Poka Yoke Concepts in Design Automation

Renukaprasad Belgur

Inadvertent Mistakes - PokaPrevention - 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

Replacement

Elimination

Miti

gatio

n

21

5

Facilitation

Detection

3

4

Poka Yoke Principles

MitigationMinimizing the effect

of Error. - Protection,

Safety Devices

EliminationEliminate the

possibility of Errors.

Redesign of the Process or Product s

–

No need to inspect

FacilitationMake work easier to perform such as color coding, combining steps,..

ReplacementSubstitute a more Reliable Process for the existing one. - Use of Robots or Automation

DetectionDetect error before further processing. Software interlocks

which notifies an Operator for wrong inputs.

Design Principles - Fundamental

1. Basic Functionality

2. Safety

3. Poka Yoke (Mistake Proofing)

4. Ergonomic Design

5. Simplicity

6. Flexibility

7. Robustness & Reliabile

8. Ease of Use

9. Ease of Maintainability …..

Prod

uct s

& S

ervi

ces

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 PartsMisassembly – loose parts, upside down, not aligned – Ex:

Brackets (Reverse), seals not aligned, screws (Loose), Labels (Upside Down)

• Incorrect ProcessingDisposing of a part rejected at test to the wrong pile

• Incorrect PartsRetrieving and assembling the wrong part from a model mix selection – seals, labels, brackets, cses…

Fail Safe Assembly - Turbochargers

Concept of FailSafe – Prevention & Detection DevicesGuided Part PickingVerification of the picked partVerification of the AssemblyInterlocking 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

Eliminati

on

Miti

g

ation

21

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 Stations3000 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

PLC

Ethernet Network

Detecting RH, LH & Counting Lower Brg Balls

Light

Camera 1

Counting Upper Brg Balls

Camera 2

Upper bearing counting result

OK

Not OK

Data Carrier, 32kBRF350T

Read/Wright HeadRF310R

Read/Wright HeadRF310R

Data Carrier, 2 kBRF360T

RFID ControllerRF180C

Profinet

Ethernet

S7-300 PLC

Profinet

RFID ControllerRF170C

RFID – Typical Configuration

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

prasad@avasarala.com

Presentation material - © Avasarala Technologies Limited