Single-Level Bills of Material Data Set

The BOM Procedure

Single-Level Bills of Material Data Set

The BOM procedure uses the Single-level BOM data set as input data with key variable names being used to identify the appropriate information. Table 1.2 lists all of the variables in this input data set, with their type and their interpretation by the BOM procedure. It also lists the options in the STRUCTURE statement that are used to identify those variables.

Table 1.2: Single-level BOM Data Set and Associated Variables

Variable	Type	Option	Interpretation
Component	same as Part	COMPONENT=	Component name or
			number
ID	character or numeric	ID=	Additional information
			about the part
LeadTime	numeric	LEADTIME=	Lead time of the part
Part	character or numeric	PART=	Part name or number
QtyOnHand	numeric	QTYONHAND=	Quantity of the part that
			is currently on hand
Quantity	numeric	QUANTITY=	Quantity of the component
			required per unit of part
Requirement	numeric	REQUIREMENT=	Gross requirement of the
			part

The value of the Requirement variable should be missing for most parts, except master schedule items. A master schedule item is a part that is selected to be planned by the master scheduler. In general, final products are master schedule items. Some companies like to select a few items that are deemed critical in their impact on lower level components or resources as master schedule items. The requirements of the master schedule items are also called independent demands. In the Single-level BOM data set, if the value of the Requirement variable is greater than or equal to 0, then the procedure treats the item identified by the Part variable as a master schedule item and assumes that its gross requirement is planned by the master scheduler. The gross requirements of other parts (also known as the dependent demands) are determined by the procedure as the value of the net requirements of their parent items times the quantity required to make one unit of the parent items. This process is called the dependent demand process (Clement, Coldrick, and Sari 1992). In general, the information in the Part and the LeadTime variables and all ID variables are stored in the company's part master data file. The part master data file gives various details of fairly constant data associated with the individual parts. It might contain the following kinds of data (Clement, Coldrick, and Sari 1992):

part number or name
part description
engineering drawing number
revision level
commodity code
cost
product code
lead time
order quantity
item type or status
latest engineering change dates
lot size
planner/buyer codes
unit of measure
make or buy

The information of the Part, Component, and Quantity variables can usually be found in the product structure data. The product structure data describe the material content of a product at each stocking level in the manufacturing process. The quantity of each part that is currently on hand is contained in the company's inventory data, and the gross requirements of master schedule items are from the master production schedule (MPS). The Single-level BOM data set contains information from all these data sets. You can combine the part master data file, inventory data file, and master production schedule, based on the common variable Part, to a new data set. Then you can either append the product structure data (part-component relationship information) to the end of the new data set (as in Example 1.1) or merge them together (as in Example 1.2).

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