1. IE 101-Industrial Engineering Orientation
Fall 2009
Motion and Time Study
Engin Topan

2. Methodology Outline of MTS Develop System Methods Design
Design work methods (sequence of operations and procedures) that make up the preferred solution
Find better methods for work
Standardize
Form written standards for operations
Time Standards
Determine a standard time for each operation
Training
Train the operators
Methods
Design
Develop System
Standardize
Work
Meas.mnt
Time Standards
Training

3. Defining Work Systems Work Is our primary means of livelihood
Serves an important economic function in the global world of commerce
Creates opportunities for social interactions and friendships
Provides the products and services that sustain and improve our standard of living

4. Defining Work Systems Work consists of tasks
Tasks consist of work elements
Work elements consist of basic motion elements

5. Defining Work Systems Task
An amount of work that is assigned to a worker or for which a worker is responsible
Repetitive task – as in mass production
Non-repetitive task – performed periodically, infrequently, or only once
Work Element
A series of work activities that are logically grouped together because they have a unified function in the task
Example: assembling a component to a base part using several nuts and bolts

6. Defining Work Systems Basic Motion Elements
Actuations of the limbs and other body parts
Examples:
Reaching for an object
Grasping the object
Moving the object
Walking
Eye movement
A work element consists of multiple basic motion elements

7. 1.3 Defining Work Systems “Time=Money”? How?
New product introduction
Product cost
Delivery time
Overnight delivery
Competitive bidding
Production scheduling
Increase profit using less time!

8. Defining Work Systems Importance of Time in Work
Time is the most frequently used measure of work
How many minutes or hours are required to perform a given task?
Most workers are paid by the time they work
Hourly wage rate
Salary
Workers must arrive at work on time
Labor and staffing requirements computed in units of time

9. Defining Work Systems
A work system is a system consisting of humans, information, and equipment designed to perform useful work
Contributes to the production of a product or delivery of a service
Examples:
Worker operating a machine tool in a factory
Robotic welding line in an automobile plant
A receptionist answering incoming phone calls

10. Defining Work Systems

11. Productivity Production as a function in Economics Q=f(K,L)
Q: Output, K: Capital, L: Labor
Is there a way to change function f with a better function g?
Better Function=Higher Productivity

12. Productivity Productivity
The level of output of a given process relative to the level of input
Process can refer to
Individual production or service operations
A national economy
Productivity is an important metric in work systems because
Improving productivity is the means by which worker compensation can be increased without increasing the costs of products and services they produce

13. Productivity Labor Productivity
The most common productivity measure is labor productivity, defined by the following ratio:
LPR =
LPR = labor productivity ratio
WU = work units of output
LH = labor hours of input

14. Productivity
Labor Productivity Index
Measure that compares input/output ratio from one year to the next
LPI =
LPI = labor productivity index
LPRt = labor productivity ratio for period t
LPRb = labor productivity ratio for base period

15. Productivity
Example
During the base year in a small steel mill, 326,000 tons of steel were produced using 203,000 labor hours. In the next year, the output was 341,000 tons using 246,000 labor hours.
Determine: (a) the labor productivity ratio for the base year, (b) the labor productivity ratio for the second year, and (c) the productivity index for the second year.

16. Productivity Solution (a) In the base year, LPR = 326,000 / 203,000
= tons per labor hour
(b) In the second year, LPR = 341,000 / 246,000
= tons per labor hour
(c) Productivity index for the second year
LPI = / = 0.863
Comment: No matter how it’s measured, productivity went down in the second year.

17. Productivity Labor Factor in Productivity
Labor itself does not contribute much to improving productivity
More important factors:
Capital - substitution of machines for human labor
Technology - fundamental change in the way some activity or function is accomplished

18. Productivity Horse-drawn carts Railroad trains Steam locomotive
Telephone operator
Manually operated milling machine
Railroad trains
Diesel locomotive
Dial phone
Numerically controlled (NC) milling machine

19. Productivity Measuring Productivity
Not as easy as it seems because of the following problems:
Nonhomogeneous output units
Multiple input factors
Labor, capital, technology, materials, energy
Price and cost changes due to economic forces
Product mix changes
Relative proportions of products that a company sells change over time

20. Productivity Productive Work Content
A given task performed by a worker can be considered to consist of
Basic productive work content
Theoretical minimum amount of work required to accomplish the task
Excess nonproductive activities
Extra physical and mental actions of worker
Do not add value to the task
Do not facilitate the productive work content
Take time

21. Productivity
Excess Nonproductive Activities can be classified into three categories:
Excess activities due to poor design of product or service
Excess activities caused by inefficient methods, poor workplace layout, and interruptions
Excessive activities cause by the human factor

22. Allocation of Total Task Time
Productivity
Allocation of Total Task Time

23. Work Systems Manual work system Worker-machine system
Worker performing one or more tasks without the aid of powered tools
Worker-machine system
Human worker operates powered equipment
Automated work system
Process performed without the direct participation of a human worker

24. Work Systems Manual Work Systems
Human body accomplishing some physical task without an external source of power
With or without hand tools
When hand tools are used, the power to operate them is derived from the strength and stamina of a human worker
Other human faculties are required, such as hand-eye coordination and mental effort

25. Work Systems
Manual Work Systems

26. Work Systems Pure Manual Work
Material handler moving cartons in a warehouse
Assembly worker snap-fitting two parts together
Manual Work with Hand Tools
Material handling worker using a dolly to move furniture
Assembly worker using screwdriver

27. Work Systems Worker-Machine Systems
Worker operating a piece of powered equipment
Examples:
Machinist operating a milling machine
Construction worker operating a backhoe
Truck driver driving an 18-wheeler
Worker crew operating a rolling mill
Clerical worker entering data into a PC

28. Worker-Machine Systems
Work Systems
Worker-Machine Systems

29. Work Systems Automated Work Systems
Automation is the technology by which a process or procedure is accomplished without human assistance
Implemented using a program of instructions combined with a control system that executes the instructions
Power is required to drive the process and operate the control system

30. Work Systems
Automated Work System

31. Methods
Design
Develop System
Standardize
Time Standards
Training
Methods Design
Motion study - 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
Includes:
Workplace layout and environment
Tooling and equipment used in the task

32. Motion Study Basic Motion Elements
Therbligs – 17 basic motion elements
Basic building blocks of virtually all manual work performed at a single location
With modification, used today in several work measurement systems, e.g., MTM and MOST
Some of the motion element names and definitions have been revised

33. Motion Study 17 Therbligs Transport empty (TE) – reach for an object
Grasp (G) – grasp an object
Transport loaded (TL) – move an object with hand and arm
Hold (H) – hold an object
Release load (RL) – release control of an object
Use (U) – manipulate a tool

34. Motion Study Pre-position (PP) – position object for next operation
Position (P) – position object in defined location
Assemble (A) – join two parts
Disassemble (DA) – separate multiple parts that were previously joined
Search (Sh) – attempt to find an object using eyes or hand

35. Motion Study Select (St) – choose among several objects in a group
Plan (Pn) – decide on an action
Inspect (I) – determine quality of object
Unavoidable delay (UD) – waiting due to factors beyond worker control
Avoidable delay (AD) – worker waiting
Rest (R) – resting to overcome fatigue

36. Classification of Therbligs
Motion Study
Classification of Therbligs
Effective therbligs:
Transport empty
Grasp
Transport loaded
Release load
Use
Assemble
Disassemble
Inspect
Rest
Ineffective therbligs:
Hold
Pre-position
Position
Search
Select
Plan
Unavoidable delay
Avoidable delay

37. Motion Study Micromotion Analysis 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

38. Example: A repetitive Manual Task
Current method: An assembly worker performs a repetitive task consisting of inserting 8 pegs into 8 holes in a board. A sightly interference fit is involved in each insertion. The worker holds the board in one hand and picks up the pegs from a tray with other hand and inserts them into the holes, one peg at a time.

39. Example: A repetitive Manual Task
Current method and current layout:

40. Example A repetitive Manual Task
Improved method and improved layout:
Use a work-holding device to hold and position the board while the worker uses both hands simultaneously to insert pegs.
Instead of picking one peg at a time, each hand will grab four pegs to minimize the number of times the worker’s hands must reach the trays.

41. Motion Study 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

42. Work Methods Design To select preferred work method:
Eliminate all unnecessary work
Combine operations or elements
Change the sequence of operations
Simplify the necessary operations

43. Time Study and Work Measurement
Meas.mnt
Develop System
Standardize
Time Standards
Training
Time Study and Work Measurement
Time Is Important
Most workers are paid for their time on the job
The labor content (cost of labor time) is often a major factor in the total cost of a product or service
For any organization, it is important to know how much time will be required to accomplish a given amount of work

44. Time Study and Work Measurement
Work measurement – evaluation of a task in terms of the time that should be allowed by an average worker to perform the task
Time study – all the ways in which time is analyzed in work situations
Standard time – amount of time that should be allowed for an average worker to process one work unit using the standard method and working at normal pace

45. Time Study and Work Measurement
Standard times
define a “fair day’s work”
provide a means to convert workload into staffing and equipment needs
provide a basis for wage incentives and evaluation of worker performance
provide time data for:
Production planning and scheduling
Cost estimating
Material requirements planning

46. Task Hierarchy & Work Measurement
Time Study and Work Measurement
Task Hierarchy & Work Measurement

47. Time Study and Work Measurement
Prerequisites for Valid Time Standards: Factors that must be standardized before a time standard can be set

48. Time Study and Work Measurement
Normal Performance
A pace of working that can be maintained by a properly trained average worker throughout an entire work shift without deleterious short-term or long-term effects on the worker’s health or physical well-being
Normal performance = 100% performance
Common benchmark of normal performance:
Walking at 3 mi/hr

49. Time Study and Work Measurement
Performance Rating
Analyst judges the performance or pace of the worker relative to the definition of standard performance used by the organization
Standard performance Pw = 100%
Slower pace than standard Pw < 100%
Faster pace than standard Pw > 100%
Normal time Tn = Tobs(Pw )

50. Time Study and Work Measurement
Normal Time
The time to complete a task when working at normal performance
Tn = Tobs(Pw )
where Tobs = observed time, Tn = normal time, and Pw = worker performance or pace

51. Time Study and Work Measurement
Example: Normal Performance
Given: A man walks in the early morning for health and fitness. His usual route is 1.85 miles. A typical time is 30 min. The benchmark of normal performance = 3 mi/hr.
Determine: (a) how long the route would take at normal performance and (b) the man’s performance when he completes the route in 30 min.

52. Time Study and Work Measurement
(a) At 3 mi/hr, time = 1.85 mi / 3 mi/hr
= hr = 37 min
(b) Rearranging equation, Pw = Tn / Tc
Pw = 37 min / 30 min = = %

53. Reasons for Lost Time at Work
Time Study and Work Measurement
Reasons for Lost Time at Work
Work-related interruptions
Machine breakdowns
Waiting for materials or parts
Receiving instructions from foreman
Talking to co-workers about work-related matters
Rest breaks for fatigue
Cleaning up at end of shift
Non-work-related interruptions
Personal needs (e.g., restroom breaks)
Talking to co-workers about matters unrelated to work
Lunch break
Smoke break
Beverage break
Personal telephone call

54. Time Study and Work Measurement
How to Allow for Lost Time
Two approaches used by companies:
Scheduled rest breaks during the shift
Typical - one 15-minute break in mid-morning and another in mid-afternoon
A PFD allowance is added to the normal time
This allows the worker to take a break on his/her own time

55. Time Study and Work Measurement
PFD Allowance
Personal time
Rest room breaks, phone calls, water fountain stops, cigarette breaks (5% typical)
Fatigue
Rest allowance to overcome fatigue due to work-related stresses and conditions (5% or more)
Delays
Machine breakdowns, foreman instructions (5% typical)

56. Time Study and Work Measurement
Allowances in Time Standards
Normal time is adjusted by an allowance factor Apfd to obtain the standard time
Purpose of allowance factor is to compensate for lost time due to work interruptions and other reasons

57. Time Study and Work Measurement
Standard Time
Defined as the normal time but with an allowance added in to account for losses due to personal time, fatigue, and delays
Tstd = Tn (1 + Apfd)
where Tstd = standard time, Tn = normal time, and Apfd = PFD allowance factor
where pfd = personal time, fatigue, and delays
Also called the allowed time

58. Time Study and Work Measurement
Standard Performance
Same as normal performance, but acknowledges that periodic rest breaks must be taken by the worker
Periodic rest breaks are allowed during the work shift
Other interruptions and delays also occur during the shift

59. Time Study and Work Measurement
Standard Method
Must include all of the details on how the task is performed, including:
Procedure - hand and body motions
Tools
Equipment
Workplace layout
Irregular work
Working conditions
Setup

60. Time Study and Work MeasurementTc
cycle
time Tn
normal
time
Tstd
standard
time
Pw rating
Apfd allowances

61. Time Study and Work Measurement
Irregular Work Elements
Elements that are performed with a frequency of less than once per cycle
Examples:
Changing a tool
Exchanging tote pans of parts
Irregular elements are prorated into the regular cycle according to their frequency

62. Time Study and Work Measurement
Example: Determining Standard Time
Given: The normal time to perform the regular work cycle is 3.23 min. In addition, an irregular work element with a normal time = 1.25 min is performed every 5 cycles. The PFD allowance factor is 15%.
Determine (a) the standard time and (b) the number of work units produced during an 8-hr shift if the worker's pace is consistent with standard performance.

63. Time Study and Work Measurement
Normal time Tn = /5
= 3.48 min
Standard time Tstd = 3.48 ( )
= 4.00 min
(b) Number of work units produced during an 8-hr shift
Qstd = 8.0(60)/4.00 = 120 work units

64. Direct Time Study
Direct and continuous observation of a task using a stopwatch or other timekeeping device to record the time taken to accomplish the task
While observing and recording the time, an appraisal of the worker’s performance level is made to obtain the normal time for the task
The data are then used to compute a standard time for the task

65. Direct Time Study Direct Time Study Procedure
Define and document the standard method
Divide the task into work elements
Time the work elements to obtain the observed time Tobs
Evaluate worker’s pace relative to standard performance to obtain normal time Tn
Called performance rating (PR)
Tn = Tobs(PR)
Apply allowance factor to compute standard time
Tstd = Tn(1 + Apfd)

66. Direct Time Study Document the Standard Method
Determine the “one best method”
Seek worker’s advice if possible
Documentation should include:
All of the steps in the method
Special tools, gauges, equipment and equipment settings (e.g., feeds and speeds) if applicable
Irregular elements and their frequency
Once the standard method is defined, it should not be possible for the operator to make further improvements

67. Direct Time Study
Direct time study form

68. Direct Time Study Example
A direct time study was taken on a manual work element using the snapback method. The regular cycle consisted of three elements, a, b, and c. Element d is an irregular element performed every five cycles.
Work element a b c d
Observed time (min)
Performance rating % % % %
Determine (a) normal time and (b) standard time for the cycle

69. Direct Time Study (a) Normal time:
Tn = 0.56(1.00) (0.80) (1.0)
+ 1.10(1.0)/5 = 1.53 min
(b) Standard time:
Tstd = 1.53( ) = 1.76 min

70. Work Sampling
Statistical technique for determining the proportions of time spent by subjects in various defined categories of activity
Subjects = workers, machines
Categories of activity = setting up a machine, producing parts, idle, etc.
For statistical accuracy
Observations must be taken at random times
Period of the study must be representative of the types of activities performed by the subjects

71. Work Sampling When is Work Sampling Appropriate?
Sufficient time is available to perform the study
Several weeks usually required for a work sampling study
Multiple subjects
Work sampling suited to studies involving more than one subject
Long cycle times for the jobs covered by the study
Nonrepetitive work cycles
Jobs consist of various tasks rather than a single repetitive task

72. Work Sampling Example: How Work Sampling Works
A total of 500 observations taken at random times during a one-week period (40 hours) on 10 machines with results shown below.
Category No. of observations
(1) Being set up
(2) Running production 300
(3) Machine idle 125
500
How many hours per week did an average machine sped in each category?

73. Work Sampling
Proportions of time determined as number of observations in each category divided by 500
Time in each category determined by multiplying proportion by total hours (40 hr)
Category Proportion Hrs per category
(1) Being set up /500 = x 40 = 6
(2) Running production 300/500 = x 40 = 24
(3) Machine idle 125/500 = x 40 = 10

74. Work Sampling Work Sampling Applications
Machine utilization - how much time is spent by machines in various categories of activity
Previous example
Worker utilization - how workers spend their time
Allowances for time standards - assessment of delay components in PFD allowance factor
Average unit time - determining the average time on each work unit
Time standards - limited statistical accuracy when standards set by work sampling

75. Work Sampling Observation Form

76. References
Groover, Mikell P., Work Systems: The Methods, Measurement & Management of Work, 2007, Prentice Hall
Barnes, Ralph M., Motion and Time Study: Design and Measurement of Work, 1990, John Wiley & Sons Inc.