1. Problem Solving Tools for Methods Engineering
Chapter 2
Problem Solving Tools for Methods Engineering

2. Our Text Book Website:

3. Outline for today A short history of Human Factors and Ergonomics,
Methods Engineering/Work Design
Example of Methods Engineering
Discussion of in-class exercise,
Approaches for both physical and “thinking” tasks,

4. A Short History of Human Factors and Ergonomics
Year
Event
1760
Perronet makes time studies
1820
Charles W. Babbage makes time studies
1832
Charles W. Babbage publishes On the Economy of Machinery and Manufactures
1881
Frederick W. Taylor begins his time study work
1901
Gantt develops the task and bonus wage system
1910
Gilbreth publishes Motion Study
1933
First Ph.D. granted in the United State in the field of industrial engineering from Cornell University
1949
The Ergonomics Research Society (The Ergonomics Society) founded United Kingdom
1957
The Human Factors and Ergonomics Society is founded United States
1970
Congress passes the OSHAct, Occupational Safety and Health Administration
1981
NIOSH lifting guidelines are first introduced
1990
Americans with Disabiities Act (ADA) is passed by Congress
1995
ANSI Z-365 Standard for Control of Work-Related Cumulative Trauma Disorders
2006
50th Anniversary of the Human Factors and Ergonomics Society

5. Methods Engineering Technique for: Decreasing cost per unit output.
Increasing production per unit of time.
Example: increasing the number of customers that can be handled per cashier by installing bar code readers.
Decreasing cost per unit output.
Example: decreasing total cost of each cell phone by reducing the number of parts and thus the labor hours required for assembly.
It is critical to look at impact on whole system.

6. Methods Engineering Focuses Primarily on improving productivity though (re)design of:
Motivation:
Incentives/rewards
Organizational
structure
Work Process
Work operations
Tools
(Products)
Work environment

7. Methods Engineering Often used synonymously with:
Corporate re-engineering
Work design
Operation analysis
The difference between these terms in the level of detail.
Big picture level
Detail level

8. Methods Engineering Select project Present and install method
I.D. product or service experiencing difficulties.
Get and present data
Study situation, take measurements to determine where difficulties really lie,
Analyze the data:
Figure out which of many problems are most critical
Develop ideal method(s)
Identify alternative approaches which may address most critical problems.
Present and install method
at the work site
Develop a job analysis
To insure operators are adequately selected, trained, rewarded, etc.
Establish time standards
Establish fair and equitable standards for work performance.
Follow up the method
Take measurements to determine if changes really did improve situation as predicted.

9. Example: Mission Planning and control for the Mars Exploration Rover
Researchers introduced automated planning tool, MAPGEN
Tool had to fit with users’ existing way of thinking about plans,
Introduction of new tools caused the planning process to change,
Product and processes were evolved together, over time.

10. Many methods can be used in many stages of the design process
A typical spiral design process
Prototype
Testing
Requirements
Gathering
Final Performance
Evaluation or
Comparison
Design
Specification
Design
Review

11. Problem Solving Tools for Methods Engineering: help to identify what the most important problem is
Observational tools:
Site walk-thrus
Observation and interviews of workers and managers
Ethnographic studies

12. Problem Solving Tools for Methods Engineering (Ch. 2.1)
Exploratory tools
Pareto Analysis (Vilfredo Pareto)
Fish Diagrams (from Japan, 60’s)
Gantt and PERT charts (40’s wartime).

13. Pareto Analysis
Items of interest are identified (e.g. types of product flaws that result in scrapped parts, time spent on each activity required to manufacture a product or perform a service.
Items are measured on a common scale (such as frequency total cost, total time, etc.)
Items are ordered in descending order

14. Example of a Pareto Chart

15. Example 2 Pareto chart: worker time study

16. Example of a Fish Diagram
                      
                 
Example of a Fish Diagram

17. Fish Diagrams Cause and effect diagrams
Effect is a problem = “fish head”
Causes = “fish bones”
Typical causes:
Environment
Methods
Materials
Administrative
Machine
Human

18. Gantt Charts Activities shown as bars with:
Anticipated start times
Anticipated completion times
Actual start and completion times
Use a vertical line to show current time
May use color codes to show various things:
Completed activities (grey)
On going activities, on schedule (green)
Overdue activities (red)
Almost over due activities (yellow)

19. Example of a GANTT chart

20. PERT Charts: Program Review and Evaluation Technique
Project networks
Like Gannt charts, PERT charts show activities, start and end times
Also show variation in activity durations: optimistic, average, pessimistic,
Show dependencies between activities,
Can identify a critical path (longest path) that constrains minimum completion time of whole project,
Analyze how “crashing” activities can shorten duration of whole project.

22.                       
                     
Example of a PERT chart

23. Problem Solving Tools (cont.)
Recording and Analysis tools:
Operation Process Chart
Flow process chart
Flow diagram
Worker and Machine Process Charts
Gang Process charts
Synchronous servicing

24. Operation Process Charts
Chronological sequence of operations
Show operations as a flow chart though the worksite.
Show the types of operations:
Operation
Transport
Inspection
Delay
Storage
Decision

25. Operation Process Chart: Manufacture of a telephone stand

26. Flow Process Chart More detail than Operation Process Chart:
Not usually used for entire assemblies,
Used for just one component (or operator)
Add in information on:
Operation duration (time to complete)
Distance traveled (for transport operations)
Good for showing savings of a new method.

27. Flow Process Chart Preparation of direct mail advertizing

28. Flow Diagram Show layout of work area
Show the flow of work through that area
Show congestion areas, crossing worker paths, total travel.
Identify how layout can be redesigned to reduce travel, motion, collisions, etc.
Store materials near where they are used.
Increase efficiency and safety.

29. Flow diagram

30. A revised and more efficient flow diagram

31. Worker and Machine Process Chart
Show one worker, many processes
Identify idle time for each,
Reorganize operations to reduce idle time.
Identify how many machines worker can manage

33. Gang Process Charts Show one machine, many workers,
Identify idle time for each,
Re-arrange tasks between workers to reduce idle time.

36. Synchronous and Random Servicing
Synchronous servicing: operations (usually done by machine) take a predictable amount of time, so the operator(s) “servicing” actions can be synchronized with the machines’ cycle times.
Random servicing (Asynchronous): operation occurrences happen with some unpredictability: e.g. machine breakages, field service calls, etc.

37. Synchronous Servicing
n ≤ l + m
l + w
The number of
Machines an operator
Can be assigned:
Where:
n = number of machines operator handles
l = total operator loading and unloading time
m = total machine running time
w = worker time between machines.

38. Example
Should n be 3 or 4?
Figure out how much it costs per unit of production if:
3 machines are assigned to each worker
4 machines are assigned to each worker
Choose the assignment that is least expensive.

39. Random Servicing
This method applies when you have one person handling several machines (or things) that:
Do not run for a set length of time,
Need servicing at irregular intervals
Examples:
Machine repair: machines break at random times.
Call center, calls come in at random times.

40. Random Servicing: Approach
The proportion of time, p, that a machine is up or down can be estimated through a time study (Chapter 9) or a work sampling study (Chapter 14)
q = 1 - p
P = the probability that m out of n total machines are down is:
P (m of n) = n! x pm qn-m
m! (n – m)!

41. Random Servicing: Example
Suppose at a call service center you have one phone operator to answer:
n = 4 phone lines
p = 0.10 = probability that a phone line is in use is.
q = 1 – p = 0.9 = the probability that a given phone line is unused, e.g. no one on the line.
“In use” means that a caller may be either:
waiting on the line, or
speaking with the phone operator.
If calls come into the center at random, what is the probability that there will be exactly three phone lines in use? (e.g. One caller speaking with the operator, two callers waiting).

42. Random Servicing: Example
No callers ! x (.10 ) (.94) = .66
0! (4 – 0)!
One caller ! x (.11 ) (.93 ) = .29
1! (4 – 1)!
Two callers 4! x (.12 ) (.92) = .05
2! (4 – 2)!
Three callers 4! x (.13 ) (.91) = .0036
3! (4 – 3)!
Four callers 4! x (.14 ) (.90) = .0001
4! (4 – 4)!

43. Random Servicing: Example
In other words, in this situation:
66 % of the time, the sales assistant has no calls;
29 % of the time, exactly one call;
5 % of the time, exactly two calls, e.g. the assistant helps one customer while one customer waits, 
Less than a half a percent of the time (0.36 %), exactly three calls: one customer is being helped while two customers listen to Musak. 
The probability that all 4 lines are in use at once is almost non-existent.

44. Coffee Shop Study
No studies had been done previously at this company to assess current efficiency
Goal: to identify any way possible of improving productivity,
Initial request: do a time study at 3 very different stores, improve productivity of coffee making process.
Corporate goal: customer should be in and out within 3 minutes, “door-to-door”.

45. Observational tools
Site walk-thrus: look at layout, tools equipment, how they are used.
Interviews of workers and managers to identify what they view as problems,
Ethnographic studies: observe work in detail as a “fly on the wall” as it normally occurs in its normal setting, possibly over a long period of time. Good for observing interactions between workers.
Time and/or motion studies: to learn detail about what people do and how long it takes.

46. Job Worksite Analysis Guide
Check list of items to think about/examine while touring jobsite:
How do parts/products flow in and out?
What kinds of motion are involved?
Are any tools being used?
Were there awkward motions?
Is worker fatigued? Stressed?
Is there decision making?

47. Time and Motion studies
In a time study:
Often applied to large or small tasks,
Work is observed Work is broken into “elements”
Each element is timed,
The process is re-engineered to be faster, safer, less error-prone, etc.
In a motion study:
Often applied to fine-grained continuous motions,
Motions are observed in performing a task, Motions are be divided into “therbligs”
The process is re-engineered by:
eliminating unnecessary motions,
re-sequencing motions.
The two are often combined.

48. Tools for Time and Motion Studies
Tools can be simple and low cost:
Stop watch,
Pen and paper,
Maybe a video camera. The task determines if it is necessary.
The technique is low-tech, but can still result in major cost savings!

49. How did your group speed up your assembly process?
Use multiple packers,
Use two hands,
Lay-out pieces in advance in order of assembly,
Orient each object in correct position in advance,
Sequence objects to be easier to pack,
Fewer objects = less material handing = time savings!

50. What about thinking tasks?
Time and motion studies apply to physical aspects of the task and physical objects.
What about the psychological aspects of a task? How can one study “thought work” and apply factors to improve the work of people who do: driving, design, planning, management, and decision making?

51. Additional Approaches: Time and “thought” studies
Protocol Studies
Have the person talk out loud as they solve a problem
E.g. create a design or manufacturing plan, or solve an algebraic problem
Record everything said and done on audio and video tape, or written notes
Ethnographic Studies
Observe in the workplace where people are doing tasks
Nuclear power plant
Cockpit of airplane
NASA control center (for Mars Explorations)
Record what is said and done (video or written notes)
Analyze

52. Example of a Protocol Study
Protocol means “record”
Need 2 volunteers
Experimenter
Subject
Tools:
Normal tools used for task, often pencil and paper in an office setting,
Experimenter needs pencil and paper (or other recording equipment: tape recorder, video).

53. A thinking task

54. Common themes in Human Factors approaches
Observation of human activities in performance of tasks,
Re-engineer many aspects of the task (tools, process, etc.) to improve effectiveness:
The tools and techniques are often simple but powerful!

55. In-Class Exercise
Each group will be given a set of objects to assemble into a box.
The items will be varied in:
shape
size,
flexibility,

56. In-Class Exercise Figure out how to fit all the objects in the box
Decide what actions constitute “therbligs” or “elements”
Develop and record a procedure (in terms of therbligs)
Figure out how to do it fast
Time your procedure (minutes, seconds)
Did your “therblig” descriptions change?
Did your procedure descriptions change?
Did other things change?

57. Rules of Exercise
Take all objects out and set them separately on desk.
Fit all objects in the box so that you can close the lid all the way.
No squashing or damaging objects.
You may wish to assign different roles to the people on your team: packer, time keeper, process recorder, observer, etc.
You will get several minutes to practice, then we will have a competition.

58. Exercise (continued) Each group please report:
Your best time to complete the task
Your therbligs
Your procedure (sequence of therbligs)
What you did to improve your time? (did you develop new therbligs? New sequence? Other?)

59. What Observational tools were used in Coffee Shop Study?
Interviews with employees
Site walk-thru
Time studies of operations for three types of store setups and three job roles (4 hours observation each):
Cashier
Superglue
Barista
Other measurements (had to design measurement methods appropriate for context):
At what rate do customers enter?
How long does it take an individual customer to go door to pick-up?

60. Site walk-thru: Customer Area

61. Tightly constrained workspace: Hard to find a safe place from which to observe!

63. Projects

64. Which Exploratory Tools did we Use in the Coffee Shop Study?
Other types of charts: rate of customer arrival: when are the busy times?
Comparison of total customer wait times at different stores,
Comparison of customer volume at different stores,

66. Volume
high
high
medium

68. Difficult Part:
How do you translate this exploratory data into ideas of what to do?
What does this say about where the problems might lie?
How do I know if the what the data shows is good or bad? Is the most costly item a “problem” or a necessary part of the process?