Figen EREN. Motion Study

Figen EREN Definition 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 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

Figen EREN. 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

Figen EREN 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 Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. 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. 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. 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. Therbligs

Figen EREN. Example

Figen EREN. 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 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  Method study at the therblig level seeks to eliminate or reduce ineffective therbligs.

Figen EREN. Time Study

Figen EREN Definition 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 A pfd to obtain the standard time  Purpose of allowance factor is to compensate for lost time due to work interruptions and other reasons  Standard time: T std = T n (1 + A pfd ) where pfd = Personal time, Fatigue, and Delays

Figen EREN. 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

Figen EREN. ERGONOMY

Figen EREN Definition 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 Standing Seated

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 supermarkets  Lengths of shovel handles

Work Systems and the Methods, Measurement, and Management of Work Figen EREN. Workplace Arrangement  Normal and maximum working areas in the workplace Design for average user

Figen EREN. 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

Figen EREN. The Physical Work Environment 1.The Visual Environment and Lighting 2.The Auditory Environment and Noise 3.Climate Control in the Work Environment

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 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)

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