The BOM Procedure

The BOM procedure performs bill of material processing. It reads all product structure records from a product structure data file and all part “master” records from a part master file, and composes the combined information into indented bill of material. In addition, PROC BOM can also output a summarized parts list, which lists all items and their total quantities required (needed to be made or ordered) in order to fill a given production plan. A production plan is an agreed-upon plan that comes from the aggregate planning function; specifically, it is the overall level of manufacturing output planned to be produced for each product family in each planning period (Cox and Blackstone 1998). Production plan information can be included in the part master file.

According to Cox and Blackstone (1998), a product structure record defines the relationship of one component to its immediate parent. It also contains fields for quantity required, scrap factor, lead-time offset, engineering effectivity, and so on. A part master record typically contains identifying and descriptive data such as part number and part description, and control values (for instance, lead time, lot size, cost, etc.). It may contain “dynamic” data such as inventory status (for instance, quantities on hand) and production plan data (for instance, requirements, due dates, etc.). Part master records are linked by product structure records or bill of material records, thus defining the bill of material.

Also based on Cox and Blackstone (1998), a bill of material (BOM) for an item is a list of all items, ingredients, or materials needed to make one production run of the given item. The bill of material may also be called the formula, recipe, or ingredients list in certain process industries. The way in which the bill of material data are organized and presented is called the structure of the bill of material or the structure of the product.

A variety of display formats is available for bill of material. The simplest format is the single-level bill of material. It consists of a list of all components that are directly used in a parent item. It shows only the relationships one level down. On the other hand, a multilevel bill of material provides a display of all components that are directly or indirectly used in a parent item. When an item is a subcomponent, blend, intermediate, etc., then all of its components are also exhibited, down to purchased parts and raw materials.

An indented bill of material is one form of a multilevel BOM. It exhibits the highest level parent item as level 0, and all components going into this parent item are indented as level 1. All subsequent components are indented one level below their parent items; that is, the level number is increased by 1. If an item is used in more than one parent within a given product structure, it appears more than once, under every subassembly in which it is used. You can view an indented bill of material as a family tree with multiple levels. The summarized bill of material is another form of a multilevel bill of material. It lists all the items and their quantities that are used in a given product structure. Unlike the indented bill of material, it does not list the level numbers of items and does not illustrate the parent-component relationships. Moreover, the summarized bill of material lists each item only once for the total quantity required. Refer to Cox and Blackstone (1998) for further details.

The input data sets used by the procedure are the Product Structure data set and the Part Master data set. The Product Structure data set contains all product structure records, and the Part Master data set contains all part master records for a product, product line, plant, or company. You can combine the product structure data and the part master data into one input data set and assign it as the Product Structure data set; the BOM procedure assumes that all the part master information is also available in this combined data set.

The Indented BOM output data set produced by PROC BOM contains all indented bill of material for the product, product line, plant, or company. This data set is organized in such a manner that it can be easily retrieved and manipulated to generate reports, and can also be used by other SAS/OR procedures to perform additional analysis. See Example 3.1 and Example 3.2 as examples of using the NETDRAW procedure to draw a tree diagram for an indented bill of material. Chapter 4: Bill of Material Postprocessing Macros, describes a collection of SAS macros that use the Indented BOM data set as input data to create reports or perform specialized transactions for maintaining the bill of material.

The BOM procedure can optionally produce a Summarized Parts output data set. This output data set lists all items and their quantities required (needed to be made or ordered) to fill the production plan specified in the part master file. This list is useful in gross requirements planning and other applications.