Poka Yoke Concepts in Design Automation Renukaprasad Belgur

Inadvertent Mistakes - Poka Prevention - Yoke

Poka Yoke - Fail Safe POH-kah YOH-keh - means "fail-safing" or "mistake-proofing” “Poka” – Inadvertent mistake “Yoke” – Prevention Concept by Shigeo Shingo (1909 ~ 1990) – World’s leading expert on Mfg Practices – Shingo Prize – Lean Mfg Practices A methodology to Detect & Prevent causes of Defects ZQC – (Zero Quality Control) Most mistakes – committed by workers / errors in the production systems Feedback control and action system at the error stage Hi-Tech Gears Limited – Manesar, Haryana

Poka Yoke Principles Elimination Eliminate the possibility of Errors. Redesign of the Process or Product s – No need to inspect Replacement Substitute a more Reliable Process for the existing one. - Use of Robots or Automation Elimination Replacement 2 1 3 Mitigation 5 Mitigation Minimizing the effect of Error. - Protection, Safety Devices Facilitation Facilitation Make work easier to perform such as color coding, combining steps,.. 4 Detection Detection Detect error before further processing. Software interlocks which notifies an Operator for wrong inputs.

Product s & Services Design Principles - Fundamental Basic Functionality Safety Poka Yoke (Mistake Proofing) Ergonomic Design Simplicity Flexibility Robustness & Reliabile Ease of Use Ease of Maintainability ….. Product s & Services

Design Principles - Examples

Design Principles – Innovative

Road Crossing Solution

Poka Yoke Design - Examples

Poka Yoke Solutions - Examples

Errors@Work – Examples Circular Saw - Safety

Errors@Work – Examples Missing Parts Forgetting to assemble a part – Screws, Washers, labels, etc., Misassembled Parts Misassembly – loose parts, upside down, not aligned – Ex: Brackets (Reverse), seals not aligned, screws (Loose), Labels (Upside Down) Incorrect Processing Disposing of a part rejected at test to the wrong pile Incorrect Parts Retrieving and assembling the wrong part from a model mix selection – seals, labels, brackets, cses…

Fail Safe Assembly - Turbochargers Concept of FailSafe – Prevention & Detection Devices Guided Part Picking Verification of the picked part Verification of the Assembly Interlocking of checking systems Elimination – Eliminating the chance of error Facilitation – Guidance Methods to minimise error Mitigation – Lessen the effect of the error Flagging – Methods for capturing all defects prior to shipment Replacement Elimination Mitigation 2 1 5 Facilitation Detection 3 4

TurboCharger - Assembly Line

Assembly Line - Electrical Switchgear

Assembly Line – Yesteryears

Engine Assy Line – Workstations

Engine Assy – Engraving Station Inspn.

Typical Schematic - Engine Assembly Line 110 Work Stations 3000 I/O’s 14 HMI’s 80 Profinet Nodes 80 ASI Nodes 4 Barcode Printer 12 Vision System 5 Servo Systems 11 Nut runner stations 1 Engraving unit

Poka-Yoke – RH, LH Axle Bearing Inspn Upper bearing counting result PLC OK Ethernet Network Light Camera 1 Camera 2 Not OK Detecting RH, LH & Counting Lower Brg Balls Counting Upper Brg Balls

RFID – Typical Configuration Ethernet S7-300 PLC Profinet Profinet RFID Controller RF170C RFID Controller RF180C Read/Wright Head RF310R Read/Wright Head RF310R Data Carrier, 32kB RF350T Data Carrier, 2 kB RF360T

Fail Safe Devices – Poka Yoke Light Guided pick Devices Presence of Thread Sensors Presence of Component Sensors Vision System – Shape, Dimension, Orientation, etc., Laser Distance Sensors – Resolution >2microns Auxiliary equipment interlocks Software interlocks – Proceed to next station lock Component Check - Go – No Go Gauges with sensor Torque Sensors – Nut tightening Balancing check – Assembly Check Manual angular alignments – Checking using encoders

Laser Sensors Application Areas Reference & Diff thickness measurements Distance Measurements Positioning Profile measurements Level Measurements Material deformity measurements

Intelligent Systems – for Assembly

Pick Light Sensors

Fail Safe – Poka Yoke Approach 100% On-time delivery irrespective of variants Flexibility in Assembly line Consistency in Output with high Quality Best in class Ergonomics (man material movement) High Safety Standard Compliance Zero accidents, less fatigue, maxi efficiency Built in Sequential disciplined work approach - HMI No missing Parts / Parts pick sensing Vision check failsafe through Camera Quick changeover (< 1 min) Part Identification Integration of each station – Ethernet Data Acquisition, transfer, storage & analysis

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