29-08-2016, 11:31 AM
1451368035-7METHODSTUDY.docx (Size: 35.59 KB / Downloads: 6)
The approach to method study
Method study was defined in Chapter 3. It may be useful, however, to recapitulate this definition. Method study is the systematic recording and critical examination of ways of doing things in order to make improvements, the basic approach to method study consists of the following eight steps:
1. SELECT the work to be studied and define its boundaries.
2. RECORD the relevant facts about the job by direct observation and collect such additional data as may be needed from appropriate sources.
3. EXAMINE the way the job is being performed and challenge its purpose, place, sequence and method of performance.
4. DEVELOP the most practical, economic and effective method, drawing on the contributions of those concerned.
5. EVALUATE different alternatives to developing a new improved method comparing the cost-effectiveness of the selected new method with the current method of performance.
6. DEFINE the new method, as a result, in a clear manner and present it to those concerned, i.e. management, supervisors and workers.
7. INSTALL the new method as a standard practice and train the persons involved in applying it.
8. MAINTAIN the new method and introduce control procedures to prevent a drifting back to the previous method of work.
Motion study
In certain types of operation, and particularly those with very short cycles which are repeated many times over, it may be worthwhile going into much greater detail to determine where movements and efforts can be saved and to develop the best possible pattern of movement, thus enabling the operative to perform the operation repeatedly with a minimum of effort and fatigue. The techniques used for this purpose are known collectively as micro motion study. In the earlier periods of work study special types of chart such as the same chart, as well as special micro motion symbols known as therbligs, were used for micro motion study. These have now been replaced by the use of Predetermined Time Standards charts (PTS charts), which will be explained in Part Four of this book, as well as by the use of film and video. Both film and video cameras can be used to record activities at the workplace. Although film provides greater flexibility in terms of filming and playback speeds, video is generally cheaper and easier to use. With a good- quality video playback unit, it is possible to have high-quality slow motion and still-frame facilities.
The advantages of film and video over direct observation are that they:
(a) Permit greater detailing than eye observation;
(b) Provide greater accuracy than pencil, paper and watch techniques;
© More convenient;
(d) Provide a positive record;
(e) Help in the development of the work study persons themselves
The purpose of work measurement
It is observer that total time of manufacture of an article was increased by undesirable features of the product itself, by a poorly designed process and by ineffective time added in the course of production and by actions due to the human element. All these factors tended to reduce the productivity of the enterprise.
Method study is the principal technique for reducing the work involved, primarily by eliminating unnecessary movement on the part of material or operatives and by substituting good methods for poor ones. Work measurement is concerned with investigating, reducing and subsequently eliminating ineffective time, that is time during which no effective work is being performed, whatever the cause.
(7. 1) STUDY OF PERFORMANCE RATING BY WALKING
Rating is comparison of work observed by the work study man with a standard level that he has been trained to visualize i.e. the assessment of the rate of the work with respect to standard level.
The term standard level means the average at which a qualified worker will naturally work on a job when using the prescribed method and also is motivated to apply them. This is also known as standard normal rating denoted by 100 on the rating scale.
The qualified worker means one who is accepted as having necessary physical attributes, who possesses the required intelligence, education and has acquired the necessary skill and knowledge to carry out work in hand to satisfy quality, quantity and safety.Theoretically,
Normal Time = Observed Time* Rating.
In actual practice the multiple “observed time* rating” will not be exactly constant, when taken over a large number of readings if the following causes are present.
1. Variation in work element.
2. Inaccuracies in noting and recording observed time.
3. Inaccuracies in rating.
4. Variation due to rating to the nearest ten points.
PROCEDURE:
1. Select a room with smooth level floor, Measure off 15m of unobstructed floor space marking starting and stopping lines.
2. One of the student/ operator will practice walking 15m at exactly v km/h. The student/ operator will take t time to walk 15m at v speed. Other students will mean while observe the limb movement (hand and legs) of the operator to get a picture of the speed at standard pace.
This practice will continue for long time to grasp the concept of normal pace in their mind. For this purpose the operator walk at v speed and the group is told that this speed represents the rating factor of 100%. Several trials are made at this speed.
3. Each operator will walk 15m for 5 times, each time with varying speed at random. One student will record the actual time taken to walk 15m, while all other students record their rating in percent. The walking speed should fall approximately between 85% to 150% of normal because working speed in practice is usually within these limits.
4. Each student in turn, act as an operator and step III is repeated each time.
5. A graph of actual rating v/s his estimated rating is drawn by each student.