Describe the bill-of-material position and the where-used list-position as logistical objects. Identify its most important attributes.
Continuation from previous subsection (17.2.3c).
The bill-of-material position logistical object appears in the type of formalized product structure shown in Figure 17.2.3.9.
Fig. 17.2.3.9 The bill-of-material position logistical object.
The left-hand side of Figure 17.2.3.9 shows the content of Figure 17.2.1.3, as shown in Figure 1.2.2.1. The item class is thus in an n-to-n association with itself.
- A product may have different components. Expressed formally, this means that an object of the item class, in its specialization as a product, consists of n different objects from the item class, component specialization.
- A component may occur in different products. Expressed formally, this means that an object of the item class, in its specialization as a component, is used in n different objects from the item class, product specialization.
This n-to-n association is then shown on the right-hand side of Figure 17.2.3.9, broken down into the two corresponding 1-to-n associations. This results in an additional object class, namely, the bill-of-material position, which determines the “product « component” connection or association between two items. This association may be either “item, as a product, consists of” or “item, as a component, is used in,” depending on which side we start with. A bill-of-material position is thus simultaneously a where-used list position.
The where-used list position is a different view of the bill-of-material position.
The view of the bill of material can be described as follows:
- All n bill-of-material positions can be reached from a product, and all these positions lead to a component that is built into the product. Taken together, all these positions with the information they contain on the component form the bill of material.
The view of the where-used list can be described as follows:
- All n where-used list positions can be reached from a component, and all these positions lead to a product in which the component is used. Taken together, all the positions of the where-used list with the information they contain on the product form the where-used list.
The most important attributes that have to be administered for a bill-of-material position are:
- Product ID (the product identification); this is an item ID Component ID (the component identification); this is an item ID Quantity per, that is, the number or quantity of components that is needed to produce a single unit of the product
- Sequential number of the position within the bill of material (for sorting and identification purposes) Operation ID for which the component is needed (see Section 17.2.6)
- Lead-time offset, that is, the difference in time relative to the product completion date before which the components must be made available (see Section 1.2.3)
- Effectivity (dates) or effective dates (start and stop), that are the dates on which a component is to be added or removed from the bill of material; effectivity control may also be by engineering change number or serial number rather than date
Again, these are only the most important attributes for the elementary functions associated with the bill of material and where-used list. Additional attributes and even additional logistical objects must be represented for more complex applications, for example, bills of material for a product family with many variants. See also Chapter 7 and Section 17.3.
In historic and generic terms, the bill-of-material position ID (bill-of-material position identification) combines the product ID and component ID attributes. Today, it is more often the union of the product ID and sequential number of the position within the bill-of-material attributes, however.
The advantage of the second definition is that the same component can occur more than once in the same bill of material. The components may also be sorted into a logical order that does not correspond to the component ID. This does have the disadvantage that the number of possible components of a product is limited by the number of possible relative position numbers. In addition, to keep a certain degree of order, any “holes” must be filled in the order of relative position numbers. This can be done by first allocating every tenth number and then periodically reorganizing the numbering.
Aspects of computerized administration:
- Certain transactions enable whole or partial bills of material for one assembly to be copied to another assembly. There are also transactions that allow large-scale modifications to be carried out, e.g., by replacing a certain component with a different component in every bill of material (batch procedure running in background mode).
- Another algorithm periodically calculates the low-level code of all items. It can also check whether a multilevel bill of material is actually a product structure without loops. This test is often rather time consuming and is difficult to carry out online while administering the bills of material. See also Section 8.3.3.
Course section 17.2: Subsections and their intended learning outcomes
17.2 The Master Data for Products and Processes
Intended learning outcomes: Describe master data of products, components, and operations. Explain the data structure of item master, bill of material, and where-used list. Disclose the data structure of work center master data, the work center hierarchy, as well as for operation, routing sheet, production equipment, bill of production equipment, and bill of tools.
17.2.1 Product, Product Structure, Components, and Operations
Intended learning outcomes: Present the concept of master data. Explain the production order as a collection of master data. Describe a simple product structure.
17.2.1b The Intermediate Part
Intended learning outcomes: Identify the intermediate part used simultaneously as a component in higher-level products.
17.2.2 Item Master Data
Intended learning outcomes: Present the concept of the item master record. Describe the attributes of the technical information and the stockkeeping information of the item master record. Identify attributes of the item master record for information on costs and prices.
17.2.3a Bill of Material, Bill-of-Material Position, and Where-Used List
Intended learning outcomes: Present the concepts of the bill of material, of the bill-of-material position, and the where-used list.
17.2.3b Single-Level Bill of Material, Multilevel Bill of Material, and Summarized Bill of Material
Intended learning outcomes: Differentiate between the single-level bill of material, the multilevel bill of material, and the summarized bill of material.
17.2.3c Single-Level Where-Used List, Multilevel Where-Used List, and Summarized Where-Used List
Intended learning outcomes: Differentiate between the single-level where-used list, the multilevel where-used list, and the summarized where-used list.
17.2.3d The Bill-of-Material Position and the Where-Used-List Position as a Logistical Object
Describe the bill-of-material position and the where-used-list position as logistical objects. Identify its most important attributes.
17.2.4 Work Center Master Data
Intended learning outcomes: Present the work-center business object. Describe the attributes of the work-center master record relating to capacity, concerning costs, and for calculating the lead time.
17.2.5 The Work Center Hierarchy
Intended learning outcomes: Present the concepts of workstation and cost center. Explain the work center hierarchy.
17.2.6 Operation and Routing Sheet
Intended learning outcomes: Present the operation business object in association with the routing sheet. Describe its attributes. Identify the work center where-used list.
17.2.7 Production Equipment, Bill of Production Equipment, and Bill of Tools
Intended learning outcomes: Present the concepts of bill of production equipment and bill-of-production-equipment position as well as production equipment where-used list. Produce an overview on collective tool, bill of tools, bill-of-tools position, and tool where-used list.
