1. Motion Study and Work Design
Sections:
Basic Motion Elements and Work Analysis
Principles of Motion Economy and Work Design
Chapter 10
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

2. Definitions Motion study Work design
Analysis of the basic hand, arm, and body movements of workers as they perform work
Work design
Design of the methods and motions used to perform a task
Design of the work system
Includes:
Workplace layout and environment
Tooling and equipment used in the task such as workholders, fixtures, power tools, etc.
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

3. Basic Motion Elements
Frank Gilbreth – first to analyze and classify the basic motion elements
“Therblig”s – 17 basic motion elements
Spelled backward except for “th”
Basic building blocks of virtually all manual work performed at a single location (so the primary interest is the hand motions)
With modification, used today in several work measurement systems, e.g., MTM (Methods-Time Measurement)
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

4. Basic Motion Elements (continued)
“Therblig”s – 17 basic motion elements
Some of the motion element names and definitions have been revised
Involves both physical and mental elements
Although it is first used in production and logistics, the principles are also applicable to service industry.
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

5. 17 Therbligs
Transport empty (TE) – reach for an object with empty hand – today we call it “reach”
Grasp (G) – grasp an object by contacting and closing the fingers until control has been achived
Transport loaded (TL) – move an object with hand and arm – today we call it “move”
Hold (H) – hold an object with one hand
Release load (RL) – release control of an object
Use (U) – manipulate/use a tool
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

6. 17 Therbligs (continued)
Pre-position (PP) – position object for next operation
Position (P) – position object in defined location
Assemble (A) – join two parts
Disassemble (DA) – seperate multiple parts that were previously joined
Search (Sh) – attempt to find an object using eyes or hand
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

7. 17 Therbligs (continued)
Select (St) – choose among several objects in a group (hand-eye coordination is involved)
Plan (Pn) – decide on an action (a short pause or hesitation in the motions)
Inspect (I) – determine quality of object using the eyes
Unavoidable delay (UD) – waiting due to factors beyond worker control
Avoidable delay (AD) – worker waiting
Rest (R) – resting to overcome fatigue
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

8. Therbligs
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

9. Therbligs
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

10. Therbligs
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

11. Therbligs
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

12. Therbligs
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

13. Example
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

14. Classification of Therbligs
Effective therbligs:
Physical Basic Motion Elements:
Transport empty
Grasp
Transport loaded
Release load
Use
Assemble
Disassemble
Mental Basic Elements:
Inspect
Delay Elements:
Rest
Method study at the therblig level seeks to eliminate or reduce ineffective therbligs.
Ineffective therbligs:
Physical Basic Motion Elements:
Hold
Pre-position
Physical and Mental Basic Motion Elements:
Position
Search
Select
Mental Basic Elements:
Plan
Delay elements:
Unavoidable delay
Avoidable delay
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

15. Micromotion Analysis
The main idea of method study at the therblig level: seeks to eliminate or reduce ineffective therbligs.
Each therblig represents time and energy expended by a worker.
If task is repetitive, this will be performed many times. Then, it becomes meaningul to analyze therbligs.
Known as micromotion analysis
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

16. Micromotion Analysis
Analysis of therbligs that make up a repetitive task
Objectives:
Eliminate ineffective therbligs if possible
Avoid holding objects with hand – Use workholder
Combine therbligs – Perform right-hand and left-hand motions simultaneously
Simplify overall method
Reduce time for a motion, e.g., shorten distance
Checklists:
Checklist1 (discussed in the in class)
Checklist2 (given in the book – Table 10.3)
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

17. Principles of Motion Economy
Developed over many years of practical experience in work design
Guidelines to help determine
Work method
Workplace layout
Tools, and equipment
Objective: to maximize efficiency and minimize worker fatigue
Many people don’t understand why these principles are necessary, but you know that these principles are violated in work systems (think about your summer training).
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

18. Three Categories of Principles
Principles that apply to the use of the human body
Principles that apply to the workplace arrangement
Principles that apply to the design of tooling and equipment
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

19. Use of Human Body Most applicable to manual work
Design work to fully utilize both hands
The two hands should begin and end their motions at the same time to distribute the work equally to hands
Hand and arm motions should be symmetrical and simultaneous to minimize hand/arm-eye coordination
Avoid different independent motions of hands/arms
Design work to favor preferred hand
Work units should enter the workplace on the side of the worker’s preferred hand
Worker’s two hands should not be idle at the same time
except for the rest breaks
Don’t forget that not all tasks can be organized according to these principles.
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

20. An experiment A relatively simple task
Reaching, selecting, grasping, transporting, releasing
small parts.
Two types of containers
A rectangular bin
A bin with a tray
The worker performed the work cycle with each container using
Only the right hand
Only the left hand
Both hands performing symmetrical and simultaneous motions.
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

21. 0.72 sec / work unit 0.54 sec / work unit
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

22. Use of Human Body Utilize laws of physics
Method should consist of smooth continuous curved motions rather than straight motions with abrupt changes in direction
Although shortest distance between two points is a straight line
Because straight-line path sequence includes start and stop actions (accelerations and decelerations) consume worker’s time and energy
Use momentum (mass * velocity) to facilitate task
Carpenter using a hammer to strike a nail
Take advantage of gravity – Don’t oppose it
Method should achieve a natural rhythm of the motions involved
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

23. Use of Human Body
Use lowest classification of hand and arm motion (five classifications)
Finger
Finger and wrist
Finger, wrist, and forearm
Finger, wrist, forearm, and upper arm
Finger, wrist, forearm, upper arm, and shoulder
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

24. Movement of the fingers only as when picking up a cotton roll.
                                          II
Fingers and wrist motion as used when
transferring an instrument to the operator,
or manipulating a hand instrument.
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

25. Fingers, wrist, and forearm as when reaching for a handpiece.
III
Fingers, wrist, and forearm as when reaching for a handpiece.
                                         
IV      
The entire arm when reaching for supplies away from the work area, or to adjust the operating light.
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

26. V
The entire arm and shoulder as when turning around to reach for equipment from adjacent fixed cabinetry.
                                         
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

27. Use of Human Body
For using body members other than the hands, and arms
Minimize eye focus and travel
Minimize the distance between the object
Design method to utilize feet and legs where appropriate
Since they are stronger than arms
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

28. Workplace Arrangement
Design of the workplace
Locate tools and materials in fixed positions within the work area
Locate tools and materials close to where they are used
To minimize the distances to be covered
Locate tools and materials to be consistent with sequence of work elements
Decrease the time required for searching
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

29. Workplace Arrangement
Normal and maximum working areas in the workplace
Design for average user
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

30. Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

31. Illustration of First Three Principles
Poor arrangement of parts and tools in workplace
Numbers indicate the sequence of operations
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

32. Illustration of First Three Principles
Good arrangement of parts and tools in workplace
Numbers indicate the sequence of operations
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

33. Workplace Arrangement
Use gravity feed bins to deliver small parts and fasteners
Two types of bins used for small parts and fasteners in the workplace:
(a) gravity feed bin
(b) conventional rectangular bin
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

34. Workplace Arrangement
Use gravity drop chutes for completed work units where appropriate
Provide adequate illumination
Also color, constrast among items, location of the light source are important
A proper chair should be provided for the worker
Adjustable to the size of the worker
Seat height and back adjustments
Padded seat and back
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

35. Adjustable Chair for Workplace
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

36. Design of Tooling and Equipment
Workholding devices should be designed for the task
Hands should be relieved of work elements that can be performed by the feet using foot pedals
sewing machine
Combine multiple functions into one tool where possible
Pencils designed for writing and erasing
Perform multiple operations simultaneously rather than sequentially
Multiple-spindle drill presses to drill holes in PCBs
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

37. Design of Tooling and Equipment
Where feasible, perform operation on multiple parts simultaneously
Machines in a cake factory
Design equipment controls for operator convenience and error avoidance
Controls should be located within easy reach to minimize the body motions required to access them
Hand tools and portable power tools should be designed for operator comfort and convenience
e.g. tools that can accomodate both right-handed and left-handed workers
Mechanize or automate manual operations if economically and technically feasible
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.