1.4 Master Data Model + SSOT Rules (BOM/Routing/Resources)

Master Data is the executable code of your factory. If the Bill of Materials (BOM) or Routing contains an error, the MES will flawlessly automate the production of a defect. Treat Master Data not as static documentation, but as a rigid configuration set that requires version control, validation gates, and cryptographic integrity.

Canonical Master Data Entities

A production process relies on four distinct data entities. Each entity must have a unique immutable identifier (Primary Key) to prevent ambiguity.

1. Bill of Materials (BOM)

• Definition: The hierarchical list of components and raw materials.
• Primary Key: PartNumber + Revision (e.g., PCBA-1001-Rev02).
• Constraint: A BOM must never be modified in place. Any change requires a new Revision ID.

2. Routing (Bill of Labor)

• Definition: The sequential list of operations, capable work centers, and standard times.
• Primary Key: RouteID + Revision.
• Constraint: Every Operation Step must map to a valid Resource Type.

3. Resources (Work Centers)

• Definition: Physical assets (Machines, Lines, Benches) or Logical groups (Test Stations).
• Primary Key: AssetID (Physical) or ResourceGroupID (Logical).
• Constraint: Resources must have an Active / Maintenance / Decommissioned state flag.

4. Recipes / Programs

• Definition: Machine-specific files (PnP placement files, Reflow profiles, ICT test scripts).
• Primary Key: ProgramName + Checksum (MD5/SHA256).
• Constraint: The MES must verify the machine loaded the exact program specified in the Routing.

Pro-Tip: Decouple the Engineering BOM (EBOM) from the Manufacturing BOM (MBOM). Engineering designs by function; Manufacturing builds by assembly step. The MES consumes the MBOM.

Synchronization Logic

The integrity of the system depends on the alignment of these entities. Use the following logic to enforce the "Digital Triad" (BOM + Route + Work Instruction).

• If BOM Revision increments (Rev A → Rev B) → Then Flag Routing for Mandatory Review. (New parts often change the assembly process).
• If Work Instruction Revision ≠ Active Routing Step Revision → Then Block Operator Login. (Prevent building to obsolete prints).
• If Recipe Checksum at Machine ≠ Checksum in MES Master Data → Then Trigger Electronic Interlock (Stop Line).

Lifecycle State Machine

Data must mature through defined states. Implement a strict State Machine to prevent premature or unauthorized usage of data on the shop floor.

State Definitions

1. Draft: Under construction. Visible to Engineers only. Action: Block from Production Orders.
2. Pending Approval: Locked for editing. Awaiting QA/Production Manager signatures.
3. Released (Active): The Single Source of Truth (SSOT). Available for scheduling.
4. Obsolete: Legacy data. Action: Block from new Orders. Retain only for historical genealogy.

Transition Rules

• If State = Released → Then Lock Record (Read-Only).
• If Modification is required → Then Create New Revision (Rev N+1).
• If Critical Quality Issue detected → Then Force State to "Hold" or "Obsolete" immediately.

Drift Controls & Reconciliation

Over time, the ERP (Financial view) and MES (Floor view) will drift apart without active policing. Implement these automated controls to detect and block drift.

1. Blocking Conditions

• Checksum Mismatch: Before releasing a Work Order, calculate the hash of the BOM+Route. If Hash(Order) ≠ Hash(MasterData) → Then Quarantine Order.
• Ghost Resources: If Routing specifies Resource_A but Resource_A is flagged "Decommissioned" → Then Block Scheduling.

2. Reconciliation Reports

Run a nightly comparison job between ERP and MES databases:

• Orphaned Parts: Items existing in MES BOMs but deleted/inactive in ERP.
• Unit of Measure (UoM) Conflicts: ERP uses "Each", MES uses "Meters". Action: Flag for manual correction.

Change Control: ECO & Flushing Strategy

Engineering Change Orders (ECO) introduce risk. You must define exactly how a change enters the production stream to avoid mixing revisions.

Effective Date Logic

• Immediate: Stop line. Purge all WIP. Setup new revision. (Use only for Safety/Critical Quality).
• Rolling (Flush): Allow current WIP to finish on Old Revision. Start new Orders on New Revision.

WIP Compatibility Logic

• If Change affects Form/Fit/Function → Then Purge WIP or Rework.
• If Change is Documentation Only → Then Allow WIP to complete.

Versioning Syntax Standard

Ambiguity kills traceability. Adopt a rigid syntax to distinguish prototype data from mass production data.

• Pre-Production: Use Decimal or Alphanumeric (0.1, 0.2, A, B).
• Mass Production: Use Integers (01, 02, 03).
• Rule: A change in a child component (Part A → Part B) always forces a revision increment of the parent assembly.

Final Checklist

Category	Metric / Control	Threshold / Rule
State	Production Gate	Only "Released" state is executable.
Integrity	Immutability	Released records are Read-Only (No "Edit", only "Revise").
Alignment	Triad Check	BOM + Route + WI revisions must match.
Drift	Nightly Reconciliation	0 Orphaned Parts; 0 UoM conflicts.
Recipes	Machine Control	Recipe Checksum in MES = Recipe Checksum on Tool.
ECO	WIP Handling	Defined "Flush" vs "Purge" strategy for every change.
Access	Approvals	Min. 2 Signatures (Eng + Quality) to Release Master Data.