1. Workstation Design A. H. Mehrparvar, MD
Occupational Medicine department
Yazd University of Medical Sciences

2. Tools/Methods of Workstation Design
Anthropometry
Design Guidelines
Design Tools
There are several methods available for employees to use to setup workstations. Here are three areas that your workers can use for this purpose.

3. آنتروپومتری (Anthropometry)
Anthropos: انسان
Metrin: اندازه گیری یا سنجش
اندازه گیری ابعاد بدن انسان

4. هدف ارگونومی
طراحی ایستگاه یا پست کاری
متناسب با ویژگیهای فیزیکی و روانی کارگر

5. عدم رعایت اصول ارگونومیک در طراحی ایستگاه کاری
ایجاد وضعیتهای بدنی نامناسب هنگام کار
ایجاد بیماری

6. آنتروپومتری تفاوت بین دو جنس: مردها درشتتر از زنها
تفاوت در نژادهای مختلف:
نژاد آمریکایی در برابر آسیای جنوب شرق
تفاوت در سنین مختلف

7. People Are Different
Age Differences
Height Differences

8. صدکها بیان ابعاد آنتروپومتریک بر اساس صدکها
صدک پنجاهم، صدک پنجم و صدک نودوپنجم
صدک پنجم: 5٪ جمعیت کوچکتر از آن (= میانگین – 65/1 انحراف معیار)
صدک پنجاهم = 50٪ جمعیت کوچکتر و 50٪ بزرگتر از آن (= میانگین)
صدک نود و پنجم= 5٪ جمعیت بزرگتر از آن (= میانگین + 65/1 انحراف معیار)

9. بین صدک پنجم زنها و صدک نودوپنجم مردها
طراحی ارگونومیک بر اساس صدکها
طراحی تمامی ابزارها، تجهیزات و وسایل
برای گستره ای ازجمعیت
بین صدک پنجم زنها و صدک نودوپنجم مردها

10. شعار آنتروپومتری
وسایل و تجهیزات در حد دسترسی کوچکترین فرد قرار داشته باشند و با بزرگترین فرد تطبیق داشته باشند.

11. Acceptable/Unacceptable Work Positions
The concept that we are trying to reinforce here is that work needs to be in front of the employee. We need to design tasks in this manner. Reaching behind the body or working with the upper arm raised should be avoided.

12. Effect of Workstation Design on Posture
In this slide you can see the effects of work station design on posture. If this were a task where a person was placing chicken parts in totes or removing products from a conveyor you could see the impact of orientation and height. Totes placed too high can cause poor hand and wrist postures. If it is too high it can also cause poor arm postures as well.

13. Reach/Work Envelopes
These pictures show reaches for employees. The first picture shows the overhead shot of a worker at a work station. It defines acceptable reaches and work zones for people.
The next shot shows the side view for a seated person. It shows the acceptable reaches for a person who has to grasp an object. You will notice that both pictures express the reaches in arcs.

14. Optimal Work Zone
Here is another diagram that shows you the ideal work zone on a table or work surface. This is where most work should be done while in a seated posture.

15. Work Surface Heights
These two diagrams show the ranges for work station heights for both seated and standing work. As you will notice the heights vary based on the type of task being performed.

16. Work Surface Heights
Here is another example of work surface height guidelines. You can find these type of guidelines in several textbooks or other references.
Activity 2
How tall should you make an offline rework station? It involves some fairly detailed cuts to salvage as much breast meat as possible. If workers are working out of totes, where would you locate them so that they are easy to reach.

18. Issues in Workstation Design
Avoid static loads and fixed work postures
Reduce cumulative trauma disorders risks
Work height at ~50 mm below elbow
Give employee an adjustable chair
Use feet as well as hands
Use gravity, don't oppose it
Use two-handed motions rather than one-handed

19. Pivot motions about the elbow
Use the preferred hand
Keep arm motions in the normal work area
Let the small woman reach; let the large man fit

20. Goals of Workplace Design and Layout
Maximize performance and minimize hazards:
Minimize postural stress and fatigue (e.g. due to static loading) --- risk factor for work-related injury
Provide reach capability
Anthropometry
Minimize motion times and error rates
Work measurement

21. Often a major task of ergonomists
Strong relationship between productivity of a workers and their comfort
Primary objective: accommodate the worker
An uncomfortable workplace results in increased energy demands, fatigue, decreased worker performance, and occupational injuries

22. General considerations
Clearances, reaches, and manipulations (conserve momentum, use gravity when you can)
Visual and auditory demands
Environmental (noise, lighting, temperature, vibration) and organizational factors (such as contact with workers, supervisory control)
Posture changes

23. Workstation Types
Sit
Needed items can be reached, assessed, and handled within the seated workplace
Items handled are approximately 6” above and 16” in front of the worker
No large forces, no weights greater than 10lbs
Fine assembly, data entry, etc.

24. Stand No proper knee clearance Object weight >10lbs
Frequent high, low, or extended reaches
Frequent movement between stations
Requires downward forces
Optimal height of the hands
Elbow-light assembly, writing, packing
Waist-downward and sideward forces

25. Sit/Stand Repetitive operations
Multiple tasks are performed but are of sufficient duration that benefit from sitting
Design in postural flexibility

26. Benefits of sitting over standing
Delays the onset of fatigue (weight is taken off the legs, lower energy requirements, lower cardio-respiratory demands, avoid unnatural body postures)
More stability in the task
Allows for the use of foot controls
Pitfalls of prolonged sitting
Negative effects on the curvature of the spine
Disruption of body functions (blood flow, breathing, etc.)
Weakened abdominal muscles

27. Adjusting the workplace
Why is it important?
People vary in size and capability, accommodate individual comfort and usability, provides for possibility in changes in posture
How do you do it?
Adjust the workstation
Layout, Location (ht), Orientation
Adjust the person
Chair, Footrests, Armrests
Adjust the work piece
Jigs, clamps
Adjust the tools
Design the size, weight, material, use tool balancers

28. Use preferred hand for reach and grasp motions
Dominant hand is 10% faster for reaching and more accurate
Dominant hand/arm is about 5-10% stronger
About 10% are left hand dominant
Preferred hand should be used for dangerous or critical work
Allow for change-off to non-dominant hand for non-critical work, thus proving rest and recovery