Time Studies

1
Time Studies

• Used to determine the time required by a
  qualified and well-trained person working at a
  normal pace to do a specified task.
• T.S. involves measurement motion studies involve
  design.

2
Uses for Time Studies

• Determining standard costs and as an aid in
  preparing budgets.
• Determining schedules and planning work.
• Estimating the cost of a product before mfg.
• Determining machine effectiveness.
• Determining wage incentives for direct and
  indirect labor.

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Lets Look at the Three Work Analysis Tools

• Work Measurement
• 1. Time Studies Chapter 28
• 2. Motion Analysis or Predetermined Time Systems
  (MODAPTS) Chapter 29 Instructor Notes
• With both of the above, we need to consider
  Allowances Chapter 27
• Occurrence Sampling Chapter 10

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How do the Three Work Analysis Tools Compare?

• Time Studies segmental measurement of actual
  work done by direct, continuous observation
• Motion Analysis segmental calculation of actual
  or planned work from predetermined times
  associated with standard motions
• Occurrence Sampling periodic sampling of work
  activities to create work estimate

5
Nonengineered Time Studies

• These are TEMPORARY estimates known as Type II
  estimates.
• Should be set to expire automatically after no
  more than 60 days.
• Expressed as DID TAKE (x units of time/unit), as
  opposed to SHOULD TAKE

6
Sources of Type II Estimates

• Historical records - production rate/ employees
• Expert opinion - get supervisor opinion of rate
• Time logs - Records of time allocation
• may omit small jobs
• may be modified to add to 8 hr/day
• may be deliberately biased
• Occurrence Sampling - data gathered over time
  with allowance added in with work times.

7
Is the Job Ready for a Time Study?

• Need correct method
• Materials in specification
• Correct machine speed
• All other conditions of work in standard settings
• Lastly, would a motion study bring about
  improvements?

8
During the Time Study

• The time analyst should ask (for each phase)
• Can the speed or feed be increased w/o hurting
  quality?
• Can changes in tooling decrease cycle time?
• Can materials be moved closer to work area?
• Is equipment operating correctly, and a quality
  product being produced?
• Is the operation being performed safely?

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Overview of Time Study (Type I)

• 1. Secure and record information about the
  operation and operator being studied.
• 2. Orient the supervisor and the workers.
• 3. Improve the work methods.
• 4. Break the task into elements and record.
• 5. Observe and record the time taken by the
  operator.
• 6. Determine the number of cycles to be timed.
• 7. Rate the operators performance.

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Overview (cont.)

• 8. Check to make certain that a sufficient number
  of cycles have been recorded.
• 9. Determine the allowances.
• 10. Determine the time standard for the
  operation.
• 11. Check and debug the standards with audits.
• 12. Implement with recall review in one month.

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Reasons for Element Breakdown

• Data is more readily reusable when each element
  is described separately, esp. beginning and
  ending points.
• Standard (estimated) time values may be
  determined.
• Individual elements may be excessively short
  (e.g., inspection), or too long. These can be
  picked out more easily in element form.
• This allows for separate performance ratings for
  each.

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Dividing an Operation into Elements

• 1. The elements should be as short in duration as
  can be accurately timed. (Not in individual hand
  motions, which are too short to time.)
• 2. Handling time should be separated from machine
  time.
• 3. Constant elements should be separated from
  var-iable elements (i.e., those that are size
  dependent).
• 4. Regular elements are recorded first, then all
  others.

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Taking and Recording of Data

• Continuous timing - records readings at the end
  of each element as watch runs
• Repetitive timing - after recording, watch is
  snapped back to zero at the end of each element
• Multiple watches - connected by a lever one
  runs, another is stopped, another set to go
• Electronic watch - may continue in split mode

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Advantages and Disadvantages of Work Sampling

• Advantages (of Work Sampling vs. Time Study)
• 1. Many operations or activities, which are
  impractical or costly to measure by time study,
  can readily be measured by work sampling.
• 2. A simultaneous work sampling study of several
  operators or machines may be made by a single
  observer. Ordinarily an analyst is needed for
  each operator or machine when continuous time
  studies are made.

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Advantages (cont.)

• 3. It usually requires fewer man-hours and costs
  less to make a work sampling study than it does
  to make a continuous time study. The cost may be
  as little as 5 to 50 percent of the cost of
  continuous time study.
• 4. Observations may be taken over a period of
  days or weeks, thus decreasing the chance of
  day-to-day or week-to-week variations affecting
  the results.

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Advantages (cont.)

• 5. It is not necessary to use trained time study
  analysts as observers for work sampling studies
  unless performance sampling is required. If a
  time standard or a performance index is to be
  established, however, then an experienced time
  study analyst must be used.
• 6. A work sampling study may be interrupted at
  any time without affecting the results.
• 7. Work sampling measurements may be made with a
  preassigned degree of reliability. Thus, the
  results are more meaningful to those not
  conversant with the methods used in collecting
  the information.

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Advantages (cont.)

• 8. With work sampling the analyst makes an
  instantaneous observation of the operator at
  random intervals during the working day, thus
  making prolonged time studies unnecessary.
• 9. Work sampling studies are less fatiguing and
  less tedious to make on the part of the observer.

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Advantages (cont.)

• 10. Work sampling studies are preferred to
  continuous time studies by the operators being
  studied. Some people do not like to be observed
  continuously for long periods of time.
• 11. A stop watch is not needed for work sampling
  studies. If an electronic data collector is used
  the results are shown on a computer printout.

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Advantages and Disadvantages of Work Sampling

• Disadvantages (of Work Sampling vs. Time Study)
• 1. Ordinarily work sampling is not economical for
  studying a single operator or machine, or for
  studying operators or machines located over wide
  areas. The observer spends too much time walking
  to and from the work place or walking from one
  work place to another. Also, time study,
  standard data, or predetermined time data are
  preferred for establishing time standards for
  short-cycle repetitive operations.

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Disadvantages

• 2. Time study permits a finer breakdown of
  activities and delays than is possible with work
  sampling. Work sampling cannot provide as much
  detailed information as one can get from time
  study.
• 3. The operator may change his or her work
  pattern upon sight of the observer. If this
  occurs, the results of such a work sampling study
  may be of little value.

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Disadvantages

• 4. A work sampling study made of a group
  obviously presents average results, and there is
  no information as to the magnitude of the
  individual differences.
• 5. Management and workers may not understand
  statistical work sampling as readily as they do
  time study.
• 6. In certain kinds of work sampling studies, no
  record is made of the method used by the
  operator. Therefore, an entirely new study must
  be made when a method change occurs in any
  element.

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Disadvantages

• 7. There is a tendency on the part of some
  observers to minimize the importance of following
  the fundamental principles of work sampling, such
  as the proper sample size for a given degree of
  accuracy, randomness in making the observations,
  instantaneous observation at the preassigned
  location, and careful definition of the elements
  or subdivisions or work or delay before the study
  is started.

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Additional Tips

• Is made easier -if end of element is accompanied
  by a sound (e.g., dropped a shaft into a jig)
• Foreign elements - should be timed and recorded.
  Theyll be included if logical to do so. Examples
  include putting oil on a tight screw in a jig,
  accidentally dropping a wrench, etc.

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Number of Observations

• Take at least 10 good readings for cycles of 2
  minutes or less take at least 5 good reading for
  cycles greater than 2 minutes
• Determine this sub-sample standard deviation to
  assist in determining number of actual samples
  needed