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is not realistic. However, as a gross average, this approximation is good enough for the time frame when the CCR would process the order and the total amount of capacity required. The first operation would probably be completed soon after the order is released to the floor, while the last one would be done significantly later. However, on average, all the operations will require approximately the time allotted in the planned load. We want to estimate the possible due date promised to the next order received. Then, the average time frame when the CCR would process the order is good enough, assuming, of course, the production buffer is long enough for the six iterations through the CCR.

In what sense does the planned load serve as a load control? The planned load represents a time frame that the CCR has to process every order to be delivered within the horizon. Therefore, the planned load, the date when it will finish on the CCR, should definitely be earlier than the horizon at hand. It needs to be shorter than the horizon by at least the time that is required by an order to move through the CCR to completion. For example, if the planned load finishing date on the CCR is three weeks from now and the horizon is four weeks, then the minimal request for load control is that one week is more than enough for an order to flow from the CCR until completion of production for the order.

Surely, the planned load does not ensure that every single order, which is included somewhere in the order logbook, has enough time to complete production on time.

Determining the Safe Dates

Traditional DBR, like most production planning methods, assumes that once an order is received for production planning it already includes a mandatory completion date. Of course, there are times where a time quotation is required, but in most cases production planning gets the orders with the dates and then they must do their best to meet all of the requests on time.

In DBR methodology, there is a check, which is done immediately after the finite-capacity schedule of the CCR is completed, to validate that all the promised deliveries are secure. The check compares the time the CCR is scheduled to finish processing the order and the completion time for producing the order. The time difference must be equal to or longer than half of the shipping buffer. As a reminder, the shipping buffer in DBR is the liberal estimation of the required time between the CCR and order completion. Eventually, in the process of scheduling the CCR, that time difference cannot always be maintained. Sometimes the schedule provides more time than required for the order to pass from the CCR to completion, but many times less time than the shipping buffer is provided. Does it mean that when the time difference between the CCR schedule and the due date is somewhat less than the ideal shipping buffer the order is doomed to be late? The assumption used in that check is that as long as half of the shipping buffer time is provided, then the completion time is secure enough because BM would give the order enough priority to pull the order through the remaining work centers to completion.15

In S-DBR, we need to develop the procedure for ensuring that the completion time can be secured. However, let’s now challenge the assumption that production planning is given a due date and then, in some cases, Sales needs to contact the client and renegotiate that date. In other words, we must let Sales know at all times what dates can be promised to any new orders coming in. DBR production planning could not give a due date to an order that is not yet included in the schedule. Of course, one could always look at the DBR schedule and based on it assume what a safe date might be. Only later will the DBR schedule confirm the date or advise to delay the promised delivery date. In S-DBR, we can be much more flexible.

A procedure that would make it clear what dates can be safely promised to any incoming order generates important benefits. First, once Sales is convinced that those dates are not manipulated