4.1 Digital Andon Systems

A traditional Andon system (lights on a pole) is a passive request for help; a Digital Andon system is an active subpoena for support. In a high-speed line, a "Red Light" that goes unnoticed for 10 minutes is 10 minutes of lost capacity that can never be recovered. The goal of Digital Andon is to convert "Line Down" events into Workflow Tickets with enforceable Service Level Agreements (SLAs).

The Taxonomy of Stops

Not all stops are equal. The system must classify the "Ask" immediately to route it to the correct department. Do not broadcast generic "Help" messages to everyone.

Material Call (Logistics)

• Trigger: Operator scans "Low Level" or Machine throws "Feeder Empty" alarm.
• Routing: Warehouse / Water Spider.

Maintenance Call (Equipment)

• Trigger: Machine Error Code (e.g., "Motor Fault") or Operator "Broken Tool" button.
• Routing: Maintenance Technician.

Quality Call (Process)

• Trigger: Consecutive Failures at AOI or Operator visual doubt.
• Routing: Quality Engineer / Line Lead.

Process Call (Bottleneck)

• Trigger: Cycle time exceeds target by > 15%.
• Routing: Shift Supervisor.

The Escalation Logic (The Timer)

The Digital Andon is a "Dead Man's Switch." If the primary responder does not react, the system automatically escalates to the next tier. This removes the social friction of "tattling" on a coworker; the system calls the boss, not the operator.

Severity & SLA Matrix

Define these rules in your MES configuration:

• Tier 1 (Responder): The Technician/Lead assigned to the line.
  • Response SLA: 5 Minutes.
  • Action: Must "Acknowledge" (Scan Badge) at the station.
• Tier 2 (Manager): The Area Manager / Engineer.
  • Trigger: If Tier 1 Status = "Open" > 15 Minutes.
  • Action: Receive Push Notification / SMS.
• Tier 3 (Executive): Plant Manager / Director.
  • Trigger: If Tier 1 Status = "Open" > 60 Minutes.
  • Action: Receive Email Report. (This is the "nuclear option").

Pro-Tip: Do not count "Response Time" as "Fix Time." Measure two metrics: "Time to Acknowledge" (Reaction speed) and "Time to Resolve" (Technical capability).

The Workflow State Machine

An Andon event is a ticket. It must traverse a defined lifecycle.

Open (Red State)

• Start: Event Triggered.
• Clock: Ticking. Line is likely Down.
• Andon Board: Flashing Red.

Acknowledged (Yellow State)

• Action: Responder scans badge at the terminal.
• Meaning: "I am here working on it."
• Clock: Escalation Timer pauses; Resolution Timer continues.
• Andon Board: Solid Yellow.

Resolved (Green State)

• Action: Responder selects Root Cause Code and closes ticket.
• Meaning: Production has resumed.
• Clock: Stopped.

Closure Rules & Reason Codes

You cannot improve what you do not categorize. Closing an Andon ticket requires a "Confession"—a mandatory data entry explaining why the line stopped.

The "Other" Ban

• Rule: Remove "Other" or "Misc" from the dropdown menu.
• Why: "Other" is a data black hole. Force users to select a specific category (e.g., "Feeder Jam," "Software Crash," "Missing Part").

Validation Logic

• If Duration > 10 Minutes AND Comment Field is Empty → Then Block Closure. Force the technician to type a brief explanation.
• If Responder ID = Operator ID → Then Flag for Review. (Operators should not be closing their own maintenance tickets).

Automatic vs. Manual Triggers

• Automatic (Hard Down): Connect the machine state (DI/O or OPC-UA) directly to the Andon.
  • Logic: If Machine State = "Error" > 30 Seconds → Then Auto-create Maintenance Ticket.
• Manual (Soft Stop): Touchscreen interface for the operator.
  • Logic: Operator presses "Quality Check." Line continues running (if safe), but Quality Engineer is summoned.

Final Checklist

Category	Metric / Control	Threshold / Rule
Routing	Targeted Alerts	Alerts go only to the relevant department (Logistics vs. Maint).
SLA	Auto-Escalation	If Ticket > 15 mins unacknowledged → Then Auto-alert Manager.
States	Acknowledgement	Distinct states for "Help Requested" (Red) vs "Help Arrived" (Yellow).
Data	Taxonomy	"Other" category banned. Specific Root Cause required for closure.
Input	Friction	One-touch activation for operators. No complex menus during a crisis.
Governance	Ghost Calls	If Auto-Andon triggers but Operator clears it instantly → Log as "Micro-stop" for analysis.
Visibility	Displays	Large overhead screens must refresh status in < 5 seconds.