2.1 BOM Lines, Line Types, and Component Configurations
Key Takeaways
- Bills of Materials (BOMs) govern discrete manufacturing by defining structural parent-child relationships, whereas process manufacturing uses formulas with co-products, by-products, and batch balancing.
- The five D365 SCM BOM line types (Item, Phantom, Pegged supply, Vendor, and Dimension group) control how Master Planning and production order estimation explode demand and consume inventory.
- Phantom BOM lines dissolve intermediate subassembly boundaries during order estimation, injecting child components and route operations directly into the parent production order without generating separate production orders.
- Total component consumption combines variable consumption (scaled by order quantity and per-series) with constant consumption, constant scrap, and variable scrap percentage.
- BOM lines support dynamic product dimension inheritance (Configuration, Size, Color, Style) and site-specific validity date windows for engineering phase-in and phase-out.
2.1 BOM Lines, Line Types, and Component Configurations
In Microsoft Dynamics 365 Supply Chain Management (D365 SCM), Bills of Materials (BOMs) form the engineering and operational backbone of discrete manufacturing. A BOM specifies the complete hierarchical structure of raw materials, subassemblies, parts, and packaging required to assemble an end product.
Understanding how BOM headers, BOM versions, and individual BOM lines interact is critical for passing the MB-330 exam and designing robust manufacturing solutions.
1. Discrete Manufacturing Architecture vs. Process and Lean
D365 SCM segregates production methodologies into three distinct operating models based on the Production type field configured on the Engineer FastTab of the Released Product:
- Discrete Manufacturing: Governed by Bills of Materials (BOMs) and Routes executed via Production Orders. Items are distinct, countable physical units (such as machinery, electronics, and vehicles) that can be assembled, disassembled, and repaired.
- Process Manufacturing: Governed by Formulas and Recipes executed via Batch Orders. Items are blended, mixed, or chemically transformed (such as liquids, bulk solids, paints, and pharmaceuticals). Formulas support ingredient potency, catch-weight handling, variable batch sizing, and the simultaneous creation of co-products and by-products.
- Lean Manufacturing: Governed by Production Flows and Kanbans. Material movement and replenishment are pull-driven based on takt time without production work orders.
Navigation Paths
- BOM Master Maintenance:
Product information management > Bills of materials and formulas > Bills of materials - Released Product BOM Lines:
Product information management > Products > Released products > Action Pane > Engineer tab > BOM group > Lines - Visual BOM Designer:
Product information management > Products > Released products > Action Pane > Engineer tab > BOM group > Designer
The BOM Designer provides an interactive graphical tree view of the finished good. It allows functional consultants and engineers to visually navigate multi-level product structures, drag and drop components across subassembly tiers, align components to routing operations, and analyze operational lead times.
2. BOM Line Types
Each line on a BOM must be assigned one of five Line types, which instructs Master Planning (Planning Optimization) and the production estimation engine how to source, consume, and cost the component:
| Line Type | Order & Inventory Behavior | Master Planning (MRP) Treatment | Typical Operational Use Case |
|---|---|---|---|
| Item | Deducts stocked inventory from warehouse via picking list. | Generates planned purchase, production, or transfer orders. | Standard raw materials, purchased hardware, or pre-built stocked subassemblies. |
| Phantom | Dissolves subassembly node during order estimation. Injects child lines into parent order. | Never plans orders for the phantom parent; explodes net requirements directly to child lines. | Transient engineering subassemblies built on-line but never stocked in inventory. |
| Pegged supply | Directly creates a child production or purchase order linked to parent order. | Generates pegged supply orders linked directly via parent lot ID (InventRefTransId). | Custom made-to-order subassemblies or dedicated parts synchronized to a specific parent run. |
| Vendor | Generates an external subcontract purchase order linked to a routing service operation. | Plans subcontract purchase order requirements for outside vendor processing. | Subcontracted plating, painting, heat-treating, machining, or vendor-supplied tooling. |
| Dimension group | Dynamically resolves component variant dimensions from parent finished good. | Plans specific variant SKU requirements based on inherited dimension parameters. | Configurable products where components inherit color, size, style, or configuration from parent. |
Operational Deep Dive on Key Line Types
- Phantom BOMs: Engineering departments frequently group components into logical subassemblies that are never placed into warehouse inventory. When a production order is estimated, D365 SCM explodes the phantom: the phantom parent item disappears from the production BOM, and its child components and route operations are promoted directly to the parent production order. This eliminates unnecessary reporting as finished, warehouse putaway, and picking transactions.
- Pegged Supply: Used when subassembly inventory must not be commingled with general warehouse stock. Estimating the parent order immediately generates a dedicated child production order (for manufactured items) or pegged purchase order (for purchased items). The finished output of the child order is reserved directly for the parent production order upon completion.
- Vendor Subcontracting: Configured with an outside service item and vendor account. Estimating the production order generates a linked subcontract purchase order, automating outside processing tracking and cost capitalization.
3. Consumption Calculations and Scrap Handling
D365 SCM provides precise mathematical controls on BOM lines to scale material consumption and account for production waste.
Variable vs. Per-Series (Constant) Consumption
- Variable Consumption: Consumption scales proportionally with the order batch size. The formula is:
- Per (Series): Specifies the base parent unit quantity against which the consumption quantity applies (default is
1). If an adhesive requires 250 mL per 50 finished units, enter Consumption =0.25 Land Per =50. - Constant Consumption: Consumed as a fixed quantity for the batch regardless of the order volume. Ideal for machine setup materials, primer coats in dipping vats, or sacrificial calibration test coupons.
Constant vs. Variable Scrap
Material scrap on BOM lines is divided into two distinct parameters:
- Constant Scrap: A fixed physical quantity lost during initial machine setup, tooling run-in, or calibration, completely independent of batch size (e.g., 5 feet of steel ruined during lathe chuck alignment).
- Variable Scrap: Scrap expressed as a percentage of net consumption that scales linearly with order volume (e.g., 3% metal swarf or cutting waste).
Total Gross Line Consumption Formula
[!IMPORTANT] Constant scrap is added before the variable scrap percentage is calculated. For example, if an order requires 100 net units, constant scrap is 10 units, and variable scrap is 10%, the total gross demand is $(100 + 10) \times 1.10 = 121$ units.
4. Product Dimensions and Inheritance on BOM Lines
When producing configurable items (using Product dimension groups: Configuration, Size, Color, and Style):
- Fixed Dimensions: The BOM line explicitly hardcodes a specific component variant.
- Dimension Inheritance: On the BOM line Setup tab, enabling dimension inheritance allows child components to automatically inherit matching dimensions (such as Color or Size) from the parent finished good during order creation.
- Storage and Tracking Dimensions: While BOM lines dictate physical items and product dimensions, storage dimensions (Site, Warehouse, Location) and tracking dimensions (Batch number, Serial number) are determined by the item default order settings and warehouse reservation hierarchies.
5. Site-Specific BOMs and Validity Dates
- Multisite BOM Architecture: A BOM Header can be assigned to a specific Site, or left blank to serve as a shared template across all corporate facilities. If assigned to a site, all component lines must consume inventory from that site.
- Line Validity Dates (From date / To date): Individual lines feature effectivity dates. This enables engineering teams to execute component phase-in and phase-out on specific dates directly on the BOM header without requiring a new BOM version.
Exam Tips and Common Traps
- Phantom vs. Pegged Supply: Phantom dissolves the subassembly node and injects lines into the parent order without generating a child production order. Pegged supply explicitly generates a dedicated, linked child production order.
- Constant Scrap Scaling: Constant scrap does not scale when production order quantity changes. Variable scrap always scales proportionally with volume.
- Dimension Group Line Type: Used when component variants must resolve dynamically based on parent product dimensions, avoiding redundant static BOM lines.
A manufacturing engineer is configuring a multi-level BOM for an industrial air compressor. One of the subassemblies, the motor bracket subassembly, is assembled directly on the main production line without ever being stocked in the warehouse or planned as an independent inventory item. Which BOM line type should the functional consultant recommend?
A custom bicycle manufacturer loses exactly 3 feet of steel tubing during initial machine clamping and chuck alignment on every production order, regardless of batch size. Additionally, high-speed cutting operations cause a consistent 4% metal swarf loss across total cut volume. How should the functional consultant configure scrap on the BOM line?
A company manufactures commercial pumps across two manufacturing facilities: Site 1 in Seattle and Site 2 in Chicago. At Site 1, an locally sourced impeller (Item IMP-01) is used, whereas at Site 2, an imported impeller (Item IMP-02) is used due to regional vendor contracts. Both facilities produce the identical finished pump product number. How should the functional consultant configure the BOM architecture to support this requirement with minimum administrative overhead?