A worksheet with the pull tree structure shown is below. For
the example, we propose a manufacturing system. The system uses
two raw materials. RM 1 enters at operation 1 and RM 2 enters
at operation 2. Operation 1 represents the process of obtaining
RM 1 and storing it for use by the system. Its parameters are
shown on the worksheet below. The setup time represents the
time a lot must be retained after arrival before being released
to the shop. Similarly, operation 2 represents the process of
obtaining and storing RM 2.
Operation 3 produces part 1. Part 1 requires five units of
RM 1 and two units of RM 2. Operation 4 produces part 2. Part
2 requires three units of RM 2.
Operation 5 assembles parts 1 and 2 with one unit of each required
for a finished product. Some of the finished items must be recycled
into operation 4. For every unit passing through operation 4,
0.2 units will come from operation 5. For illustrative purposes,
we are stretching logic a bit with this example because its
hard to imagine that the finished item is transferred into a
part for subsequent assembly into a finished item.
The system is to produce 1000 units per week of the finished
product. In addition, 200 units of part 1 and 400 units of part
2 are to manufactured.
The worksheet below shows the parameter and variable assignments
for the example. The replenishment lot sizes for the raw materials
are 10,000 and 6,000 units. Operation 3 is a batch process with
a lot size of 1,000. Most of the other lot sizes are set to
1000. The finished good is packaged into lots of 100.
Discussion about the network is below the illustration.