. Policy constraints are generally more difficult to find and eliminate, but the elimination of a policy constraint generally provides a more pronounced system improvement. Do231。lent Sezen 23 Understanding and Managing The Constraints… Eliminating the undesirable effects provides a false sense of security. Working on problems (often really symptoms) without finding the root cause tends to provide shortlived improvements. On the other hand, eliminating a core problem generally eliminates all of the undesirable effects associated with it. Do231。lent Sezen 22 Understanding and Managing The Constraints… Core problems are almost never obvious. They tend to show themselves as a series of undesirable effects, most of which are really symptoms of the underlying problems. Do231。lent Sezen 21 Understanding and Managing The Constraints… Most undesirable system effects are caused by a few core problems. Solving a symptom of a problem will often do little good. If the core problem remains, the symptom (or another one associated with it) will likely reappear very soon. True longterm relief from the undesirable effect will occur only if the core problem is identified and corrected. Do231。lent Sezen 20 Understanding and Managing The Constraints… Knowing what to change requires a plete understanding of the system and the system goal. Often in TOC, the system goal is to make money through sales, not production. Production pleted without a sale (making and storing inventory) does not contribute to the goal of the pany until it does bee a sale. Do231。lent Sezen 19 Understanding and Managing The Constraints… Systems are like chains. Each system will have a weakest link (a constraint) that will limit the performance of the whole system. Do231。lent Sezen 18 A system optimal performance is NOT the sum of local optima. If all parts of the system are performing optimally, the system as a whole will probably not be performing optimally. In other word s, it is virtually impossible to obtain a perfect system balance. Even if the system was designed to be perfectly balanced, normal variations in performance will inevitably cause some degree of imbalance. Do231。lent Sezen 17 Understanding and Managing The Constraints… A system optimal performance is NOT the sum of local optima. Any system that is performing as well as possible usually implies that not more than one part of the system is performing at an optimal level. Do231。lent Sezen 16 Understanding and Managing The Constraints There are several fundamental guidelines developed for understanding the TOC principles and how to manage a constraining process. Some of the more noteworthy guidelines include the following: Do231。lent Sezen 15 Fundamental Principles of the Theory Of Constraints… One of the key points made by this example is that products do not really have a profitpanies do. This point helps to view the operation more as a system rather than as a set of largely independent functions. Such a view is a critical part of managing by TOC principles. Do231。lent Sezen 14 Fundamental Principles of the Theory Of Constraints… TOC principles make the point that only sales should be counted as operational throughput. Another accounting implication is the labor cost itself. Most traditional accounting systems view direct Iabor as a variable cost. TOC principles, on the other hand, contend that in the short run all operational costs except direct material are largely fixed and should, therefore, be lumped together into an overall operational expense. Do231。lent Sezen 13 Fundamental Principles of the Theory Of Constraints… This approach has implications far beyond how the process is viewed. Even accounting systems are impacted. For example, many accounting systems allocate overhead costs to products based on direct labor hours of production. Such systems may give the impression that producing more product will help to pay for the overhead costs. Unfortunately, if the extra product produced is not linked to actual sales, the result is only more costly inventory and an overall negative impact on the business. Do231。lent Sezen 12 Fundamental Principles of the Theory Of Constraints… Increased efficiency and utilization in processes 1 and 2 will, in fact, only increase inventorynot sales. That issue is one of the key points of TOCthe major measure for any operation should be on the throughput of the anization, or, in other words, the contribution to sales. Any other measures of process efficiency, utilization, or other monly used operational measures have little relevance to the overall effectiveness of the entire system. Do231。lent Sezen 11 Fundamental Principles of the Theory Of Constraints… It should be clear from this simple example that the total operation is constrained by process 3 at 4 per hour. No matter how much efficiency you have in the other processes and how many process improvements are made in processes 1,2, and 4, you will never be able to exceed the overall operational output of 4 per hour unless you address the constraints of process 3. Do231。lent Sezen 10 Fundamental Principles of t