Understand BOM quantities
The BOM editor and reports display three separate quantities: Modeled Qty, Actual Qty and Spare Qty. These quantities represent:
• Modeled Qty is the actual number of parts modeled in the CAD application. You cannot edit this field.
• Actual Qty (sometimes called Overwrites) is the actual number of parts required. If no Actual Qty has been entered, then the Modeled Qty is used to calculate the total.
For example, a particular mold assembly requires 50 injector pins; however, the designer only modeled 5 in the CAD application to save time. In this case, the Modeled Qty is 5 and the Actual Qty is 50. You should notice that the Modeled Qty is not added to the Actual Qty or to the total. The Actual Qty overrides the value for Modeled Qty.
• Spare Qty is the number of extras (spares) to allow for breakage, loss or assembly line damage.
The tables below show a simple assembly structure with two sub-assemblies that each contain several instances of a single model part.
|
Modeled Quantity
|
Actual Quantity
|
Spares
|
Total Quantity
|
|||
|---|---|---|---|---|---|---|
 a1 |
-
|
-
|
-
|
-
|
||
| a2 |
2
|
2
|
1
|
3
|
||
 p1 |
5
|
50
|
5
|
55
|
||
| a3 |
3
|
3
|
1
|
4
|
||
| p1 |
10
|
100
|
10
|
110
|
|
Modeled Quantity
|
Actual Quantity
|
Spares
|
Total Quantity
|
|
|---|---|---|---|---|
| p1 |
40
|
550
|
55
|
605
|
The total number of p1 would be calculated like this:
1. Calculate modeled quantity:
a. Total of p1 modeled in a2: 5 x 2 = 10
b. Total of p1 modeled in a3: 10 x 3 = 30
c. Total of p1 modeled in the assembly: 10 + 30 = 40
2. Calculate the actual quantity:
a. Total actual quantity of p1 in a2 (taking into account any spares at the assembly level): 50 x (2 + 1) = 150
b. Total actual quantity of p1 in a3 (taking into account any spares at the assembly level): 100 x (3 + 1) = 400
c. Total actual quantity for the assembly: 400 + 150 = 550
3. Calculate the spare quantity values for p1:
a. Total spare quantity of p1 spares in a2 (not including spares at the assembly level): 5 x 3 = 15
b. Total spare quantity of p1 spares in a3 (not including spares at the assembly level): 10 x 4 = 40
c. Total spare quantity for the assembly: 15 + 40 = 55
4. Add the total actual quantity and the total spare quantity: 55 + 550 = 605
The total number of p1 needed to manufacture a1 is 605.