Schedule Horizons

Schedule horizons are basic data to support the creation of production schedules. A schedule horizon is used to group parts all having the same production schedule horizon information.

When defining schedule horizons, you specify three horizons. The three horizons are defined in work days relative to the current date and the shop calendar and are the schedule horizon, firm horizon, and past due horizon.

Rules when Defining Schedule Horizons

There are some rules that apply to the definition of schedule horizons:

• The schedule horizon must be 1 or greater.
• The firm horizon cannot be greater than the schedule horizon, and it cannot be less than zero.
• The past due horizon is a positive number to express the number of days into the past.

The Different Horizons

Schedule Horizon

This horizon indicates, in work days, the amount of planning data, either master scheduling or material requirements planning, that is included on the production schedule.

Firm Horizon

This horizon indicates, in work days, if some portion of the schedule should be viewed as firm supply by Material Requirements Planning or Master Scheduling and, thus, not re-planned. A firm horizon of 0 means that no firm horizon applies. It is important to understand that the firm horizon is defined in terms of work days. So for example, if the firm horizon is entered as 0 and the current day is Monday, with a conventional five day work calendar, then the firm horizon ends the previous Friday. On the other hand, if the the firm horizon is entered as 4 and the current day is Monday, then the firm horizon extends through Thursday. As a more extreme example, if the firm horizon is entered as 1, current day is Monday, and the work calendar only defines Wednesday as a work day, then the firm horizon extends through Wednesday.

Past Due Horizon

This horizon defines, in past due work days, how out of date a production schedule can get before it should be deleted. If you have not yet met the schedule, then it is unlikely to be achieved. If you enter 5, it means that any scheduled receipt older than five days will be deleted. If you enter 0, it means that all past due schedules will be deleted.

Rolling

Rolling is another feature to be defined when entering the schedule horizons. It provides an option for the planner to deal with the problem of new order recommendations occurring within the firm horizon, which is typically no less than the lead time for the part. MRP and MS consider this information when creating cell schedules. If an order is planned here, it means there is a real demand but it is too late to react. With the rolling feature, you can indicate whether an order that occurs within this horizon should be moved out to beyond the firm horizon. This means that the order will be taken care of as soon as possible. With this feature, you can set the option of whether to roll (move the orders) or not roll (ignore the orders) that occur within the firm planning horizon. The default value is No Roll.