Lesson 13 - Time Study

• Time study


  A work measurement technique for recording the time of performing a certain specific job or its element carried out under specific condition and for analyzing the data so as to obtain the time necessary for an operator to carry at a defined rate of performance
• Time study


  A method of direct observation where a trained observer watches the job and records data as the job is being performed over a number of cycles
• Time study was first developed by Fredrick Winslow Taylor
• Reasons for time study

  • The job in question is a new one, not previously carried out
  • A change in material or method of working has been made and new time standard is required
  • A complaint has been received from a worker or worker's representative about the time standard for an operation
  • A particular operation appears to be a "bottleneck" holding up subsequent operations and possibly previous operations
• Points to be observed before the study

  • Make sure the job has been method studied, especially when the standard time is to be used for incentive purposes
  • In an organization where time study has never been used before, supervision and worker representatives should be told the reasons for the study program and given insight into the study procedure
  • It is good policy to ask the supervisor or workers representatives to be studied
  • The worker should be a competent steady person with an average rate of working
  • The worker should be told the reasons for the study and asked to work at their normal pace
• Points to be observed before the study (continued)

  • Workers should be allowed plenty of time to settle down to new methods
  • The observer should take a position where they can see the whole of the job being performed, generally to the side of the operator, slightly to the rear and approximately 6 feet away
• Time study equipment


  • Stop watch
  • Observation sheet or form
  • Clip board
  • Ball pen
• Phases of a time study


  1. Analysis phase: Obtain and record operator, working condition, methods, breakdown tasks to elements

  2. Measurement phase: Observe/record the task, rate operator performance

  3. Synthesis

  4. Reporting and Standard Update
• Normal operator


  Adapted to the work and has sufficient experience, has coordinated mental and physical abilities, maintains proper use of equipment and tools related to the job, is cooperative, performs a pace best suited for continuous performance
• Element


  A distinct part of a specified job
• Work cycle


  The sequence of elements which are required to perform a job
• Performance rating


  The procedure in which the time study engineer compares the performance of operator(s) under observation to the normal performance and determines a factor called rating factor
• Systems of rating

  • Pace rating
  • Westinghouse system of rating
  • Objective rating
  • Synthetic rating
• Pace rating


  Operator's performance is evaluated by considering their rate of accomplishment of the work, measured against the concept of normal performance
• Westinghouse system of rating


  Considers four factors in evaluating the performance of operator: skill, effort, conditions, and consistency
• Objective rating


  Speed of movements and job difficulty are rated separately and combined into a single value
• Synthetic rating


  Does not rely on the judgment of time study person and gives consistent results, uses predetermined motion time system to estimate performance factor
• A


  Average actual observed time of the element
• Overall rating factor


  The mean of rating factors determined for the selected elements, applied uniformly to all the manually controlled elements of the work cycle

  
• Example Computation for Synthetic Rating

  1. Divide work cycle into elements

  2. Conduct time study

  3. Select manually controlled elements

  4. Determine rating factors for selected elements

  5. Calculate mean of rating factors
• Power controlled (or machine-paced) elements are always given 100% rating
• Allowances


  • Constant allowances (for personal needs and basic fatigue)
  • Delay Allowance (for unavoidable delays)
  • Fatigue Allowance (for job dependent fatigue)
  • Personal Allowance
  • Special Allowance
• Delay Allowance


  Time allowance given to operator for the numerous unavoidable delays and interruptions experienced during work
• Fatigue Allowance


  Allowance given to compensate for the energy expended for carrying out the work and to alleviate monotony
• Basic fatigue allowance


  Constant allowance for light work while seated, under good working conditions and under normal demands
• Variable fatigue allowance


  Allowance that depends on the severity of conditions that cause extra fatigue
• Personal Allowance


  Allowance to compensate for the time spent by worker in meeting physical needs
• Special Allowances


  • Policy Allowance
  • Small Lot Allowance
  • Training Allowance
  • Rework Allowance
• Computation of the Standard Time

  1. Determine total average cycle time

  2. Discard abnormal time values

  3. Calculate normal time

  4. Calculate standard time
• Watch readings falling 50% above and 25% below the average may be considered as abnormal

  
• Normal time = Observed time x Performance rating
• Standard time = Normal time + Allowances
• Statistical Method of Sample Size

  • Accuracy Desired
  • Confidence Desired
  • Data Variability
• Pace Rating


  In this method, which is also called the speed rating method, the time study person judges the operator's speed of movements, i.e. the rate at which he is applying himself, or in other words "how fast" the operator performs the motions involved.