Chapter 5: Workplace, Equipment and Tool Design Presented by Andira

Chapter 5 Focuses on: Design of Tools and Equipment to fit Human Constraints Work Processes Operations Work environment Tools

Goal of Chapter 5 Does FOCUS on: Principles of work design Check lists for design Does NOT focus on underlying theory of physiology and human limitations, (Can get that in: KIN 4135 Human Motor Control and Learning KIN 5132 Motor development

Key points Fit tools and equipment to operator Provide adjustability Maintain neutral postures Minimize repetitions Use “power grips” for high-force tasks Use pinch grips for precision tasks

Outline of Chapter 5 Anthropometry and design: Design for extremes, for average, etc. Principles of work design: workplace Focus on design of seating Principles of work design: machines and equipment Cumulative Trauma Disorders (CDT) Principles of work design: (hand) tools.

I. Anthropometry and Design Anthropometry: the science of measuring the human body, Ergonomics: designing the workplace, tools, equipment, work environment and operations to fit the human operator. Anthropometric data: Table 5-1(pg. 184) shows data on a typical human population; this data is invaluable in design.

Approaches to Design Design for Extremes: design to accommodate the max and min dimensions of the population, or perhaps the 5th to the 95th percentile. Design for Adjustability: make designs adjustable to fit different sized individuals. Design for the Average: design to suit the average person, and not be too bad for most people.

II. Principles of work design: workplace Use elbow height to determine work surface height. Adjust the work surface height based on the task Provide a comfortable chair Provide adjustability in the seat Encourage postural flexibility Provide Anti-fatigue mats for a standing operator Locate all tools and materials within the normal working area Fix locations for all tools and materials Use gravity bins and drop delivery Arrange everything to minimize motions

1. Use elbow height to determine work surface height

3. Provide a comfortable chair Example: Aeron Chair Images from: http://www.ultimatebackstore.com/

Being seated flattens the lordotic arch (lumbar region)

Balans chair: straightens pelvis

Encourage Postural Flexibility: gets blood supply to discs

    Exercise Ball Chairs

The bean bag chair

Ergonomic pros and cons of the bean bag chair Conforms to the shape of each person Moves with the person Relatively low cost ($80 - $200) Cons: Not suitable for office work – not enough structure to provide back support for computer or desk work, Hard for old people to get out of chair, Informal: not appropriate seating if you are having the Queen of England to tea.

Could this be the solution?

Other Bean Bag furniture Bean bag tables

7. Locate all tools and materials within normal working area

7. Locate all tools and materials within normal working area (cont)

III. Principles of work design: Machines and equipment Use a fixture (instead of the hand) Locate control devices for best accessibility and strength Use shape, texture and size to code controls Use proper control knob size, displacement and resistance Insure compatibility between controls and displays

VI. Cumulative Trauma Disorders (CDT) or repetitive motion injuries National Safety Council (1997) says that 15 – 20% of workers in key industries are at risk for CTD (meat packing, poultry, auto and garment industries) 61% of all occupational illnesses are associated with repetitive motions (butchering and manufacturing are worst) There are approximately 2 CTD claims per 1000 workers @ $30K pre case.

Cumulative Trauma Disorders are: Common Widespread in many industries Expensive Painful, Disabling Design work, tools and equipment to avoid them!!

Examples of CTD: Carpal tunnel syndrome Tennis elbow Bursitis Trigger finger

Carpal Tunnel Syndrome

Factors leading to development of CTD Excessive force Awkward or extreme joint motions High repetition Duration of work

Symptoms of CTD Pain Restricted movement Tissue swelling Numbness (if nerves are involved) CTD comes on slowly, gradual development, often ignored. CTD can lead to permanent disability

V. Principles of work design: (hand) tools Use power grip for tasks requiring force Use pinch grips for tasks requiring precision Avoid prolonged static muscle loading Perform twisting motions with elbows bent Maintain a straight wrist Avoid tissue compression Design tools to be used by either hand Avoid repetitive finger motions Use strongest working fingers: middle and thumb Design 1.5” handle diameters for power grips Design handle lengths to be a minimum of 4”

Grips: power, pinch, hook, press

9. Use strongest working fingers

10. Design 1.5” handle diameters for power grips Good grips products: originally designed for the handicapped, but good for everyone.

V. Principles of work design: hand tools (continued) Design a 3” grip span Design appropriately shaped handles Design grip surface to be compressible and non-conductive Keep the weight of the tool below 5 lbs. Use gloves judiciously User power tools instead of hand tools (e.g. screw drivers, etc) Use proper configuration and orientation of tools Choose a power tool with proper characteristics

12. Design a 3” grip span

13. Design Appropriately Shaped Handles

18. Use proper configuration and orientation of tools