Conducting FMEA for a Robot Palletizer

Purpose of This Guide

To provide a structured, systematic approach to identifying potential failure modes in a robot palletizer, evaluating their effects, and prioritizing actions to reduce risks and enhance reliability.

SECTION 1: INTRODUCTION TO FMEA

🔹 What is FMEA?

FMEA (Failure Mode and Effects Analysis) is a proactive tool used to identify potential failure modes of components or processes and analyze their effects on overall system performance.

🔹 Types of FMEA:

• Design FMEA (DFMEA): Focuses on the design of the system.
• Process FMEA (PFMEA): Focuses on the processes involved in operating or assembling the system.

For a robot palletizer, Process FMEA is most applicable, but we can also consider Design FMEA for mechanical/electrical/software failures.

SECTION 2: OVERVIEW OF THE ROBOT PALLETIZER SYSTEM

🔹 System Components:

1. Robot Arm (FANUC, ABB, KUKA, etc.)
2. End-of-Arm Tooling (EOAT): Grippers, vacuum cups
3. Conveyor Feed System
4. Sensors (Position, Object Detection)
5. Control System (PLC/HMI/Robot Controller)
6. Safety System (Safety PLC, Emergency Stops, Light Curtains)
7. Pallet Dispenser / Conveyor Outfeed
8. Power Supply / Pneumatics / Hydraulics (if any)

SECTION 3: STEP-BY-STEP FMEA PROCEDURE

🔧 Step 1: Assemble a Cross-Functional Team

• Maintenance Engineer
• Controls Engineer
• Robot Programmer
• Safety Officer
• Production Supervisor
• Quality Engineer

Step 2: Define Scope and Function

Scope: FMEA for the operation of the robot palletizer in a packaging line. Function: To automatically pick boxes and stack them on a pallet based on pre-defined patterns.

Step 4: Identify Failure Modes, Effects, and Causes

Build an FMEA table with the following columns:

• Process Step
• Failure Mode
• Effect of Failure
• Severity (S)
• Cause of Failure
• Occurrence (O)
• Current Controls
• Detection (D)

RPN = S × O × D

• Recommended Action

SECTION 5: RISK PRIORITY NUMBER (RPN) AND ACTION PLANNING

🔹 RPN = Severity × Occurrence × Detection

High RPN indicates higher risk. You should prioritize:

• RPN > 150: Critical – immediate action required
• RPN 80–150: Medium – plan corrective actions
• RPN < 80: Monitor

SECTION 6: RECOMMENDED ACTIONS

For each high-priority failure mode:

• Review root causes (use 5-Why analysis)
• Implement control upgrades (e.g., better sensors, logic interlocks)
• Add detection systems (e.g., current sensors, torque feedback)
• Improve operator SOPs and training
• Update maintenance schedules

SECTION 7: FOLLOW-UP AND VERIFICATION

After implementing actions:

1. Review updated FMEA with reduced O and D values.
2. Calculate revised RPN.
3. Monitor system performance.
4. Schedule next FMEA review (every 6–12 months or after major changes).

SECTION 8: TOOLS AND RESOURCES

• FMEA Template (Excel or software like APIS IQ, PTC Windchill, or ReliaSoft XFMEA)
• IEC/ISO 60812 – Standard for FMEA
• Training for team on severity, occurrence, detection rating scales

SECTION 9: FINAL NOTES

• Document all assumptions clearly.
• Use version control for FMEA document.
• Integrate FMEA with your safety risk assessment and maintenance planning.

Example Summary of One Failure Mode

Failure Mode: EOAT fails to pick box

• Effect: Production stops
• Cause: Vacuum loss due to worn cup
• Current Controls: Vacuum pressure sensor
• RPN: 240 → High
• Action: Add predictive maintenance for vacuum system, install dual-sensor verification