On a complex assembly that contains many components, an item may appear several times on the same drawing and product structure. Use Reference to identify a component that appears multiple times on the same parts list.

The reference code can be a drawing reference number that helps to relate a component to a specific position on a drawing, or a code associated with an engineering change order or an engineering change notice. The system uses parent, component, reference, and start date to define a unique product structure record. A component can have the same parent and same reference as long as the start dates are different.

Since the system uses product structures to store configuration bills, you can also enter the feature code for configured products in Reference.

The way an item is manufactured can change over time. New components can be added or unnecessary ones deleted. Use effective dates to store relationships for historical, current, and future product structures.

All parent-component relationships are identified by a start and an end effective date. The start and end effective dates indicate when a relationship is active. A relationship is effective through the end date and becomes obsolete the next day.

See Engineering Effectivity.

Specify how much of this component is needed to make the parent item. In discrete manufacturing, items are made in individual units, and the component quantity is the amount needed for a single unit of a parent product. For example, two screws are required for one pair of sunglass frames.

In process manufacturing, products are made in batches and the component quantity per parent on a formula or recipe is stated with respect to a batch quantity for the parent product. Since the only economical way to coat lenses is in batches, the amount of a particular coating might be specified for a batch of several hundred lenses.

Depending on the product, some components may be lost or unusable as a result of the manufacturing process. There are two ways to anticipate this loss:

The scrap factor is the percentage of a component expected to be lost during manufacturing. The system uses this with the quantity per to calculate component requirements for work orders and MRP. When a scrap factor is used, component quantities are almost always extended into fractional amounts and not whole units, making it difficult to use with items always handled in discrete quantities.

Using scrap percentages other than zero promotes waste and can conceal quality problems. If additional quantities are consistently required, consider changing the component quantity per directly. This avoids the problem of fractional quantities but may result in even greater waste than using the scrap factor. Continuing the example of the sunglasses, it is not realistic to change the quantity per on the left lens to 2. If you did so, the system would always plan that 200 left lenses would be necessary to make 100 pairs of sunglasses.

Product structure relationships normally have a blank structure type code. Other codes are used for special applications.

Option and planning bills are used to create production forecasts.

See Forecasting/Master Schedule Planning.

Not all of the components of a manufactured item are always required at the beginning. Normally, the differences in timing are not significant. However, if components are required long after the start date and/or the cost of those components is significant, consider using lead time offset.

Enter a positive or negative number, indicating the number of days after or before the start of an order when this component is required. MRP uses lead time offset to determine the need date for components and segregate them on separate picklists for individual work orders.

Enter the number identifying the operation in the routing or process where this component is used. When specified, operation has the following effects: