The BOM Structure property defines the status of the component in the BOM. Define the default BOM structure values on the Bill of Materials tab in Document Settings. To change the BOM Structure, double-click the BOM Structure row in the Bill of Materials.
The BOM structure has five options:
- Normal
- Phantom
- Reference
- Purchased
- Inseparable
Normal
Normal is the default BOM Structure for most components.
Normal components:
- parent assembly determines the placement/participation in the BOM.
- are numbered and included in quantity calculations.
- have no direct influence on child components participation in the BOM.
Phantom
Phantom components are used to simplify the design process. They exist in the design, but are not line items in a bill of materials.
Phantom components:
- are not included in the Structured BOM.
- children appear in Structured BOM views
- are included in assembly mass calculations.
- are not numbered, and are not directly included in quantity calculations.
- the quantity of children is multiplied by the quantity of the phantom component.
Examples:
- Sets of hardware where the components are purchased and assembled separately, but are commonly used together (for instance screws, nuts, and washers).
- Installation Assemblies. When you want to focus on a certain section of an assembly, you can set other subassemblies as Phantom. Use Phantom to avoid working with a large assembly file.
Phantom Interaction with Normal, Inseparable, and Purchased Child Components
When a parent component is phantom, and has children that are normal, purchased, or inseparable, then:
- The BOM promotes the children in structured views to a higher level than the model structure dictates.
- The quantity of promoted child components is multiplied by the quantity of phantom parent components.
- The promoted child components are combined with any other matching components at that same assembly level.
- The order, sorting, and numbering of promoted child components is determined as if they were at the promoted level.
- If multiple phantom parent components exist, children are promoted until they reach a level where the parent is not phantom.
Reference
Reference Components are components that are used for construction geometry or add context to a design.
- are ignored in the BOM.
- are excluded from mass and volume calculations.
- are shown with a hidden line style in drawing views.
- are not numbered and are not directly included in quantity calculations.
- child components of the reference component are ignored in the BOM.
Examples:
- Construction elements such as a skeleton part or assembly for skeleton modeling.
- Visual enhancements, such as a tote filled with parts sitting on a desk. The tote is added for technical drawing/publication purposes. It is not a part of the actual design.
Purchased
Purchased components are components that are not fabricated.
Purchased components:
- are considered a single BOM line item, even though it is a part or an assembly. For example, an assembly marked as purchased is listed as a part in parts-only parts list.
- If the purchased component is an assembly, its children are not included in the BOM. Children are also excluded from quantity calculations in the BOM.
- have the normal child components of a purchased assembly included in a structured parts list, and numbered, but are hidden in parts-only parts lists.
Examples:
- Cylinders, pistons, or shock absorbers.
- Swing arms for LCD monitors.
- Hinges.
Inseparable
Inseparable components are generally assemblies where a component or multiple components must be physically damaged to separate them. Many manufacturing processes consider inseparable assemblies to be a single-line item like purchased components, but Inseparable assemblies are fabricated, not purchased.
Inseparable components:
- separates the assembly. Some component, or multiple components must be physically damaged.
- have one or more child components are considered part of the parent and are never tracked or revised separately.
- in a parts-only parts list, the inseparable assembly is treated as a part just like a purchased assembly.
- have an inseparable assembly that is treated as a standard assembly when it is documented in its own context.
Examples:
- Weldments, including assemblies that are glued or bonded.
- Riveted components fastened together with semipermanent fasteners that must be destroyed to separate the components.
- Assemblies where components have been press fit together, such as dowel pins pressed into a part.
Inseparable assembly with purchased children components
Inseparable components and purchased components have one difference in their behavior. In a parts-only parts list or BOM, all children of a purchased assembly are hidden. The assembly itself shows up as a line item in the BOM. For Inseparable assemblies, child components with a BOM structure of normal or inseparable components are hidden. Purchased child components that are inside an inseparable assembly are still displayed in the parts-only parts List.
Virtual components
Use the Create In-Place Component command to create a virtual component in an assembly. A virtual component is a component that does not require geometry or a unique file. Virtual components are treated as real components. They have a browser entry, and have properties such as quantity and part number.
Examples:
- Fasteners that you do not need to model.
- Bulk items such as gas, paint, or lubricant.
- Intangible bill of materials line items such as packaging or software.
If you delete all instances of a virtual part from the browser, the virtual component must be recreated using the Create In-Place Component command.