Ergonomics - Operator Compatibility

Transcription

1 Ergonomics - Operator Compatibility Guidance for the designer, supplier, and user Doug Sten, PhD, CSP, CMSE, CEA Machine Safety Consultant Pilz Automation Safety Canton, Michigan USA

2 Presenter Doug Sten, Ph D, CSP, CMSE, CEA is a Safety Consultant with Pilz Automation Safety. Dr. Sten has degrees in Safety Engineering, Safety Management, Behavioral Science and is a Certified Safety Professional with a specialty in Product Safety, Certified Ergonomic Analyst and a CMSE - Certified Machinery Safety Expert, by TÜV Nord. He has over 25 years in the plastics machinery industry employed as a consultant; a global product safety manager for an OEM and a corporate safety director for a plastics container manufacturer. He has over 20 years participating on US and international safety standards committees. He has worked for Pilz since January D. Sten Ergonomics 2

3 Objectives What is ergonomics? What standards are available for guidance? Why is it so important for design safety? What percentile of men/women do we consider? Who will be working with, or operating, the machine? What tasks will be performed on the machine? Is there some type of recognized checklist? What fundamental applications can be served? D. Sten Ergonomics 3

4 What is ergonomics? Simply put: Designing to one s needs, taking into account one s physical and mental abilities and limitations in relationship to the demands of the machine, job and the work environment. D. Sten Ergonomics 4

5 Really? Most people look like this, but Some designers think people are shaped like this D. Sten Ergonomics 5

6 Design review D. Sten Ergonomics 6

7 Anthropometrics - Overview Selected body dimensions (without shoes) in inches for males/females D. Sten Ergonomics 7

8 Where do you stand? Where: = 69.1 in. σ (standard deviation) = 2.70 in. Z (factor) = 2.06 in. (98th percentile) Population percentile = (2.06 x 2.70) = = in. 98th percentile male is in. tall without shoes. D. Sten Ergonomics 8

9 How do we measure down? To calculate a percentile between 0 and 50: Percentile = - (Z x σ) 25 th = 69.1 (2.70 x.67) = D. Sten Ergonomics 9

10 Two hand controls Depressing issues Three major ergonomic designs to be considered in the use of palm buttons: Cup/ring guards Palm button location Button forces D. Sten Ergonomics 10

11 CTDs are a real pain Cup/ring guards: Prevent anti-bridging and unintentional operation slightly higher than the plane of the palm buttons Can result in ergonomic problems Operators use the finger tips/heels of the palms to activate buttons, creating high stress on the fingers and palms D. Sten Ergonomics 11

12 Location location location Palm button location Palm buttons located at, or near, waist height Palm buttons should be oriented at approximately the same angle as the forearm in order to minimize wrist deviations Button forces Typical palm buttons require depression of 1 cm (0.5 in) to be engaged Palm button engagement forces must not exceed the physical capability of operators (typically less than 2.25 kg / 5 lb.) D. Sten Ergonomics 12

13 The Force be with you... or not No force start buttons swipe controls (keep your gloves) Reposition palm buttons vertically removal of ring guards more inline with natural biomechanical movements. (Actually using the palms of your hands) D. Sten Ergonomics 13

14 Humans vs Machines Humans excel at: Sensitivity to a wide variety of stimuli Ability to react to unexpected, low probability events Ability to exercise judgment where events cannot be completely defined Adaptability to changes Perception of patterns and making generalizations Machines excel at: Performing routine, repetitive or very precise operations Exerting great force, smoothly and with precision Operating in environments that are hostile to humans or beyond human tolerance Being insensitive to extraneous factors Doing many different things simultaneously D. Sten Ergonomics 14

15 Let s go mining Critical questions when designing for operator compatibility: What does the individual have to do to operate the machine? How high should a work surface be? Standing/sitting? Can machine jams be safely and efficiently cleared? How will machine set-up or servicing tasks be performed? How will the machine be loaded and unloaded? Will there be room to perform maintenance efficiently? What machine guarding designs are most compatible? D. Sten Ergonomics 15

16 Proactive vs Reactive D. Sten Ergonomics 16

17 Show of hands Hand and wrist postures The following positions depicted below are risk factors D. Sten Ergonomics 17

18 Working shoulders down Arm and shoulder positions Postures below are considered to be risk factors D. Sten Ergonomics 18

19 A head above 99 percentile (EC) Standing height Definition Standing erect, distance from the standing surface to the top of the head Small Female Large Male North America 60.8 (154.4 cm) 74.6 (189.5 cm) European 60.3 (153.2 cm) 74.0 (188.0 cm) Asian 58.3 (148.1 cm) 70.9 (180.1 cm) Latin American 58.4 (148.3 cm) 70.4 (178.8 cm) D. Sten Ergonomics 19

20 Workstation design Sample applications Criteria Dimension Description A. Work Height Hands; precision work Light assembly Heavy work Adj ( cm) Fixed 44 (110 cm) Adj ( cm) Fixed 38 (95 cm) Adj (71 99 cm) Fixed 34 (85 cm) Distance from standing surface to hand work height for fine hand manipulations or visually intensive tasks Distance from standing surface to hand work height for tasks requiring force exertion < 10 lbs (4.5 kg) Distance from standing surface to hand work height for tasks requiring force exertion > 10 lbs (4.5 kg) B. Reach 19 (47.5 cm) Maximum reach to grasp hand work C. Display height Pref. Adj ( cm) Distance from standing surface to middle of viewable portion of display screen Fixed 60 (160 cm) Rotate 45 degrees up/down from vertical position is preferred, with horizontal adjustment D. Foot clearance depth Min. 6 (15 cm) Depth from front of any obstruction D. Sten Ergonomics 20

21 Keep it in the comfort zone Frequent reaches should be nominally made within cm (14-18 in) from the center of the shoulder front edge of the table Occasional reaches should be made within cm (22-26 in) Avoid reaches over 65 cm (26 in) D. Sten Ergonomics 21

22 Take a Stand Elbow Height is defined as that distance between the elbow and floor when the arm is bent 90 degrees at the elbow and is resting alongside the body. Note: 1. For light work or weights (forces < 1 kg/2 lb) or visually exacting work, raise the work surface above elbow height (5-10 cm/2-4 in) and provide padded rests for forearm 2. For normal or medium work or weights (forces < 4.5 kg/10 lb), work surface height should be below elbow height (2-4 in) 3. For heavy work requiring large downward or upward forces or weights (forces > 4.5 kg/10 lbs), lower the work surface to cm (4-8 in) below elbow height D. Sten Ergonomics 22

23 Line up card The following are brief descriptions of each Hit List item: Wash rag: Condition of extreme wrist bending, or any posture you would use to wring out a wash rag. Elbows out: Posture in which the elbow is out, away from the body often a compensation for a bend that the wrist is not capable of performing, resulting in the elbows winging out to the side. Shoulder too high/too low: Posture in which the shoulders are raised or dropped, most often a result of work locations being too high or too low. Hungry head: Awkward neck postures, most commonly seen when the employee is searching for visual information. D. Sten Ergonomics 23

24 The hits keep coming Butts up: A condition of bending over, or flexing the body forward. Twist and shout: Twisting at the neck or back while performing work activities. Horizontal distance: A condition of working far away from the body, either in front or to the side. Sit vs. stand: Condition in which the working position, either seated or standing, is inappropriate for the job. D. Sten Ergonomics 24

25 ... and coming Bad vibes: Condition in which the employee is exposed to any noticeable vibration. Contact: Condition in which the employee is exposed to hard or sharp parts of equipment that put pressure on soft body tissues. D. Sten Ergonomics 25

26 Proactive approach to safe design D. Sten Ergonomics 26

27 Start to finish 1. Establish ergonomic design specifications 2. Educate the engineering team 3. Manage constraints 4. Leverage existing design systems 5. Right questions to the right people 6. Validate designs, share success D. Sten Ergonomics 27

28 1. Establish ergonomic design specifications Manufacturers will often describe their equipment as ergonomic when in reality, no study or objective verification has been conducted to support the claim. Don t rely on suppliers to tell you that their products and equipment are ergonomically designed can lead to the dark side. Ergonomic design criteria be defined and measurable. Examine related safety standards; attend professional workshops; and/ or contact national safety organizations. D. Sten Ergonomics 28

29 2. Educate the engineering team Remember: Technology is advancing by leaps and bounds Design engineers should not waive proper ergonomics training because they had a class or two in college critical mistake Design engineers may perceive ergonomics applications to be of minor importance Make the ergo statement clear and hold people accountable/responsible D. Sten Ergonomics 29

30 3. Manage constrains Reduce risk with a cost vs benefit analysis: Avoid design paralysis relying on previous design based on perceived effectiveness and time savings Work as a change agent to keep past design issues fresh in minds and suggest alternative options D. Sten Ergonomics 30

31 4. Leverage existing design systems Ergonomics applications are often ignored by design engineers Risk assessment is integral in identifying hazards and related exposures Create accountability, assign responsibility and act on each accordingly D. Sten Ergonomics 31

32 5. Right questions to the right people Avoid Monday morning quarterback design decisions Conceptual and design review phases are the best times to get involved with design and recommend changes not when it s assembled. D. Sten Ergonomics 32

33 6. Validate designs, share successes Avoid reinventing the wheel with each design project Don t replicate bad designs Share experiences, good and bad learn from both. Learn as an organization and as a designer, an end user. D. Sten Ergonomics 33

34 National standards and other resources ANSI B 11 TR1-2004: Ergonomics Guidelines for the Design, Installation and Use of Machine Tools ISO 6385: Ergonomic Principles in the Design Work Systems Various Ergonomic Publications: e.g. Human Factors in Engineering & Design, Humantech, and Engineering Physiology-Bases for Human Factors / Ergonomics to name a few D. Sten Ergonomics 34

35 Ergo Check-up--Example D. Sten Ergonomics 35

36 Quiz Three good reasons to have ergonomic applications be an integral part of the engineering design review process? When integrating ergonomics into a piece of machinery, where/when do you start? Standing on the shop floor, what should be the range, in inches, regarding the height of a HMI located on the operator s control station? What is one effective ergo design for two hand controls application? D. Sten Ergonomics 36

37 Remember To Err is Human... To Forgive is Design D. Sten Ergonomics 37

38 CMSE, InduraNET p, PAS4000, PAScal, PASconfig, Pilz, PIT, PLID, PMCprotego, PMD, PMI, PNOZ, Primo, PSEN, PSS, PVIS, SafetyBUS p, SafetyEYE, SafetyNET p, the spirit of safety are registered and protected trademarks of Pilz GmbH & Co. KG in some countries. We would point out that product features may vary from the details stated in this document, depending on the status at the time of publication and the scope of the equipment. We accept no responsibility for the validity, accuracy and entirety of the text and graphics presented in this information. Please contact our Technical Support if you have any questions. Doug Sten, PhD, CSP, CMSE, CEA Pilz Automation Safety, L.P Commerce Blvd. Canton, MI USA Tel.: Fax: Keep up-to-date on Pilz