Time Study=Work MeasurementPart 1

Prof.Dr.Yasemin Claire ERENSAL

Are based on the data collected throughwork measurement processes.

Work Standards

They should not be set at such a level thatonly the most productive worker will beable to attain them.Nor should they be set at such a level thatnearly every employee can attain them withputting forth little effort to do so.

1. They help increase the efficiency with which employees perform their jobs.2. They help inform employees of their expected production levels.

3. They assist managers in making personnel decisions, because employees who are performing beyond expected levels of production can be readily identified.

Advantages of Work Standards(1 of 2)

4. Because employees are aware of the procedures for performing their jobs, less supervision is needed and greater control over the work process is possible.

5. They provide the basis for incentive wage systems.6. They help improve employee morale by making employees aware of what is expected of them.

Advantages of Work Standards(2 of 2)

QuantityStandards

QualityStandards

DescriptiveStandards

Are expressed in units ofoutput per unit of time.

Measure the accuracy andacceptability of work.

Identify what is acceptable in terms of the descriptive nature of something in anoffice, such as furniture.

Types of Standards

Work Measurement

• Work measurement refers to the process of estimating the amount of worker time required to produce one unit of output.

• Work measurement is a process of analyzing jobs for the purpose of setting time standards.

• The goal of work measurement is to develop labor standards that can be used for planning and controlling operations.

1. To express expected output or production levels.2. To aid in the planning and scheduling of work.3. To aid in determining the number of employees needed to complete a project in the allotted time.4. To aid in determining the efficiency of work methods and procedures.

Objectives of Work Measurement (1/2)

5. To aid in determining the cost of office operations.

6. To aid in determining equitable work loads for employees.

Objectives of Work Measurement (2/2)

Labor Standards

• A labor standard can be determined using one or more of the following approaches:----------- subjective ------------

– Historical standards

– Supervisor estimates

----------- objective ------------

– Standard Data

– Work sampling

– Time study

– Predetermined time standards

Production Records and Expert Opinion Time Standards and Historical Data

(Subjective)• Estimation of time required to do a specific time,

normally performed by a supervisor – expert opinion• Unfair due to variability among estimators

– Looking at a job and judging the amount of the time needed

• Historical data – records of previous times used on each job– does not include what time it should have taken– Relatively easy, convenient, and inexpensive– Not objective, unknown accuracy– Not recommended

Production Records and Expert Opinion Time Standards and Historical Data

(Subjective)1. It is simple, easily understood, and

inexpensive.2. It facilitates the quick development and

implementation of a work measurement program without the need for specially trained individuals.

Disadvantages of Production Records and Expert Opinion Time Standards and

Historical Data (Subjective)1. It may produce inaccurate standards if

employees don’t prepare accurate time logs. 2. It results in preparation of standards on the

basis of “what is” rather than on the basis of “what should be.”

Standard Data

• Fastest & cheapest technique – may be more accurate & consistent than any other time study technique.

• Compare previously set time standards to varying times on specific machines or class of machines.

• Communicate time standards through graphs, tables, worksheets, and formulas. Reference text (i.e. Machinery Handbook) or equipment manufacturers are a good source of standard data.

Work Sampling Technique (1/2)

• Uses a statistical base that requires random observations to determine the amount of time taken by each element of an office procedure.

Statistical element is based on this law of probability: If a procedure is observed a sufficient number of times, the results will be as reliable as when the procedure is observed continuously over a period of time.

Work Sampling Technique (2/2)

• The process helps determine what percent each activity consumes in a whole work process.

• Observe people working & draw conclusions• This subject will furtherly handled on the

next weeks.

Time Study

• Establishes a standard for a given task

• Measures work content, allows for fatigue, personal and unavoidable delays

• Increases the efficiency of the equipment and personnel

1. Results in the development of accurate standards.2. Produces more accurate results when measuring work processes comprised of minute elements than either the production records technique or the work sampling technique.3. Results in the development of standards that can be readily used for assessing the performance of employees.

Advantages of the Time Study Technique

1. The measurement process often requires the use of a trained analyst.2. Office employees tend to have a negative reaction to standards determined by the use of a stopwatch.3. The technique is not useful for measuring time- consuming elements of a work process.

Disadvantages of Time Study Technique

Uses data typically obtained from external sources, such as purchased data.

Tends to produce highly uniform results when based on standards that are consistent from one situation to another.

Predetermined Standard Time Data Technique (1 of 2)

Visualize needed tools, equipment, & work methods– work divided into 17 work elements (therbligs)

1. The work process is broken down into its minute elements.2. Each element is analyzed in terms of the motion involved.3. To determine the appropriate standard, each motion of the work process is compared with the purchased predetermined standard time data.4. The standard for the entire process is found by adding the standard times for each of the motions.

Predetermined Standard Time Data Technique (2 of 2)

Steps

1. It results in accurate standards.

2. Employees tend to accept results readily because of the specificity of the process.3. Application of process is fairly rapid.

Advantages of Predetermined Standard Time Data Technique

1. It is a costly technique.

2. It is not suitable for certain types of office operations.

Disadvantages of Predetermined Standard Time Data Technique

•Is a process that results in the adjustment of employee work standards, helping determine what constitutes a fair day’s work for both the employer and employee.•The amount of work that can be produced by a qualified employee when working at a normal pace and effectively utilizing their time where work is not restricted by process limitations

Performance Leveling

Responsibilities in Work Measurement Activities

Analysts Responsibility

• Normalize time• Correct method, and understanding by all those

involved in the study• Accuracy and good judgment essential• Good human relations most important: show respect• Answer questions to allieviate fears: TS must never

become vindictive: Sally Fields• Sign the study

Supervisor's Responsibility

• Notify operator in advance

• Verify correct tools, equipment, supplies, and method.

• Select a qualified, cooperative operator and answer all questions in advance of the study.

• Sign the study

Union’s Responsibility

• Most are opposed. They must recognize the necessity for profitability.

• Provide members training in TS to promote acceptance and validity.

• Make sure study includes a complete record of the job.

• May wish to be present at the time of the study.

Operator’s Responsibility

• Assist in the establishment of the most efficient method for the job.

• Assist in breaking down job into elements that can be useful

• Cooperate during the study• Avoid vigorous application of non-essential

elements.• Sign the study• Do not sit during the time study

Work Measurement

• Standard time: (Labor standards)– The length of time a qualified worker, using appropriate

tools & procedures, will take to complete a job

• A labor standard is the number of worker-minutes required to complete an element, operation, or product under ordinary operating conditions.

• Ordinary operating conditions refers to a hypothetical average situation ….. average or typical worker, material, machinery, environment, etc.

Labor (Time) Standard

• Time required to produce a product at a work station with the following:– Qualified, well-trained operator– Working at a normal pace– Doing s specific task

• Before data are gathered, all wasted motions are eliminated from the process being analyzed.

• Time in decimal minutes (3 decimal places)• Pieces per hour • Hours per piece

Learning Curves

Workforce Productivity Improvement – Learning Curves

• A learning curve shows the reduction in time it takes to complete a task as the number of times it has been completed increases.

– Individuals, groups, and organizations all have learning curves

• The learning rate is the amount of improvement obtained as a task is repeated.

– The gain expressed by the learning rate is achieved every time the number of repetitions doubles.

– The learning rate is almost always a prediction. There are always errors in predictions, and errors in estimating the learning rate can have a tremendous impact on the projected time

Workforce Productivity Improvement – Learning Curves

• If an individual completed a task for the first time in 4 hours and his learning rate was expected to be 90%, we would observe the following pattern:

Exhibit 16.7 Learning Curve Pattern

Workforce Productivity Improvement – Learning Curves

• A lower percentage means faster learning. 85% vs. 97% learning curves:

Exhibit 16.8 85 percent learning curve Exhibit 16.9 97 percent learning curve

Workforce Productivity Improvement – Learning Curves

• The equation for the learning curve is

Tn = T1nr

WhereTn = time in hours to produce nth unitT1 = time in hours to produce the first unitn = number of the unit of interestr = log l/log 2 where l is the expected learning rate

Workforce Productivity Improvement – Learning Curves

• Example 16.3:

– A producer of machined components wants to determine the time it will take to produce the 300th unit on a new machine. The time for the first unit is 1.75 hours and the learning rate is 96%

• Tn = T1nr

• T300 = 1.75(300)log 0.96/log 2

= 1.75(300)-0.0589

= 1.75(300)0.0589

= 1.2506 hours

Training approaches

INSTALL NEW METHOD:Need to train workers in new method1) 'Learn-on-the-job' approach- learn wrong method- bother other operators, lower production- anxiety2) Simple written instructions - only good for very simple jobs3) Pictorial instructions - 'pictures worth 1000 words‘4) Videotapes - dynamic rather than static5) Physical training -- real equipment or simulators, valid- doesn't interrupt production- monitor performance- simulate emergencies

Factors that affect human learning

1) Job complexity - long cycle length, more training, amount of uncertainty in movements, more C-type motions, simultaneous motions

2) Individual capabilities- age, rate of learning declines in older age, amount of prior training, physical capabilities, active, good circulation of oxygen to brain

Learning Curves

• Assumption is that given exposure to repetitive tasks workers are likely to learn from cumulative experience how such tasks can be performed more quickly and efficiently, e.g. the second identical house can be constructed for less than the first; learning reduces the cost of succeeding units

• learning curves relate cost to cumulative nr.s of units produced

Learning Curve For Mass Production

• Processing time decreases with worker learning (experience)

• Time per unit decreases by constant percentage each time output doubles

• Use to plan labour, budget & scheduling requirements

Learning Curve Definition

The Learning Curve is a tool to help estimate future manufacturing costs. It is based on a relationship between cost (the dependent variable) and quantity (the independent variable)

History of Learning Curve

• The concept of the learning curve was introduced to theaircraft industry in 1936 when T. P. Wright published anarticle in the February 1936 Journal of the AeronauticalScience.• Wright described a basic theory for obtaining cost estimates based on repetitive production of airplaneassemblies.• Since then, learning curves (also known as progressfunctions) have been applied to all types of work fromsimple tasks to complex jobs like manufacturing a SpaceShuttle.

Theory of Learning Curve• The theory of learning is recognized that repetition of thesame operation results in less time or effort expended onthat operation.• For the Wright learning curve, the underlying hypothesis is that

the direct labor man-hours necessary to complete a unit of production will decrease by a constant percentage each time the production quantity is doubled.

• If the rate of improvement is 20% between doubledquantities, then the learning percent would be 80% (100-20=80).• While the learning curve emphasizes time, it can be easily

extended to cost as well.

The Learning Curve• Learning Curve - the longer a person performs a task, the quicker it takes himFig 18-2: Estimated cycle times based on a 20% reduction each time the quantity doubles

Learning Effect

Tim

e pe

r re

petit

ion

Number of repetitions

Types of Learning

• Individual LearningImprovement when individuals gain a skill or efficiency by repetition of a job.

• Organizational Learning

Improvement from the groups of individuals from repetition and changes in administration, equipment, and product design.

Learning CurvesAt the start of production runs:– Workers are unfamiliar with their tasks– Time it takes to produce the first few units is

high

As the workers learn their tasks:– Their output per day increases up to a point– Then their output levels off to a rather constant

rate

Learning with ImprovementsT

ime

per

unit

Time

Average Improvements may create ascallop effect in the curve.

Learning Curves

• Most aircraft manufacturing tasks experience an 80% learning rate

• Labor-hours required to assemble an aircraft is reduced by a factor of 0.8 as the production quantity doubles– If first aircraft assembled requires 100 labor-hours– Second aircraft would require 80 labor-hours– Fourth aircraft would require 64 labor-hours– Eighth aircraft would require 51.2 labor-hours– … and so on

Learning Curves

10 20 30 40 50 60 70 80 90 100 11010 20 30 40 50 60 70 80 90 100 110 120 130120 130

2020

8080

4040

100100

6060

Unit Number (Unit Number (nn))

120120

Labor-Hours for Labor-Hours for nnth Unitth Unit

Aircraft AssemblyAircraft Assembly

80% Learning Curve80% Learning Curve

Learning Curves

By analyzing workers’ learning situations, we are able to estimate:– The average number of labor-hours required

per unit for N units in a production run– The total number of labor-hours required to

produce N units in a production run– The exact number of labor-hours required to

produce the nth unit of a production run

Worker Learning Curves

A (underqualified)

B (average)

C (overqualified)

Tim

e/cy

cles

One week

Standard time

Training time

Learning Curve for Mass Production Job

Standard Standard timetime

End of improvementEnd of improvement

Units producedUnits produced

Pro

cess

ing

tim

e p

er u

nit

Pro

cess

ing

tim

e p

er u

nit

Figure 17.7Figure 17.7

• Experience Curve

• Improvement Curve

• Manufacturing Progress Curve

• Cost Curve

• Cost Reduction Curve

Some Other Names of Learning Curves

Learning curve assumptions

• The time required to complete a specified task or unit of aproduct or item will be less each time the task is performed;• The unit time will reduce at a decreasing rate;• The decrease in time will follow a certain pattern, such asnegative exponential distribution shape.• The learning curve may vary one product to another and from

one organization to another. The rate of learning depends on factors such as the quality of management and the potential of the process and products

• The Table presents data on learning curve effects in the U.S.industrial sector . An 80% learning rate is descriptive of certainoperations in such areas as ship construction, electronic dataprocessing equipment, automatic machine production, andaircraft instruments and frame assemblies.• The learning curves are found to be quite useful in a variety ofapplications, including strategic evaluation of company andindustry performance, internal labor forecasting, establishingcosts and budgets, production planning, external purchasing,and subcontracting of items• The learning curve theory is based on a doubling of productivity.More specifically, when output or production doubles, thereduction in time per unit affects the learning curve rate. Forexample, an 80% learning rate means the second unit takes80% of the time of the first unit, the fourth unit takes 80% of thesecond unit, the eighth unit takes 80% of the fourth unit, and so

Curve slope can always be found using the relationship between doubled quantities

Theory = as number of cycles doubles, cycle time decreases by a constant %

Theory

TheoryResult: 20% decrease or 80% learning ratio or 80% learning curve, ormathematicallyy = kxn

• However, easier to plot and calculate if on log-log paperlog10 y = log10k + n×log10 xwhere: y = cycle timex = number of cycles or units producedn = exponential representing the slopek = value of first cycle timeor, rearranging and solving for n:n = log10(learning percent)/log102For 80% learning: n = log10(0.80)/log102=-0.0969/0.301 = -0.322

Theory

Or from the slope:

n = (log10 y1 - log10 y2)/(log10 x1 - log10 x2)

n = (log10 12 - log10 4.92)/(log10 1 - log10 16) = (1.08-.692)/(0-1.204) = -.322

• solve for k, by substituting (1,12) into the main equation yielding k=12,

therefore the final equation for the learning curve:

y = 12 x -.322

Theory

• a) MTM-2 analysis shows a standard time of 2 min. How many cycles does it take to reach it?

• 2 = 12 x -.322

• Then take logs of both sides and solve for x:

log10 (2/12) = -.322 log10 x

log10 x = -.7783/-.322 = 2.417x = antilog 2.417 = 261.3 = 262 (round up!!)

Learning Curves

Three approaches to learning-curve problems are:– Arithmetic analysis– Logarithmic analysis– Learning curve tables

Learning Curves

Arithmetic Analysis

• The simplest approach to learning-curve problems

• If we wish to find the labor-hours required to produce n units, and n just happens to be a number that is one of the doubled values, then this approach works

Example: EZ Machine Shop (A)Learning Curve - Arithmetic Analysis

EZ Machine Shop has a contract to manufacture 100 turbines. The first 20 turbines have been completed. The labor-hours required for a portion of the completed turbines are listed below. Use this data to estimate the shop’s learning rate in manufacturing the turbines.

Unit No. Labor-Hours Unit No. Labor-Hours1 140 5 952 118 10 813 109 15 754 102 20 68

Example: EZ Machine Shop (A)

Learning Curve - Arithmetic Analysis

Compute the learning rate for each of the “doubles”.

Units 1 and 2 118/140 = .8429

Units 2 and 4 102/118 = .8644

Units 5 and 10 81/95 = .8526

Units 10 and 20 68/81 = .8395

(.8429 + .8644 + .8526 + .8395)/4 = .8499

The approximate learning rate is 85%.

Learning Curves

Learning-Curve TablesA table of learning curve coefficients allows us to compute:

• The labor-hours for the nth unit in a production run

• The total labor-hours for the entire production run, where the nth unit is the last unit in the run

Example: EZ Machine Shop (B)

Learning-Curve Tables

The manager of EZ Machine Shop wants a good estimate of the total labor-hours required to manufacture the entire 100 turbines. Also, he is curious about how many labor-hours will be needed for the last (100th) unit. Use the observed 85% learning rate and 140 labor-hours required for the first turbine to compute your estimates.

Example: EZ Machine Shop (B)Learning-Curve Tables

Total Labor-Hours Required for 100 Units= (Hours for 1st unit)(Table total time: 85%, 100th unit)

Look at Table, locate the line for the 100th unit and read across to the Total Time column under the 85% learning rate. The value is 43.75.

Total Labor-Hours Required for 100 Units

= 140(43.75) = 6,125 labor-hours

Example: EZ Machine Shop (B)Learning-Curve Tables

Labor Hours Required for the 100th Unit

= (Hours for 1st unit)(Table unit time: 85%, 100th unit)

In Table, locate the line for the 100th unit and read across to the Unit Time column under the 85% learning rate. The value is .340.

= 140(.340) = 47.6 labor-hours

(100th unit will require 34% of the time 1st unit required)

Learning Curves

Logarithmic Analysis

The following relationship allows us to compute Tn, the labor-hours required to produce the nth unit:

Tn = T1(nb) and b = log r/log 2

where: T1 = labor-hours to produce the first unit

b = slope of the learning curve

b = ln r / ln 2, where r is the percentage rate of improvement

r = learning rate percentage

Example: EZ Machine Shop (C)

Logarithmic Analysis

Compute, using logarithmic analysis, the labor-hours required for the 50th turbine (assuming an 85% learning rate and 140 labor-hours required for the 1st unit).

b = log (.85)/log (2) = - 0.234465253

T50 = 140(50-0.234465253)

= .399623 or .400

(Our result agrees with the value in Table 18.12)

Major Issues in Application

• Selection of Slope

• Rate of Production

• Breaks in Production

• How long does learning go on?

More On Learning Curves

• Not effective for mass production jobs

• Product modifications negate effects

• Improvement can derive from sources besides learning

• Industry-derived learning curve rates may be inappropriate

Some Factors Affecting Improvement Rate

Previous experience Design complexity Labor grades/mix Training/supervision Parts availability Workmanship standards Tooling availability Degree of automation Changes in configuration

Support and services Personnel turnover Rate of production Total quantity Lapses in production Total quantity Schedule fluctuation Parts quality Tolerances Outside influences (e.g., the customer)

Some Problems in Curve Application

• Learning Curves are a technique to help predict the future; they are inherently inexact

• Technique is subjective and judgmental • Frequent misuse • Occasional abuse • Lack of complete understanding by many practitioners