MECHENG352 - Work and time study

Question 2

Work measurement techniques

Answer 2

Time study
Work sampling
Predetermined motion & time systems (PMTS)

Question 3

What is time study and how to do it

Answer 3

Time study is a sampling process, so sample size will affect the sampling error.

Need to determine number of cycles:

When making a time study several decisions are made to assure desired results:
* Desired level of accuracy.
* Desired level of confidence for the estimated standard time.
* Number of observations to make.

Desired accuracy level is typically expressed as a % of the mean observed
times.

Question 4

What is work (activity) sampling and how to do it

Answer 4

Work sampling or activity sampling is a technique for estimating the percentage of time that worker spends on various activities.

For jobs that have non-repetitive elements
Also to determine % time worker is delayed or idle

Random observations to record activity

Easier and less expensive than time study

Question 5

Advantages and Disadvantages of Work Sampling

Answer 5

• It is a less expensive procedure.
• Observers with minimal specialized training can conduct the sampling.
• Several operators or machines may be observed simultaneously by a single observer.
• It results in less anxiety and tension among workers.
• There is minimal interference with the worker’s normal routine.
• It measures the utilization of people and equipment directly.
• A work sampling study may be interrupted at any time without affecting the results.

Disadvantages of Work Sampling
* It is not economical for studying a single operator or machine, or for studying
operators or machines located over wide areas.
* It cannot provide a much detailed information .
* It is of little value in helping to improve work methods.
* A lot of groundwork is required.
* 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.

Question 6

Suitability of work sampling

Answer 6

• Group activities
• Non-Repetitive activities with long cycle times (example: maintenance operator, support personnel, etc.),
• Activities that are not rigidly constrained from the time standpoint,
• Heterogeneous activities.

Question 7

What is Predetermined motion time system (PMTS)?

Answer 7

• Predetermined motion time system (PMTS) is a work measurement technique for obtaining a standard time by:
  o analyzing and subdividing a task into elemental motions
  o assigning pre-set standard times for motions and summing these to obtain a
  standard time for the whole task.
• The PMTS database is a set of tables listing time values that correspond to the
  basic motion elements including reach, grasp, move, and release.

Question 8

PMTS types

Answer 8

• Methods -Time Measurement (MTM)
• Work-Factor
• PMTS– Meyers
• Maynard Operation Sequence Technique (MOST)

Question 9

What is the learning curve

Answer 9

• The definition says a doubling of the total number of units made produces a constant decrease in the time per unit
• Learning curves can apply to individual employees or, in an aggregate sense, to the big-picture initiatives such as pricing strategy.
• Learning-curve theory is most applicable to new products or processes that have a high potential for improvement and the benefits will be realized only when appropriate incentives and effective motivational tools are used.
• Organizational changes may also have significant effects on learning (i.e. less motivated staff if they are going to lose their job)
• The learning curve concept is that direct labor unit cost decreases in a predictable manner as the experience in producing the unit increases.
• Although the learning curve theory implies that improvement will continue forever, in actual practice the learning curve flattens out.

Question 10

Practical Issues in Using Learning Curves

Answer 10

• The learning curve does not usually apply to supervisory personnel, some skilled craftspeople, or jobs that have non-repetitive job tasks.
• A change in the ratio of indirect labor or supervisory talent to direct labor can alter the rate of learning.
• The institution of incentive systems, bonus plans, quality initiatives, empowerment, and the like may increase learning.
• Changes in product design, raw material usage, technology, and/or the process may significantly alter the learning curve.
• A contract phase out may result in a lengthening of processing times for the last units produced, since employees want to prolong their income period.
• The lack of proper maintenance of tools and equipment, the non-replacement of tools, or the aging of equipment can have a negative impact on learning.
• Keeping groups of employees together, such as highly specialized consulting groups, reaps a productivity benefit but may affect innovation and new experiences.
• The transfer of employees may result in an interruption or a regression to an earlier stage of the learning curve or may require a new learning curve.
• Learning curves focus on direct labor and ignore indirect labor that also contributes to efficiency and effectiveness.