Epicor BOM Strategy: How Assembly Settings Impact Jobs, Inventory, and Cost

When configuring a Bill of Materials (BOM) in Epicor, one of the most important decisions you will make is how to define subassemblies. The settings Pull as Assembly, View as Assembly, and Phantom BOM are frequently misunderstood, yet they directly impact job creation, inventory behavior, costing accuracy, and production visibility.

Selecting the wrong configuration can create unnecessary job complexity, distort cost rollups, or eliminate critical traceability. Selecting the right one ensures your Epicor manufacturing environment reflects how your operation actually builds products.

This guide explains how Pull as Assembly, View as Assembly, and Phantom parts function in Epicor, when each should be used, and how to align them with your manufacturing strategy.

What Is Pull as Assembly in Epicor?

Pull as Assembly determines whether a manufactured subassembly is built as part of the parent job or issued from stock.

This setting applies only to manufactured parts with a defined Method of Manufacture in Epicor.

Pull as Assembly OFF

When Pull as Assembly is not selected:

• The part is treated as a single material in the parent job

• No internal assembly record is created

• The system issues the completed subassembly from inventory

This configuration is best for make-to-stock subassemblies that are:

• Frequently reused

• Built independently of specific parent jobs

• Maintained as inventory

In this scenario, Epicor does not recreate the subassembly operations every time the parent job is released. Instead, it pulls from stock, keeping job structures cleaner and reducing production overhead.

This approach supports stable production environments where standard components are built in advance and consumed as needed.

Pull as Assembly ON

When Pull as Assembly is selected:

• Epicor creates a full assembly structure within the parent job

• Operations and materials from the subassembly’s method are included

• The subassembly is built as part of that job

This configuration is appropriate for make-to-order or engineer-to-order environments where the subassembly:

• Is unique to a specific job

• Is customized

• Is not normally stocked

Pull as Assembly increases job detail and production visibility, but it also increases complexity. It should be enabled intentionally, not by default.

What Is "View as Assembly" in Epicor?

View as Assembly controls visibility in the Epicor Bill of Materials. It does not change how the system manufactures or costs the part.

View as Assembly OFF

• The subassembly appears as a single line in the parent BOM

• Its internal materials are hidden from the parent view

This keeps the structure compact but limits transparency for planning and purchasing.

View as Assembly ON

• The materials within the subassembly are displayed in the parent BOM view

• Buyers and planners gain better insight into full material requirements

From a system perspective, enabling View as Assembly does not negatively impact costing, MRP, or job processing. It strictly improves structural visibility.

In most manufacturing environments, enabling View as Assembly is recommended because it enhances clarity without introducing risk.

What Is a Phantom BOM in Epicor?

A Phantom Part represents a manufactured structure that is not stocked as inventory.

When a part is defined as phantom and used in a Method of Manufacture, Epicor rolls its operations and materials directly into the parent assembly’s method. No separate job or stock record is created for the phantom component.

This is often used for logical groupings of materials that simplify engineering structure but do not represent a physically stocked item.

Key Characteristics of Phantom Parts

• Manufactured but not stocked

• No inventory quantity maintained

• Operations and materials are absorbed into the parent job

• No separate production tracking

Phantom parts are ideal when:

• The grouping is for design clarity only

• The component does not exist independently

• There is no need to track inventory or cost separately

System Restrictions

A part cannot be defined as phantom if it is:

• Purchased

• Stocked

• Lot-tracked

• Serial-tracked

These restrictions exist because phantom parts cannot maintain inventory attributes or tracking characteristics.

Choosing the Right Configuration

Understanding the practical difference between these options is essential.

Scenario	Recommended Configuration
Frequently reused subassembly kept in stock	Pull as Assembly OFF
Unique subassembly built per job	Pull as Assembly ON
Improve visibility of subassembly materials	View as Assembly ON
Logical grouping not stocked or tracked	Phantom BOM

The key distinction lies in whether the component:

1. Is stocked

2. Needs its own job tracking

3. Requires inventory visibility

4. Exists as a physical, independent item

Phantom BOM simplifies structure but removes separate tracking. Pull as Assembly controls whether the subassembly behaves as inventory or as part of the job. View as Assembly controls visibility only.

Operational and Costing Considerations

Configuration choices influence:

• Job structure complexity

• Material planning accuracy

• Inventory levels

• Production reporting

• Cost roll-ups

For example:

• Using Pull as Assembly incorrectly may create unnecessary jobs or prevent proper backflushing.

• Misusing Phantom BOM may eliminate needed traceability.

• Leaving View as Assembly off may reduce transparency for planning and purchasing teams.

These settings should align with the company’s manufacturing strategy, whether it is make-to-stock, make-to-order, engineer-to-order, or hybrid.

Final Thoughts

Epicor provides flexibility in how assemblies are structured, but that flexibility requires informed decision-making. Pull as Assembly, View as Assembly, and Phantom BOM each serve a distinct operational purpose.

When used correctly, they support cleaner job structures, better inventory control, and more accurate production reporting. When misapplied, they can create confusion in costing, planning, and execution.

Before implementing or modifying these settings, it is important to evaluate how your organization builds, tracks, and stocks components. Clear structure at the engineering level translates directly into cleaner production execution.