figen eren. motion study. figen eren definition analysis of the basic hand, arm, and body movements...
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Figen EREN.
Motion Study
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Definition
Analysis of the basic hand, arm, and body movements of workers as they perform work
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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)
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17 Therbligs
1. Transport empty (TE) – reach for an object with empty hand – today we call it “reach”
2. Grasp (G) – grasp an object by contacting and closing the fingers until control has been achived
3. Transport loaded (TL) – move an object with hand and arm – today we call it “move”
4. Hold (H) – hold an object with one hand
5. Release load (RL) – release control of an object
6. Use (U) – manipulate/use a tool
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17 Therbligs (continued)
7. Pre-position (PP) – position object for next operation
8. Position (P) – position object in defined location
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
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17 Therbligs (continued)
12. Select (St) – choose among several objects in a group (hand-eye coordination is involved)
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
Work Systems and the Methods, Measurement, and Management of Workby Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Therbligs
Work Systems and the Methods, Measurement, and Management of Workby Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Therbligs
Work Systems and the Methods, Measurement, and Management of Workby Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Therbligs
Work Systems and the Methods, Measurement, and Management of Workby Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Therbligs
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Example
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Classification of Therbligs
Effective therbligs:Physical Basic Motion Elements: Transport empty Grasp Transport loaded Release load Use Assemble DisassembleMental Basic Elements: InspectDelay Elements: Rest
Ineffective therbligs:Physical Basic Motion Elements: Hold Pre-positionPhysical and Mental Basic Motion Elements: Position Search SelectMental Basic Elements: PlanDelay elements: Unavoidable delay Avoidable delay
Method study at the therblig level seeks to eliminate or reduce ineffective therbligs.
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Time Study
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Definition
all the ways in which time is analyzed in work situations
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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
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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
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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
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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
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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)
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Distribution of Worker Performance
Worker performance is expressed in terms of daily output
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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
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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
Standard time:
Tstd = Tn(1 + Apfd)
where pfd = Personal time, Fatigue, and Delays
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Rest Periods
Common in industry
Paid for by the employer as regular work time
Rest breaks usually included in allowance factor built into the time standard
Relatively short duration - 5 to 20 minutes Meal periods - not included
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ERGONOMY
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Definition
Ergonomics can be defined as
the application of knowledge of
human characteristics to the
design of systems
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Human Variability
Differences in body dimensions exist among people because of: Ethnicity and Nationality Heredity Diet Health Sex Age Living conditions
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Static Dimensions of Human Body
Standing
Seated
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Anthropometric Design Principles
Design for extreme individuals Design for adjustability Design for the average user Design different sizes for different size users
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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
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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
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Adjustable Chair for Workplace
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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
supermarkets Lengths of shovel handles
Work Systems and the Methods, Measurement, and Management of WorkFigen EREN
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Workplace Arrangement
Normal and maximum working areas in the workplace
Design for average
user
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Different Sizes for Different Size Users
When the only way to accommodate user population is to make the product in different sizes
Examples:
Clothing
Shoes
Elementary school desks and chairs
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The Physical Work Environment
1.The Visual Environment and Lighting
2.The Auditory Environment and Noise
3.Climate Control in the Work Environment
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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
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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
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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
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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
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Climate Control
Four primary variables that define climate:1. Air temperature2. Humidity - usually relative humidity3. Air movement4. Radiation from surrounding objects,
including the sun Most comfortable working environment (called
the comfort zone) Air temperature = 19 to 26C (66 to 79F) Relative humidity = 50% Slow air movement = 0.2 m/s (0.64 ft/sec)
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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 glands
2. Heat cramps - spasms of muscles in physical labor
3. Heat exhaustion - muscle weakness, nausea, dizziness
4. Heatstroke - fever, dry skin, convulsions, coma (in extreme cases: death)
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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