The BOM Structure property defines the status of the component in the BOM. BOM Structure has five basic options: Normal, Phantom, Reference, Purchased, and Inseparable.
The BOM Structure is by default set to the value defined on the Bill of Materials tab in Document Settings. You can override the structure to be Reference at the component instance level.
BOM Structure of Content Center library parts
By default, the BOM Structure is set to Purchased for all standard components. Custom components (components with a user-defined parameter) are set to Normal.
BOM Structure of iParts
All iPart components have a BOM Structure identical to the iPart Factory that generated them.
Normal
Normal is the default BOM Structure for most components.
Normal components have the following characteristics:
- Their placement/participation in the BOM is determined by their parent assembly.
- They are numbered and included in quantity calculations.
- They have no direct influence on their child components participation in the BOM.
Phantom
Phantom components are used to simplify the design process. They exist in the design, but are not distinct line items in a bill of materials.
Examples of phantom components are:
- Sets of hardware where the components are purchased and assembled separately, but are commonly used together (for instance screws, nuts, and washers).
- Installation Assemblies. For instance, 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 components have the following characteristics:
- They are ignored by the BOM.
- They are included in assembly mass calculations.
- They are not numbered, and are not directly included in quantity calculations.
- They influence the participation of their children in the BOM by promoting them in Structured BOM views. The children of a Phantom component are treated as siblings to the phantom component siblings, even though from a model structure standpoint, they are not.
- The quantity of their children is multiplied by the quantity of the phantom component.
Phantom Interaction with Normal, Inseparable, and Purchased Child Components
When a parent component is phantom, and it has children that are normal, purchased, or inseparable, then:
- The BOM promotes the children in structured views to a higher level than their 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.
Examples of Reference Components are:
- 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, where the tote is added for technical drawing/publication purposes. It is not a part of the actual design.
- They are ignored in the BOM.
- They are excluded from the mass calculations.
- They are not numbered, and are not directly included in quantity calculations.
- Child components of the reference component are ignored in the BOM.
- They are shown with a hidden line style in drawing views.
When a component has a BOM Structure of Reference, the BOM treats the component and all its direct and indirect children as if they do not exist. All components, that are a part of a Reference component, are excluded from quantity, mass, or volume calculations, regardless of their own BOM Structure value. Reference components also have special treatment in drawing views.
Purchased
Purchased components are components that are not fabricated.
Examples of Purchased Assemblies include:
- Cylinders, pistons, or shock absorbers.
- Swing arms for LCD monitors.
- Hinges.
Purchased components have the following characteristics:
- The component is considered a single BOM line item, whether 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.
- Normal child components of a purchased assembly are included in structured parts list, and numbered, but are hidden in parts-only parts lists.
Inseparable
Inseparable components are generally assemblies where a component or multiple components must be physically damaged to disassemble the assembly. Many manufacturing processes consider inseparable assemblies to be a single line item like purchased components, but Inseparable assemblies are fabricated, not purchased.
Examples of inseparable assemblies are:
- Weldments including assemblies that are glued or bonded.
- Riveted components fastened together with semi-permanent 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 components have the following characteristics:
- To separate the assembly, some component or multiple components must be physically damaged.
- 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.
- An inseparable assembly is treated as a standard assembly when it is documented in its own context.
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 are hidden. Purchased child components that are inside an inseparable assembly are still displayed in the parts-only parts List.