4. Time Study

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4. Time Study

• The major objective of this chapter is to learn
  how to calculate a time standard based on
  stopwatch time study procedures.

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Time Study

• A process for measuring the required time for
  performing a given task, by a given method, by a
  trained worker, working in a normal pace.

• Why needed?
• For methods improvement
• For determining time standards

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Needs for Time Standard

• Developing schedules
• Determining wage payment plans
• Estimating production costs
• Providing a base for estimating productivity
  goals
• Appraising employee performance
• Evaluating alternative process, equipment

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Methods for Creating Time Standards

• Direct time study
• Cyclic work
• Non cyclic work
• Work sampling
• Synthetic data
• Predetermined times

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Direct Time Study - Tools
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Direct Time Study

• Methods improvement
• Selection of the examined workers
• Explanation (union, managers, workers)
• Collecting and recording information
• Task division into elements

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Methodology

• Who to choose?
• Select an Average Worker (What is average?)
• Experienced operator
• Normal pace
• Consistency (well defined, understood by all)
• No undue strain for entire day (speed/effort)
• Pace that should be performed, not average of
  current rate
• Rating accuracy
• Worker acceptance
• Can you suggest a better method?

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Preparation for Timing

• Identify the TASK/ CYCLE to be studied before
  time study
• Analyze the Complete Task
• Method
• Layout of workplace
• Equipment used
• Environmental conditions
• Machine speeds and feeds
• Inspection equipment
• Communications with foreman, workers
• Documents for process, task instructions
• Establish relationship
• Elemental analysis
• Break task into elements

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Fundamental definitions

• What is an ELEMENT?
• Element is a component of job or task that are
  logical divisions with easily identifiable
  starting and end points, and are repeated on a
  regular basis
• What is a CYCLE?
• Cycle is the completion of the activities
  (elements) required to perform the job under
  study.

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Element Analysis

• Every element must have an easily identifiable
  starting and ending point (breakpoints)
• No discontinuities between elements
• Elements times 0.04min (short), 0.25min
  (reasonable)
• Relative frequency must be included

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Timing Methods

• Continuous
• Advantage Clock never stops, no time omitted
• Disadvantage observer does not know at the job
  how individual elements vary
• Snapback
• Advantage Observer can note individual
  variability within an element and eliminate
  substraction
• Disadvantages difficult to coordinate eye, watch
  and task! Especially when operations are short

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Determining Number of Cycles

• Time measurement
• Measuring time of each element
• The number of observation of each element depends
  on the significance level and required level of
  accuracy

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Recommended number of cycles/observations
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Maytag Company Approach
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(No Transcript)
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Rules for Performing Time Study

• Dont comment to the worker during the task
• Stand (dont sit) beside the worker
• Write every event (even though it may seems not
  important)
• Have a good position to observe
• Stop the study if the worker seems to be under
  pressure and it affects his/her work

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Time Study On Cyclic Work

• Rating evaluation may be written once in a couple
  of cycles
• Elements times 0.04min (short), 0.25min
  (reasonable)
• Denoting non-cyclic elements
• The breakpoint between elements should be clear
  (touch, push, etc.).

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Types of Elements

• Manual/machine (determines the task duration)
• Cyclic/non cyclic
• Fixed time/ variable time (i.e. loading time as a
  function of weight)
• Avoidable/unavoidable unproductive elements
  (sometimes hard to identify)

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Time Study on Non Cyclic Work

• Use continuous timing
• Divide the task into relatively large elements
• Write the evaluated performance rate at the end
  of each element
• Multiply the observed time with the rate and
  summarize the data

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RATING FACTORS
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Do we expect the average worker to work in normal
rating ?
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Rating Evaluation Methods

• Subjective judgment
• Practice by watching movies
• For a study with long elements, rate each
  separately
• Methods
• Speed rating
• Westinghouse

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Performance Rating Table (Westinghouse)
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Criteria for Successful Speed Rating Evaluation

• Experience in the class of work performed
• Selection of an operator who gives performances
  between 85 and 115
• Use of the average value of three or more
  independent studies

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Elements of Allowances
Extra Allowances
Unavoidable Delays
Basic Fatigue
Personal Need
Variable Fatigue
Avoidable Delays
Special Allowances
Constant Allowances
Normal Time
Standard Time
Total Allowances Allowances


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Standard Data Systems

• Elemental times, based on previous time studies,
  which have been proven to be accurate and
  reliable.
• Tabulated element standards that allow the
  measurement of a specific job without the use of
  timing devices.

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Construction Cost Estimating
Given we have the plans for a new building, how
much labor is needed and what will it be used for?
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Punch Press Standard Data(40 strip)
Given we have a new part to run through the punch
press, what will be the standard time for the
part?
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Advantages Over Direct Time Study

• More consistent standards results
• Duplicate time studies on similar operations are
  eliminated
• Standards are established more rapidly
• Less experienced analysts can calculate standards
  (use the formula not develop it)
• Accurate labor costs and production times can be
  estimated before production begins

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To Illustrate the development of standard data
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Possible Drivers
Model NT 3/4/5 D1 D2
119 15.72 18.00 27.25 130 16.88 23.50 33.50
220 10.62 2.50 1.50 310 11.06 3.00
7.25 311 18.47 25.00 44.00 322 12.34 12.00 18.
25 329 11.35 3.00 8.00
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Correlation
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Is there a relationship between D1 and the
combined time for elements 30, 40, and 50?
n X1 X2 X12 X22
X1X2 1 15.72 18.00 247.1184 324.00
282.96 2 16.88 23.50 284.9344 552.25
396.68 3 10.62 2.50 112.7844 6.25
26.55 4 11.06 3.00 122.3236 9.00
33.18 5 18.47 25.00 341.1409 625.00
461.75 6 12.34 12.00 152.2756 144.00
148.08 7 11.35 3.00 128.8225 9.00
34.05 Sums 96.44 87.00 1389.3998
1669.50 1383.25
r 0.977
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Linear Regression
Y b0 b1X
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Standard Times for Machining Operations

• How long will it take to drill a 1-inch hole
  through two inches of malleable cast iron?