BOM Setup & Part Specification¶
The Bill of Materials (BOM) is the foundational data structure for all costing in CostEngine. It defines the technical identity of the part and its physical composition.
Technical Specifications¶
| Feature | Description | Requirement |
|---|---|---|
| Part Number | Unique identifier for the component | Mandatory |
| Material Grade | Scientific/Trade name of the raw material | Mandatory |
| Dimensions | physical size (L x W x H or Diameter x Length) | Mandatory |
| Net/Gross Weight | Weights (finished/input) in kg | Mandatory |
| Process | Primary manufacturing process (e.g., CNC, Casting) | Mandatory |
| Tolerance | Required precision levels (e.g., ±0.05 mm) | Mandatory |
| Surface Finish | Coating or texture requirements | Mandatory |
| Sourcing Type | In-house, Bought-out, or Sub-contracted | Mandatory |
BOM Structure Logic¶
CostEngine captures parts in a hierarchical tree structure, where each part is decomposed into its individual components and sub-components.
1. Hierarchical Breakthrough¶
Each node in the hierarchy is a unique record with its own technical attributes. This creates a single source of truth for Engineering and Costing.
graph TD
Final["Final Part / Assembly"] --> A["Component A (Machined)"]
Final --> B["Component B (Treated)"]
Final --> C["Component C (Standard/BOI)"]
A --> A1["RM: Al 6061"]
A --> A2["Process: CNC"]
B --> B1["RM: Mild Steel"]
B --> B2["Process: Heat Treat"]
C --> C1["RM: Stainless Steel"]
C --> C2["Sourcing: Bought-out"]The Hierarchical Advantage¶
Adopting a structured representation at the component level provides critical downstream benefits:
- Design Reuse: Designers can directly reuse existing components (like "Component C") from the library instead of redesigning, reducing engineering overhead.
- Faster Costing: Each component carries its own price drivers (material, machine rate, processing). This enables an automatic roll-up to the final part cost as components are added.
- Impact Analysis: Any change at the component level (e.g., a material price hike or a shift from CNC to Casting) instantly reflects in the total cost and manufacturability assessment.
- Consistency: Standard components remain identical across products, significantly reducing variation and manufacturing errors.
Implementation Rules¶
- Immutable Identity: Once a quote is published (v1.0), the part specifications are locked for that version.
- Weight Precision: All weights must be handled with 4-decimal precision (e.g.,
0.1234 kg) to avoid rounding drift. - Sourcing Context: Costing logic shifts based on "Sourcing Type" (e.g., Bought-out items use supplier rates, In-house uses MHR).