Download Report


Motion Study
Figen EREN.
Analysis of the basic
hand, arm, and body
movements of workers
as they perform work
Figen EREN
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)
Figen EREN
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
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
Use (U) – manipulate/use a tool
Figen EREN
17 Therbligs (continued)
7. Pre-position (PP) – position object for next
8. Position (P) – position object in defined
9. Assemble (A) – join two parts
10. Disassemble (DA) – seperate multiple parts
that were previously joined
11. Search (Sh) – attempt to find an object using
eyes or hand
Figen EREN
17 Therbligs (continued)
12. Select (St) – choose among several objects
in a group (hand-eye coordination is
13. Plan (Pn) – decide on an action (a short
pause or hesitation in the motions)
14. Inspect (I) – determine quality of object using
the eyes
15. Unavoidable delay (UD) – waiting due to
factors beyond worker control
16. Avoidable delay (AD) – worker waiting
17. Rest (R) – resting to overcome fatigue
Figen EREN
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Figen EREN
Classification of Therbligs
Effective therbligs:
 Transport empty
 Grasp
 Transport loaded
 Release load
 Use
 Assemble
 Disassemble
Mental Basic Elements:
 Inspect
Delay Elements:
 Rest
Ineffective therbligs:
Physical Basic Motion Elements:
 Hold
 Pre-position
Physical and Mental Basic Motion
 Position
 Search
 Select
Mental Basic Elements:
 Plan
Delay elements:
 Unavoidable delay
 Avoidable delay
 Method study at the therblig level seeks to
eliminate or reduce ineffective therbligs.
Figen EREN
Time Study
Figen EREN.
all the ways in which
time is analyzed in
work situations
Figen EREN
Time is important, because;
 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
Figen EREN
When Are Time Standards Beneficial?
 Characteristics of industrial situations in which
time standards would be beneficial
 Low productivity
 Repeat orders
 Long production runs
 Repetitive work cycles
 Short cycle times
Figen EREN
Functions of Time Standards
 They define a “fair day’s work”
 They provide a means to convert workload into
staffing and equipment needs
 They allow alternative methods to be
compared objectively
 They provide a basis for wage incentives and
evaluation of worker performance
 They provide time data for:
 Production planning and scheduling
 Cost estimating
 Material requirements planning
Figen EREN
Average Worker
A worker who is representative of the persons
who usually perform tasks similar to the task
being measured
 If the work is performed mostly by men, then
the average worker is male
 If the work is performed mostly by women, then
the average worker is female
Figen EREN
Standard Performance
A pace of working that can be maintained by an
average worker throughout an entire work shift
without harmful effects on the worker’s health
or physical well-being
 The work shift includes periodic rest breaks
and occasional interruptions are experienced
by the worker
 Benchmarks of standard performance(EX:
 Walking at 3 miles/hr on level flat ground
 Dealing four hands of cards from a 52 card
deck in exactly 30 sec)
Figen EREN
Distribution of Worker Performance
Worker performance is expressed in terms of
daily output
Figen EREN
How a Standard Time is Defined
Distribution of worker performance, indicating
how standard time is defined so that it can be
readily achieved by most workers
Figen EREN
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
 Standard time:
Tstd = Tn(1 + Apfd)
where pfd = Personal time, Fatigue, and Delays
Figen EREN
Rest Periods
 Common in industry
 Paid for by the employer as regular work
 Rest breaks usually included in allowance
factor built into the time standard
 Relatively short duration - 5 to 20 minutes
 Meal periods - not included
Figen EREN
Figen EREN.
Ergonomics can be defined as
the application of knowledge of
human characteristics to the
design of systems
Figen EREN
Human Variability
 Differences in body dimensions exist among
people because of:
 Ethnicity and Nationality
 Heredity
 Diet
 Health
 Sex
 Age
 Living conditions
Figen EREN
Static Dimensions of Human Body
Figen EREN
Anthropometric Design Principles
Design for extreme individuals
Design for adjustability
Design for the average user
Design different sizes for different size users
Figen EREN
Design for Extreme Individuals
 Designing for the maximum
 Doorway heights
 Automobile door openings
 Mattress sizes
 Designing for the minimum
 Heights of kitchen cabinets
 Locations of levers and dials on equipment
 Weights of portable power tools
Figen EREN
Design for Adjustability
 To accommodate a wide range of users
 Examples:
 Automobile driver seats
 Adjustable steering wheel in an automobile
 Office chairs
 Worktable heights
 Tilt angles of computer monitors
 Lawnmower handle heights
 Bicycle handlebars
Figen EREN
Adjustable Chair for Workplace
Figen EREN
Design for Average User
 For situations in which design for extreme
individuals and adjustability are not feasible
 Examples:
 Stair heights
 Stadium seats
 Sofas
 Heights of checkout counters at
 Lengths of shovel handles
Figen EREN
Workplace Arrangement
 Normal and maximum working areas in the
Design for
Work Systems and the Methods, Measurement, and Management of Work
Figen EREN
Different Sizes for Different Size Users
 When the only way to accommodate user
population is to make the product in different
 Examples:
 Clothing
 Shoes
 Elementary school desks and chairs
Figen EREN
The Physical Work
1.The Visual Environment and
2.The Auditory Environment
and Noise
3.Climate Control in the Work
Figen EREN
Visual Environment and Lighting
 About 80% of the information input to the human
brain comes from visual stimuli
Relative possibility of being seen under prevailing
conditions of light, distance, and related factors
 Most important factor = level of illumination
 Other factors:
 Visual angle - angle subtended at the eye by the
smallest distinguishable detail
v = 3438 h/d
where v is measured in arc minutes
 Brightness contrast - relative luminance between
object and background
 Color
Figen EREN
Lighting Systems
 Lamp - a single artificial source of light (e.g., an
incandescent lamp, fluorescent lamp)
 Luminaire - complete lighting unit, including
 One or more lamps
 Reflectors and other apparatus to distribute
the light
 Means to connect to power supply
Figen EREN
Auditory Environment and Noise
 The second most important means by which
humans receive information
 Visual and auditory stimuli account for 95% or
more of a person's information input
 The auditory environment also includes:
 Noise - defined as unwanted sound
Figen EREN
Effects of Noise on Humans
 Distraction
 Negative emotions such as annoyance,
frustration, anger, and fear
 Interference with conversation, thinking, and
other cognitive processes
 Interference with sleeping
 Temporary hearing loss
 Permanent hearing loss
Figen EREN
Climate Control
Four primary variables that define climate:
1. Air temperature
2. Humidity - usually relative humidity
3. Air movement
4. Radiation from surrounding objects,
including the sun
Most comfortable working environment (called
the comfort zone)
 Air temperature = 19 to 26C (66 to 79F)
 Relative humidity = 50%
 Slow air movement = 0.2 m/s (0.64 ft/sec)
Figen EREN
Heat Stress
Occurs when body absorbs more heat than it
gives off, raising the body core temperature
Illnesses resulting from heat stress:
1. Heat rash - areas of skin erupt into red or
white bumps due to inflammation of sweat
2. Heat cramps - spasms of muscles in physical
3. Heat exhaustion - muscle weakness, nausea,
4. Heatstroke - fever, dry skin, convulsions,
coma (in extreme cases: death)
Figen EREN
Cold Stress
 Drop in core body temperature below normal
due to net heat loss from combination of low
temperature and air movement
 Windchill factor - estimates cooling effect of
moving air on exposed skin
 Jobs where cold stress is a problem:
 Refrigerated warehouses
 Construction jobs in wintertime
 Aboard ships in extreme northern climates
 Research in Antarctica
Figen EREN