Bill of materials
A BOM (English: parts list or bill of materials ( BOM) ) is a structured arrangement of objects or a list of components of a larger object, particularly of products (products) or modules or an assembly. A bill of material is a structured arrangement of parts or assemblies that are required for the production of another parent assembly. A bill assigns the components according to their structural properties. The function of the parts is irrelevant. BOM information is one of the most important data structures, which must have production companies: You ultimately serve to order the correct material (see needs assessment ) and / or to remove the camp, if a particular product is to be manufactured. In series production, process cost accounting and other control systems BOMs for retrograde actual fuel consumption calculation are used. Using BOM is the completeness of a system delivered in individual parts verifiable.
BOM structure and BOM usage
BOMs can be either according to their formal and structural unit (see below) or differ according to their purpose and area of use, eg Development BOMs, Production BOM, procurement BOMs or spare parts lists. This has the consequence that the product-related BOM data are stored multiple times and inconsistencies between the application parts lists are available. This leads to delays and problems in the process. The company creates not only significant administrative expenses, but this, there may also be technical problems or errors relating to product safety (see Product Safety Act ) and thus may affect the product liability. Therefore, in particular large companies are working on integrated and consistent BOM concepts. The focus is on a product-specific, technical bill, which is complemented by discipline- specific data. In this bill all users access to the company, but each have different access rights and an application- specific view of the BOM data.
Demarcation and overlap
BOMs are different recipes so far as they relate to discrete final products, they usually indicate what material is needed to produce 1 piece of the final product ( for example, 1 phone) to produce. Formulations, however, relate mostly to a certain quantity of the final product (for example, 1 kg cake). In foundries, one speaks of Gattierungslisten, which refers to the material composition of a melt. In the woodworking industry is referred to as timber lists, lists of materials in the construction industry.
Increasingly, the term BOM ( bill of materials ) is also found in the German language. The closer translation for BOM parts list, however. BOM relates generally to material descriptive lists, so it can, for example, a purchase requisition be meant.
In contrast to the parts list that emanates from the finished components, describes a work plan the production process in terms of the individual steps and the end sections to complete the part with the corresponding standard times ( setup time, run time, etc.). By appropriate assignments BOMs and routings can be connected together. A bill of position is assigned to a specific work plan item and / or vice versa.
Reference
A bill of decomposed an object from top to bottom. The converse of this view is referred to as reference or part -used list.
BOM structure or BOM types
In the literature, usually the basic types of quantities overview BOM, the BOM structure, the BOM, the BOM variants as well as the complex bill can be distinguished. The distinction relates primarily to the concrete representation on the screen or in a printout. Computer systems usually store BOM information in the form of the BOM, since it can be generated by vertical BOM all other required types and the maintenance effort is lowest. For complex products, which are produced in flow production (eg automotive industry) are often found also the BOM structure which sets out to generate modular bills of material and use of funds.
If one considers a specific product structure in the form of a tree structure:
P | ------- | 1x | 1x E1 B | ------- ------ | 1x | 1x | 2x E1 E2 E3 P: Product, B: Module, E1, E2 and E3 items so ask yourself the individual display modes as follows:
Quantity overview BOM
The amount overview BOM (English: "quantity synopsis parts list " ) lists undifferentiated as resolved BOM quantities required for the product directly to ( the performance of assemblies in the quantities overview BOM is not recommended). Example, the BOM for the product P:
By multiplying the amounts required to be produced to the amount of the product results in the so-called order BOM.
Structure BOM
A structure BOM (English: "structural parts list " ) has all assemblies, components and raw materials of a product and shows the composition of a product over all production stages in tabular form. It corresponds in its information content of the product structure. The quantities refer, depending on the agreement on the overall product on a lot or each unit of the parent part, explained by the example for the product P:
BOM
Modular BOMs (English: "unit list" ) are characterized by the fact that only one level of the product structure is considered: Assemblies receive their own BOMs that are used in the parts lists of parent groups, in turn, explains the example for the product P:
Product P
Module B
Variant BOM
In a variant BOM (English: " variant parts list " ) are 199-1:2002-03 multiple BOMs summarized on a form conforming to DIN, in order to perform various objects together with a generally high proportion of identical ingredients ( → Variant (product) ).
Complex BOM
Called The complex bill, also selection BOM or maximum BOM, is a form of variant BOM, in which all variants of a product or assembly are mapped together. To distinguish the variants of each other and to be able to assign the parts and assemblies in a single specific product variant, they must be provided with product-related attributes. These attributes are characteristics that describe the product accurately. A particularly effective way of attribution is the specification of an algebraic expression that refers to a set or subset of product variants. This assumes an algebraic product definition (Product encryption) with the help of features. Depending on what product it is, characteristics may affect the amenities, features, colors, materials or geometric, physical or chemical properties of a product. The features may among themselves either have only a loose relationship or form a structure in the form of an algebraic Association. This type of product definition can be found mainly in industries that produce complex and varied products. So in the automotive industry, the vehicles are described by a variety of characteristics ( features), which can be selected with the help of product configurators. Accordingly algebraic complex BOMs in use with many manufacturers. Depending on the specific shape of the product definition they differ then in the type of attribution ( → Variant Management).
Disposition BOM
The MRP BOM provides information about the disposition order. The parts are grouped at the lowest use and can be scheduled at the same time. A transfer of structure in planning bills of material is possible.
Multiple BOM
If the composition of a material can change lot size dependent, ie from a certain batch size to alter the quantities of one or more materials or new and additional components, this material BOM is converted into a multiple BOM. There are thus formed alternatives to the original bill. These are also referred to as a variant BOMs.
Transfer to other structures
From a BOM structure a BOM or a Gozintograph can be generated. Also can be generated from a structure BOM turn module parts lists; in the latter case, however, is not always ensured that the generated module parts lists are unique if the kits occur at different points in the product. Such transfers are not possible with the amount BOM, since there intermediate structures such as assemblies are hidden. The amount BOM, however, can be easily converted into a corresponding parts used list, which is often sufficient for a simple material requirements planning.