Apics and ax master planning (4)-time fence time limit (Time Zone)

For a planning system, it is necessary to use time points to define different scopes, because it is impossible for planners to pay attention to all orders at all times. After all, people have limited energy, it is reasonable to define a scope so that planners can only pay attention to the limited orders within a certain time point. Article This article briefly introduces the definition of the time field in apics theory and how to implement these time fields in ax.
Apics Theory
First, extract the definition of several concepts in the apics dictionary.
Planning horizon --- The amount of time a plan extends into the future. for a master schedule, this is normally set to cover a minimum of cumulative lead time pluse time for Lot Sizing low-level components and for capacity changes of primary work centers of key suppliers. for longer term plans the planning horizon must be long enough to permit any needed additions to capaticy.
This concept is actually the definition of the planning outlook, which means how long will it take for me to consider the future needs when planning, it is easy to understand that the shortest date should not be earlier than the accumulative lead time of the materials. If the outlook period is too short, it will be too late for production when you see that the demand starts again, when it comes to outlook, I think of the telescope a while ago. The telescope can see that the range is better beyond the range of the enemy's range. Otherwise, you will see someone else, not far from the dead. This definition also mentions that, for example, the capability changes of the main work center and key suppliers should be considered. In fact, the outlook period is generally set to be far ahead of the cumulative start time. According to the enterprise situation, it is set to be available in year 35.
The above remark goes on. If the outlook is year 35, it is obviously very tiring for planners to pay attention to such a long demand. In fact, it is not necessary. Who knows about such a long period of time? More people are still concerned about the current situation. Therefore, it is obvious that we need to divide the scope of the outlook period into several time periods, some of which are the responsibility of the planners, and some are the responsibility of the computer, so that the responsibilities can be clearly defined to reduce the burden on the planners, of course, it is more out of the need for management and change costs, because the closer the delivery time, the higher the cost of the change plan.
In <Introduction to materials mangement>, the scope of the plan is divided into the following three phases:
Frozen zone-capabilities and materials have been submitted to specific orders, because changes will have high costs and reduce production efficiency, resulting in poor customer service. The change requires approval from the senior manager, which is defined by the demand time limit.
Slushy zone (semi-frozen zone)-raw materials have been purchased and allocated, which is difficult to change, but the priority can be changed. This range is defined by the plan time limit within this time limit, the computer cannot reschedule MPs orders.
Liquid Zone-any changes to MPs can be made as long as they meet the limits of the production plan. The change is usually done by the computer.
From this definition, we can see that the demand time limit and plan implementation of the two time points divide the period from today to the planned outlook into three time periods. In the apics dictionary, both the demand time limit and plan time limit are clearly defined. The definition is relatively long and will not be excerpted here. Briefly speaking, I understand that the demand and demand time limits and plan time limits actually define two key time points, which are defined based on the change cost and owner, changes within the demand time limit must be determined by the senior manager. Planners within the plan time limit can change the time limit, and computers will be responsible for the change after the plan time limit. In practice, the demand time limit is generally equal to or slightly greater than the pre-release date of the Assembly. This means that all the materials required for the finished product have been purchased or finished, and the final assembly is complete, at this time, the cost can be imagined. The planned time limit is generally not less than the accumulative lead time of finished products. In this case, the materials required for the product have been placed in the purchase order or production order, but have not been completed yet, therefore, the impact of order change is not as big as the demand time limit. This definition is not very difficult to understand.
Ax implementation
To be continued