6.9 Picking, kitting & line release discipline

Kitting transforms generic inventory into committed “Work in Progress” (WIP). It represents the digital assignment of specific material lots to a specific demand (Work Order). Accurate kitting is fundamental to a smooth production run; if operators have to search for missing parts or decipher unclear labels, the line stops. The goal is to provide a comprehensive, verified kit that allows assembly to proceed without interruption.

Picking: the physical transaction

Picking should be a system-validated procedure. Relying on digital scans helps eliminate visual sorting errors.

• The Scan Logic:
  • The Target: The Warehouse Management System (WMS) directs the operator to a specific storage location, specifying the Manufacturer Part Number (MPN) and the required Lot (following First Expired, First Out (FEFO) rules).
  • The Action: The operator scans the Bin Location label, then the Part ID barcode.
  • The Validation:
    • If the scans match the requirement, the quantity is deducted from the bin and transferred to WIP.
    • If the scan fails (e.g. incorrect Lot or Revision), the system should halt the transaction. Operator overrides should be restricted to maintain data integrity.
• Quantity Management:
  • Full Reels: The complete reel must be picked whenever possible. Cutting tape must be avoided unless necessary for a split-build.
  • Exact Count: For high-value or highly controlled items (e.g. CPUs, custom modules), the count must be verified precisely.
  • Bulk/Passives: Inexpensive components must be issued by weight or as full strips/packs to minimize handling time. The labor cost of manually counting dozens of inexpensive resistors often exceeds the value of the components themselves.

Kitting & verification (the “staging” gate)

After picking, materials are consolidated in the Staging Area prior to line release.

• The Kit Cart Preparation:
  • The physical materials on the cart must be organized to logically match the SMT machine setup (e.g. sequencing reels to align with feeder slots 1 through 20).
  • ESD Compliance: The kit cart must function as an Electrostatic Protected Area (EPA) and be properly grounded.
• High-Value (A-Part) Verification:
  • For critical components, a two-person validation step should be considered.
  • The Protocol: The Picker stages the part, and a Quality Lead or secondary operator countersigns or systemically verifies the critical line items against the Bill of Materials (BOM).
• The “Clean Kit” Release:
  • The Goal: Release kits to the floor only when they are complete and clearly documented.
  • Documentation: Standard documentation must be included with the kit, such as the Pick List, relevant Assembly Drawings, and any approved Deviation or Substitution authorizations.

Exception handling: shortages & substitutions

In a real-world environment, production may occasionally begin with known shortages. This must be managed transparently.

• Managing Known Shortages:
  • The Protocol: If a kit is released to the floor with a shortage, the missing item must be highlighted clearly (e.g. in RED) on the physical paperwork and it must be ensured it is digitally flagged in the Manufacturing Execution System (MES).
  • The Goal: A situation where a line operator unexpectedly discovers a missing part mid-run must be prevented.
• Managing Substitutions:
  • The Protocol: If an alternate component is authorized for use, the Work Order BOM must be formally updated in the ERP to reflect the change before the material is issued.
  • The Risk: If the BOM specifies “Part A” but the warehouse issues “Part B,” the traceability record is fundamentally broken.

Engineering Practice

The handover from the Warehouse to Production represents a transfer of ownership. When Production signs for the kit, they assume operational accountability for those materials.

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Recap: Picking, Kitting & Line Release Discipline

Parameter	Requirement	Value / Action	Condition / Document
Picking Validation	System-validated scan of location and part.	Scan bin location, then part ID. Transaction halts on mismatch (incorrect Lot/Revision).	WMS directs to specific Location, MPN, and Lot (FEFO).
Quantity Issuance	Issue by full reel, exact count, or bulk method.	Full reels (default). Exact count for high-value items. Bulk/weight for inexpensive passives.	As per BOM and component classification (A-Part vs. standard).
Staging & Verification	Kit cart prepared as an EPA; critical parts verified.	Organize to match SMT setup. Two-person verification for high-value items.	Kit cart grounded. Verification against BOM by Picker and Quality Lead.
Line Release	Release only complete, documented kits.	Include Pick List, Assembly Drawings, approved Deviations/Substitutions.	Kit is complete. Documentation is physically and digitally attached.
Exception Handling	Manage shortages and substitutions with system integrity.	Shortages: highlighted (e.g., RED) on paperwork and flagged in MES. Substitutions: ERP BOM updated before material issuance.	Prevents mid-run discovery of missing parts. Maintains traceability.