1.28 Kitting, FIFO & Shortage Management

Kitting is the discipline that keeps a factory floor flowing, ensuring the exact right parts from the exact right traceable lots arrive at the exact right time. By linking every kit to a frozen BOM/AVL snapshot and adhering to strict inventory rules, kitting transforms material logistics from a scramble into a reliable choreography.

1.28.1 The Perfect Kit: Traceability and Accuracy

A controlled kit is not a pile of parts; it is a traceable package locked to a specific product definition. Accuracy beats speed during the picking process.

Kit Fundamentals

• Locked to a Snapshot: Every kit must be tied to a BOM/AVL revision that was current at the time of picking. Any Engineering Change Notice (ECN) issued afterward triggers a kit review/freeze.
• Traceability Mandate: Every line item must have a Unique ID (UID), linking it to the specific Lot/Date code logged at receiving. No "loose" or unlabeled handfuls are permitted.
• MSD and ESD Control: Sensitive materials must maintain their chain of custody. MSD reels stay sealed or in a DRY-CAB until the moment of loading. All parts travel in shielding totes/bags.

Issuing Rules: FIFO vs. FEFO

The choice of inventory method depends on the material's shelf life risk:

• FIFO (First In, First Out): Used for standard components, PCBs, and hardware. Use the oldest received material first, unless an engineering request dictates otherwise.
• FEFO (First Expiry, First Out): Used for chemistries (paste, flux, adhesives). Issue the lot that expires soonest, ensuring enough life remains for the planned run.

Picking Protocol

The process must be system-driven to ensure accuracy:

1. Verify & Scan: Scan the Work Order (WO), then scan the UID of every item picked. The MES must validate the PN – Location – Lot and flag incorrect revisions or off-AVL parts.
2. Count & Record: Use scales or counters to verify quantity. Record the issued quantity and the expected remainder.
3. Final Label: The completed kit card lists the WO, variant, revision, and all UIDs, serving as the final inventory manifest.

1.28.2 Crisis Control: Shortages and Deviations

When the materials plan fails, structured triage prevents a crisis from turning into a warehouse full of unproductive Work In Process (WIP).

Shortage Triage (DNS vs. BT)

Shortages must be classified to determine the right action:

• DNS (Do-Not-Start): If critical items (ICs, bare boards, unique connectors) are missing, DNS the WO. Do not start a partial build that will immediately starve the line or clog the WIP area.
  • Triage A (Critical): Unique IC, PCB, high-value module – DNS.
• BT (Build-Through): If only non-blocking items (standard hardware, labels, shields) are missing, you may BT with Production/Engineering sign-off and a clean re-touch plan for the missing parts.
  • Triage B (Conditional): Mechanical/hardware that can be installed later – BT with plan.

Maintain a Shortage Board (digital or physical) showing WO, PN, quantity missing, ETA, and owner for clear, continuous escalation.

Substitutions and Waivers

The rule is clear: No "close enough."

• If an alternate part is needed and is Not on the AVL, a formal Deviation/Waiver is mandatory. This requires sign-off from Process/Quality Engineering (PE/QE) and potentially Design.
• The waiver must confirm form, fit, function, test limits, and compliance. Document the decision on the kit card and ensure machine test recipes are updated before loading the deviated part.

1.28.3 Line-Side Management and Reconciliation

The line-side supermarket must be calm, not crowded. Clean close-out is mandatory for maintaining inventory accuracy.

Supermarket Discipline

• Min/Max: Use Min/Max levels tied to usage rates (takt time) or Kanban two-bin systems for high-volume consumables.
• Shelf Standard: Enforce one PN per slot. Ensure lot tags face outward, and no gray bins or unlabeled "misc" storage is allowed.
• Aging Control: If a staged kit sits > 24 – 48 hours unstarted, MSDs must be returned to DRY-CAB or resealed, and the entire kit must be re-validated before release.
• Load Scan: The machine must scan the UID to tie the specific Lot/Serial to the program.

Kit Close-Out

At the end of the run, the kit must be closed cleanly:

1. Count-Back: Count back and scan remaining reels/trays/tubes to update the quantity remaining in the MES.
2. MSD Management: Reseal any opened MSDs with fresh HIC/desiccant or park the reels in the DRY-CAB. Update the floor-life timer in the system.
3. Scrap: Scrap all chemistries (paste/flux) that have violated their open-time or expiry rules.
4. Variance: Any mismatch between the MES expected remainder and the scanned count-back requires a Variance Ticket for investigation.

1.28.4 Oversight and Efficiency Metrics

Managers drive stability by measuring the process and targeting the largest source of inefficiency first.

Metric	Focus
Kitting Accuracy (%)	Right line items / Total line items (Target: ≥ 99.8%)
DNS Hours	Lost production hours due to critical shortages (Target: 0)
Kit Age (days)	Time from kit pick to start of production (Shorter is better for risk control)
Supermarket Service Level (%)	Stockouts vs. Demand (Reflects Kanban/Min-Max health)
Substitution Rate (%)	Ratio of builds using non-BOM, waived parts

Common Traps – Smallest Reliable Fix

Trap	Symptom	First Move (The Reliable Fix)
Early Kitting of MSDs	HIC wet, floor-life timer wasted before start.	Pick MSDs closest to start time; rely on DRY-CAB staging.
Lot Mixing in Feeder	Traceability is broken; hard to isolate defects.	One lot per feeder; if mixed passives allowed, log both lots to the position.
Paste Inside Kits	Chemistry expires/condenses on arrival at the line.	Issue chemistries separately by FEFO; never stage them with components.
Partial Start on Shortage	WIP pile, line clog, cost increase.	DNS for critical shortages; BT only with a firm re-touch and test plan.