Mastering the Tools of the Ergonomics Trade David Alexander, PE, CPE Auburn Engineers, Inc.

Transcription

1 Mastering the Tools of the Ergonomics Trade David Alexander, PE, CPE Auburn Engineers, Inc.

2 About Dave Alexander... Entrepreneur, Pioneer, Author, Inventor Auburn Engineers, Inc. Founder, President Since 1987 Consultant to industry & government Eastman Kodak 13 years experience Ergonomics Management Consulting Registered Professional Engineer Certified Professional Ergonomist Peer Recognition IIE - Fellow 1990, Ergonomics Division Award, 1986 HFES - IE Technical Group Award, 1993 Texts Industrial Ergonomics: A Practitioner s Guide The Practice and Management of Industrial Ergonomics Industrial Ergonomics: Case Studies Ergonomics Design Guidelines Applied Ergonomics - Case Studies Volumes 1, 2 & 3 Software & Technology etools Shop, etools Office, etools Design Patent Holder Pivotable Pommel Culinary Decorator Applied Ergonomics Conference Series Founder and Chair

3 THANKS TO OUR CLIENTS KELLWOOD who permit us to push the envelope of ergonomics around the world.

4 Mastering the Tools of the Ergonomics Trade Presentation Objective: To provide an overview of the tools available to an ergonomics practitioner for the evaluation of work Topics: 1. How much is too much? 2. What tools are available? 3. Using some common tools 4. Freeware 5. The next generation of tools 6. Questions/Answers

5 What Is an Ergonomics Job Evaluation? Look at these workers. Will their work result in injury? Lifting, carrying, use of hand tools, stooped postures and other issues will result in acute or overuse injuries. More importantly, can we predict which injuries will occur, how serious they might be, and at what frequency? Note that there are other safety and health issues as well. Credit: Grape Pickers, Lew Keller, US Post Office, St. Helena, CA (Works Project Administration Art Project 1932)

6 Tools of the Ergonomics Trade AIHA Ergonomic Assessment Toolkit ACGIH TLVs CTD Risk Assessment Metabolic Rate GM-UAW Ergonomic Checklist Liberty Mutual NIOSH Lifting Guide Occupational Repetitive Action OSHA Screening/VDT Checklists PLIBEL Rodger s Muscle Fatigue Assessment Strain Index Utah Back Compressive Force Washington State Caution & Hazard Zones, Lifting Calculator University of South Florida Ergonomics Analysis Methods Anthropometry Reach Envelope Percentiles Static Work Analysis Estimation of Metabolic Work Dynamic Work Analysis Washington Department of Labor & Industries Rapid Upper Limb Assessment RULA Rapid Entire Body Assessment REBA Rodger s Muscle Fatigue Assessment Whole Body Vibration ACGIH TLVs Liberty Mutual Manual Materials Handling Tools Utah Back Compressive Force NIOSH Lifting Guide

7 Tools of the Ergonomics Trade AIHA Ergonomic Assessment Toolkit gonomics/documents/ectoolkit.pdf University of South Florida Ergonomics Analysis Methods

8 Tools of the Ergonomics Trade Shop or Office? Anthropometric Musculoskeletal Physiological Sensory Environmental Size Special Populations Force Repetition Posture Fatigue Endurance Light Sound Heat Vibration Upper Extremities Low Back

9 Some Common Ergonomics Job Evaluation Tools Qualitative Quantitative Specialized: single body part Rapid Upper Limb Assessment - RULA ACGIH TLV for Hand Activity Ovako Working Posture Analysis - OWAS Revised NIOSH Lifting Equation Borg Scale for Rating of Perceived Exertion Lifting Index Strain Index Comprehensive: many risk factors; many body parts OSHA Checklists WISHA Checklists Rapid Entire Body Assessment - REBA Energy Expenditure Prediction Program 3D Static Strength Prediction Program Liberty Mutual Tables for Lifting, Carrying, Pushing & Pulling

10 Practitioner s Dilemma: What Tool to Use? How Many to Use? Rapid Upper Limb Assessment RULA Strain Index Liberty Mutual Tables for Lifting, Carrying, Pushing & Pulling Revised NIOSH Lifting Equation Rapid Entire Body Assessment REBA WISHA Checklist Screening: Qualitative Analysis: Quantitative

11 From the Grape Pickers: What do our ergonomics tools tell us? Rapid Upper Limb Assessment RULA Strain Index Investigate >7 Liberty Mutual Tables for Lifting, Carrying, Pushing & Pulling = 15.7 Revised NIOSH Lifting Equation Rapid Entire Body Assessment REBA WISHA Checklist = 32.6 Very High Risk Hazard Screening: Qualitative Analysis: Quantitative

12 Measuring Ergonomics Risk Factors 2 nd Generation Tools Qualitative Tools WISHA Screening Tool Visual Observations Semi-Quantitative Tools REBA & RULA ACGIH TLV for Hand/Arm Vibration Liberty Mutual MMH Tables Rogers Muscle Fatigue Assessment Quantitative Moore-Garg Strain Index NIOSH Lifting Guideline Anthropometry Tables

13 (WISHA) Washington Industrial Safety and Health Act Qualitative

14 WISHA - Awkward Posture No No No

15 WISHA - Awkward Posture (Not shown in graphic) Picking grapes requires bending knees to pick up box from ground X X X

16 WISHA - Hand Force -- Pinch X (Not shown in graphic) Picking grapes requires pinching, often in bent wrist postures X

17 WISHA - Hand Force -- Grasp X Carrying containers of grapes

18 WISHA - Highly Repetitive Motion Cutting grape stems X Not applicable

19 WISHA - Repeated Impact Not Applicable Not Applicable

20 WISHA - Lifting Analysis 45

21 Rapid Upper Limb Assessment (RULA) Semi-Quantitative

22 RULA Uses body posture diagrams and three scoring tables to quantify risk factors Considers Body Part Postures Arm and Wrist Neck, Trunk & Leg Muscle Use Force Demands

23 RULA - Rapid Upper Limb Assessment

24 RULA -- Total Grand Score Step 5: a) Cross reference Score C + Score D b) Use Table C to look up Grand Score

25 RULA -- Total Grand Score Step 5: a) Cross reference Score C + Score D b) Use Table C to look up Grand Score A B Upper arm 2 Lower arm 1 Wrist 3 Wrist twist 1 Neck 5 Trunk 4 Legs 2 Use Table A Posture Score A Use Table B Posture Score B 3 8 Muscle Force Score C Use Table C Grand Score Muscle Force Score D

26 RULA -- Action Levels Level 1 (Score of 1 or 2) Posture acceptable if not maintained or repeated for long periods Level 2 (Score of 3 or 4) Further investigation needed; changes may be required Level 3 (Score of 5 or 6) Investigation & changes required soon Level 4 (Score of 7) Investigation & changes required immediately

27 Rapid Entire Body Assessment (REBA) Semi-Quantitative

28 REBA - Rapid Entire Body Assessment

29 REBA Uses body posture diagrams and three scoring tables to quantify risk factors Considers Body Part Postures Neck, Trunk & Leg Arm and Wrist Muscle Use Force Demands

30 Activity Score - REBA Step 1: a) Score Group A: neck, trunk, leg; look up in Table A, add force load to get score A b) Score Group B: upper arm, lower arm, wrist; look up in Table B total in Posture Score B A Neck 3 Trunk 3 Leg 3 Use Table A Posture Score A Force/Load Score A B Upper Arm 1 Lower Arm 1 Wrist 1 Use Table B Posture Score B 1 Coupling Score B 1 2 Use Table C Score C 9 Activity 2 Final REBA Score 11

31 REBA -- Action Levels 1 2 or 3 4 to 7 8 to Negligible risk Low risk, change may be needed Medium risk, further investigation, change soon High risk, investigate and implement change Very high risk, implement change

32 RULA & REBA -- Summary Simple surveys that target upper limb and/or entire body MSD risks Good for screening large numbers of employees quickly Identifies if further analysis is needed (low thresholds most tasks are investigate )

33 Manual Handling Tasks NIOSH Lifting Guideline (Quantitative) Liberty Mutual MMH Tables (Semi-Quantitative)

34 Chosing The Right Model Frequency Biomechanical Physiological Psychophysical Load/Force

35 NIOSH Lifting Guidelines THE 1991 NIOSH EQUATION FOR THE DESIGN AND EVALUATION OF MANUAL LIFTING TASKS

36 H = horizontal distance from mid-point between ankles to hands. Weight = 45 lb. H = 9 inches V = 30 inches V = vertical distance of hands above floor. D = vertical travel distance A = angular displacement of load from sagittal plane (i.e. twisting). +10 when standing 9 D = 40 inches A = 30 degrees F = 1 lift/5 min. Dur = 10 hours C = Fair (small) F = average number of lifts during 15 min. C = quality of hand to object coupling. 35

37 Calculations 29 lbs Poor RWL = 51 x HM x VM x DM x AM x FM x CM X X X X X = Lbs. RWL = 51 X LI = Object Weight (L) RWL = =

38 Who Is At Risk? LI = Object Weight RWL LI = 1.0 LI = 2.0 LI = 3.0 DESIGN OBJECTIVE

39 elift (Visitors from 165 countries last year)

40 erula

41 ereba

42 Summary & Closing There are many ergonomics job evaluation tools. Knowledge and skills are required for their use. Interpretation is important. Different tools may provide conflicting results. Using the wrong tool can provide incorrect answers.

43 A 3 rd Generation of Ergonomics Tools Is Emerging A set of tools that work easily together. Screening and evaluation use similar data. The output is visual: Red, Yellow, Green An non-expert user can deliver quality results. Analysis leads directly to targeted, specific solutions. An analogy: 1 st Generation Bulky satellite telephone 2 nd Generation Cellular telephone 3 rd Generation Smart phone

44 Mastering the Tools of the Ergonomics Trade Questions/Answers