Rating in Time and Motion study

This article explains what is rating and how to do rating in time and motion study. This article is related to the article on Direct stopwatch time study, which explains about how to do time study.

Ok let’s dive into our subject.

What is rating

Rating is the one of the steps conducted during time and motion study, for arriving normal time. How rating is used to arrive normal time is explained in the article, Direct stopwatch time study.

Rating is the comparison of speed of movement of body parts of operator, while doing an activity, with a standard level of speed, by the time study analyst.

How to do rating

Before knowing how to do rating, we must know what is standard level of speed.

Standard level of speed is the speed at which the limbs of a human move while he is walking at 6.4 km per hour on a level ground without any load.

Another standard level of speed is speed of movement of hands of a human while dealing with 52 playing cards in 22.5 seconds.

These two standards are mentioned in the ‘Introduction to work study’ book of ILO.

You may conduct experience with these standards and learn these standard so that you can apply this in rating. You may need to change slight variations to these standard, for achieving the aim of time rating (aim described in last section of this article).

After experiments, you will be having standard level of speed in your mind. Now, just compare this speed with the actual speed of working of the operator while doing an activity.

If the operator does an activity with half the standard speed in your mind, give a rating of 50. This rating is called observed rating.

If the operator does an activity with double the standard speed, observed rating will be 200.

In this way observed rating can be 50, 60, 70, 80, 90, 120, 130, 150, etc.

100 will be the standard rating, which is given to the standard level of speed.

Once we got the observed rating we have done with the rating. And this is used for calculating rating factor and hence the standard time, which is explained in the article on Direct stopwatch time study.

We have used speed or pace rating method here, which is most simplest and common method of rating.

Other methods are skill rating, effort rating, etc.

I hope you understood the concept of rating.

What is the purpose of rating

There will be a large variation in time taken to complete an activity when done manually, during the day and from even day to day. And also our aim is to arrive cycle time in which is an average of actual cycle time for an activity, when done by an operator who has all the required knowledge and skill for doing that activity and he is self motivated. The best method to do is to take large no of observations, which is practically not possible and uneconomical. Hence the rating.

Also, there is chance of intentionally slowing down or speeding up of an activity.

No need to apply rating to machine element.

You can use our free online time study sheet.

Thank you.

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