Friday, 20 December 2019

We have started a new topic in our previous post i.e. engineering mechanics. We have seen there the basic concept of force system, fundamentals of work, basic concept of truss in engineering mechanics and we have also discussed there the process to solve the truss problems using method of joints and method of sections with the help of our previous post.

Now, we will be interested here to understand the positive and negative effects of friction with the help of this post. We will see here the positive and negative effects of friction in various applications and further we will find out the classifications of friction in our next post.

Let us first understand the importance i.e. positive and negative features of friction in various areas.

Importance of friction

If we first look out here the positive features of friction, we can easily say that friction plays a very important role in our daily lives and it could be concluded by considering the following points.

Areas where friction will be required

Friction help us to walk. If there will be no friction, we can not walk.

Friction play a positive role in braking system. You can assume any automobile such as one bike and if you are driving the bike and you need to stop it or you need to reduce the speed of bike, you will apply the brakes. Brake shoe will come in contact with rotating wheel once you will apply the brake. Due to friction, rotating wheel will be stopped or its speed will be reduced.

There are various applications where we can see the power transmission from one machine to another machine with the help of V-belts, without friction V belt will not be able to transmit the power from one machine to another machine.

You can also feel one experience of driving a bike on road, without friction we can not even run the bike on road. If you imagine that you are driving a bike in rainy season on a muddy road, your bike will be slipped as friction will be reduced there due to presence of muddy road in rainy season.

So, there are various positive features of friction in our daily lives and in engineering areas too.

Areas where friction is undesirable

Now let us find out here some negative features of friction, as mentioned below, where you feel that friction is playing a negative role in the application and you need to spend a lot of money to reduce the negative effect of friction in those applications.

In automobile sectors, we can consider the example of IC engine. In IC engine, there will be friction between the cylinder and its piston and automobile industries are spending a lot of money to reduce the friction by using the principle of lubrication.

We can also consider the example of bearings where lubrication will be needed in order to avoid the metal to metal contact and to reduce the negative effect of friction. By lubrication, friction negative effect will be reduced.

You can find out here the detailed post for lubrication of bearing and its fundamentals and also need of lubrication.
You can also consider the example of a gear box where the approximate 50 % parts of internal gears of gear box will be in the oil sump and these internal gears of gear box will be driven within the oil sump.

Normally Gear oil 320 is used for lubricating the internal gears of a gear box in order to reduce the negative effect of friction such as to reduce the heat energy, noise etc. Correct lubrication practice will surely increase the service life of rotating components of a gear box such as gears, bearings etc.
You can find out the detailed post about the fundamentals of gears and gear box.

Classifications of friction

We will classify the friction as mentioned below.

We will find out the detailed post based on the classifications of friction in our next post.

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Reference:

Engineering Mechanics, By Prof K. Ramesh