One Assembly In SAP Business One, a item that is made up of several components — individual parts, sub-assemblies, and, if applicable, manufacturing resources. Via Production parts lists, production orders and optional disassemblies, SAP Business One maps the entire lifecycle of an assembly: from the definition of its composition through to manufacturing and Decomposition Back to components.
Context and meaning
Assemblies are the structural backbone of complex products. They enable multi-level product modelling – a top-level assembly can itself consist of sub-assemblies, which in turn have their own bills of materials. This creates the foundation for precise material requirements planning (MRP), clean cost accounting, and traceable production control.
The manufacturing of an assembly reduces the stock of components (OITM/OITW) and increases the stock of the finished assembly. The Production costs are comprised of the material costs of the components and invoiced resource costs – therefore, changes in component prices directly affect the product costs of the assembly.
Master data prerequisites
For the clean representation of an assembly, several master data levels must interact:
- Master data (OITM) Both the assembly and all individual parts and sub-assemblies must be set up as stock items.
- Production Bill of Materials (OITT/ITT1) A bill of materials of type „production" must be defined for each assembly. It contains all components with exact quantities and, if relevant, resources such as labour time or machines.
- Master Data Resources (ORSC) When manufacturing requires labour time or machines, these are stored as resources with capacities, costs, and cost accounts.
- Data integrity: The article type of an article that is already in use in a bill of materials can no longer be changed – a system lock against data inconsistencies.
Assembly manufacturing process
The manufacturing process runs in clearly defined steps:
- production order deposit Based on the assembly's bill of materials, a production order with status „Planned" generated.
- Release The order will be on status „Released" scheduled — the components will be reserved for production.
- Goods Issue (Dispatch of goods for production): The required components are withdrawn from the warehouse — manually or automatically via backflush upon completion. Component stocks (OITW) decrease accordingly.
- Route planning & Stages For complex assemblies, the process can be broken down into stages. This allows for targeted progress monitoring and the stage-by-stage release of resources (WOR4 — Process Sequence).
- Goods receipt from production: Once manufacturing is complete, the assembly is booked into warehouse stock – the inventory increases, and the production order is closed.
- Disassembly (optional): If an assembly is to be dismantled, a production order of type „Disassembly" is used. The inventory value is distributed to the recovered components.
MRP and Resource Planning
Of the MRP Assistant (Material Requirements Planning) takes into account the demand for assemblies – for example, from sales orders or higher-level bills of materials – and generates production order recommendations for the assembly and purchase requisitions for its components. Multi-level assemblies are resolved recursively: the demand for a final assembly automatically triggers demand for all sub-assemblies and their individual parts.
the Resource Capacity Planning complements material planning: The lead time of an assembly results from the processing times of the individual steps and the availability of the required resources. Careful capacity planning is crucial to avoid bottlenecks – especially with parallel production orders that share the same machines or workstations.
Practical tip
Maintain production bills of materials in as much detail as possible – especially resource allocation. A bill of materials containing only material components provides incomplete manufacturing costs and leads to variances in subsequent costing. For multi-stage assemblies, regular reconciliation of component prices is worthwhile: changes to a sub-assembly will automatically affect all higher-level assemblies.
Demarcation
Baugruppe in der Fertigung Sales Bill of Materials (Sales BOM) or a Assembly list (Assembly BOM). These are only dissolved at the point of sale and do not generate a physical manufacturing process – there is no production order, no resource booking, and no separate stock of the parent item. A true assembly, on the other hand, exists as an independent stock item, goes through a documented manufacturing process, and bears its own manufacturing costs. It also needs to be distinguished from a Bill of materials of type „Template", which merely serves data collection and has no storage effect.
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