# 15.7.1 Exercise: Load-Oriented Order Release (Loor)

### Intended learning outcomes: Explain the Loor algorithm with given data for a scheduling problem, considering anticipation, loading percentage, and conversion factor.

The first table in Figure 15.7.1.1 shows five orders with their sequence of operations. The data for each operation include the work center, the standard load (e.g., setup plus run time), and a blank column for entering the converted load.

The second table in Figure 15.7.1.1 shows parameters for load-oriented order release, as introduced in Section 15.1.2, as well as their values given for this exercise. The third table holds data for each work center, namely, the weekly capacity, the existing (pre-)load before loading the five orders, a blank column for entering the capacity upgraded by the loading percentage, and blank columns for the summarized load after releasing orders 1 to 5 (that is in the sequence given by the Loor algorithm).

Fig. 15.7.1.1       Given data for a Loor problem.

a.    Load the five orders according to the Loor algorithm.

b.    What would have happened if for operation 3 of order 2 the standard load had been 200 units of time instead of 120?

c.    Discuss whether in your solution the treatment of order 3 was efficient.

d.    What would have happened if order 3 had been loaded before order 2?

Solutions:

a.    The time filter eliminates order 5. This order is declared as not urgent. For the other orders, the conversion factor is applied to their operations. In the third table, the loading percentage multiplies the weekly capacity. Then, order 1 is loaded, followed by order 2. Order 2 is accepted, but it overloads work center B (220 units of time against 200 units resulting from the loading percentage). Hence, order 3 cannot be loaded, because its last operation is at work center B. However, order 4 can be loaded, since it has no operation at work center B.

b.    Order 2 would have overloaded work center A. Hence, order 4 would not have been loaded.

c.    The converted load of order 3 on work center B had only 5 units of time. This would have changed the total load only very slightly. As there was no overloading of other work centers by orders 1, 2, and 4, it might have been wise to release order 3 as well.

d.    Order 3 would have overloaded work center A (405 units of time against 400 units resulting from the loading percentage). Therefore, the algorithm would formally reject both orders 2 and 4. This would result in a low utilization of the other work centers B, C, and D.