【正文】 standing and Managing The Constraints… Utilization of an operation is not the same as activation. In the TOC concept, an operation is considered activated only when it is providing benefit for the entire system to give more output. The operation may be utilized, or producing material not needed until some time in the future, but that does not necessarily help the entire system. Do231。lent Sezen 32 Understanding and Managing The Constraints… A schedule should be determined by using all the operational constraints. In many operations schedules are set sequentially. TOC argues that all constraint areas should be considered at the same time when making a schedule. The theory also argues that lead times are a result of the schedule and should not be determined before the scheduling process. Do231。lent Sezen 36 Improving the Process using TOC Principles… 2. Exploit the constraint. Find methods to maximize the utilization of the constraint toward productive throughput. For example, in many operations all processes are shut down during lunchtime or during breaks. If a process is a constraint, the operation should consider rotating lunch periods so that the constraint is never allowed to be idle. Do231。lent Sezen 40 Notes on the five steps: The third step is acplished by Releasing material at the gateway (first processing) center at a rate that will keep the constraint busy. Prioritization of nonconstraint tasks based almost exclusively on constraint needs. Do231。lent Sezen 44 Notes on the five steps: At one time the mix of process requirements may point to one constraint, while at another time the mix may create an entirely different constraint. If the constraint shifting occurs frequently, then there could be far too little opportunity to apply the TOC approaches on one constraint before it shifts to another point in the process. Do231。lent Sezen 48 Impact On Operation Strategy… If, on the other hand, there are processes early in the overall process that have poor quality yield, the constraint should be placed later in the overall process. Some processes, especially certain chemical processes, have poor yield by their very nature. The idea is to have those processes placed prior to the constraint. Do231。lent Sezen 52 Logistics and the Theory of Constraints… Most activities have statistical fluctuations inherent in their operation. This implies that activity times are not deterministic and deviations about the mean will exist. The TOC approach suggests that it is these statistical fluctuations that make traditional assembly line balancing approaches impractical. Do231。lent Sezen 56 1. The constraint is broken. This is the same basic issue we found with a lean production system. Without much inventory in the system, processes tend to be tightly linked, and the loss of any operation will quickly bring the entire system down. Maintenance bees important for TOC for roughly the same reason as for lean production systems the potential high cost of a drop in throughput for the entire system. Do231。lent Sezen 60 Scheduling and the Theory of Constraints… Drum The drum of the system refers to the drumbeat or pace of production. Essentially, it represents the master schedule for the operation, which is focused around the pace of throughput as defined by the constraint. Do231。. Dr. B252。lent Sezen 67 Multipletime Buffers… Do231。lent Sezen 71 Multipletime Buffers… The same argument applies to the Assembly 2 area. The subassembly from ponents 1 and 2 have constraint time invested, so we would not want them waiting for ponent 3. This calls for another assembly time buffer to be generated at the Assembly 2 area. Unfortunately, the need for buffers has not been fulfilled. Do231。lent Sezen 75 Control Points and Batches… Based on the flow of material and the type of operation, there are specifically defined types of control points that may be important for TOC scheduling, measurement and control. A control point is a point in the process where measures are taken and decisions made based on those measures. Typical control points for TOC include: Do231。lent Sezen 79 Control Points and Batches… Process batches for nonconstraints are l。lent Sezen 76 Control Points and Batches… The constraint this is clearly the most critical control point, and needs to be scheduled carefully based on sales. The first operation (or the gateway) it is quite important to release the right material at the right time into the system so it will reach the constraint. This is, in effect, the rope of the drumbufferrope system. Diverging points these points are where a mon part can be processed into one of several different options. They must be managed to ensure that material, especially constraint material, is used in the correct manner for the correct assembly. Do231。lent Sezen 72 Multipletime Buffers… It is possible that the final product with its constraintinvested material could be held up at shipping, since the processes that take place between assembly and shipping have not been part of the protection. This implies an additional time buffer before the shipping area, referred to as a shipping time buffer. Do231。lent Sezen 68 Multipletime Buffers… The subassembly is then assembled with ponent 3 after it is processed from raw material. The final product is then shipped to the customer. The constraint in the system is located in the middle of the processing for ponent 1. Do231。. Dr. B252。lent Sezen 61 Drum Put in other terms, the drum can simply be considered as the work schedule of the anization39。lent Sezen 57 three reasons for a loss of throughput…