 Hello everyone, this is Shila Ratna Banswade from Walshan Institute of Technology, Solapur. Today we are going to see the topic Interference Fit. Learning Outcomes, students will be able to describe interference fit. At this moment of the video, let us move to the further part. Observe the figures on the screen. This is a hole and a shaft. First case, then second case, this is the hole and the shaft. And the third case, this is the hole and the shaft. So in the first case, you can see the hole is quite bigger as compared to the shaft. In the second case, the difference between the size of the hole and the shaft has been reduced. And in the third case, you can see the size of hole and the size of shaft are nearly equal. So I suggest you to pause the video at this moment and find out where you have seen such kind of arrangements. Or the applications where you see these kind of arrangements. Moving further, fits are used to have joining or to have the degree of tightness or looseness between two parts which are coming in contact with each other. At this first case, this shaft fits loosely in this hole. Here the degree of looseness is bit reduced and here the shaft exactly fits in the hole. So depending upon these cases, the fits are classified. So let us move further. The relation between two mating parts is known as fits. How the two parts are being joined together or come together is known as fits. It is also defined as the degree of tightness or looseness. As we have seen in the previous slide, how the mating parts come in contact. Whether they are in loose contact or whether they are in tight contact. And the degree which decides this is also called as fits. The fits are further classified on the basis of actual limit of the hole or shaft. The fits are classified as clearance fit, interference fit and transition fit. So dipping upon the size of the hole and size of the shaft, clearance fit, interference fit and transition fit are the three types of fits. As far as the current video is concerned, we will be focusing on the interference fit. The clearance fit and transition fit will be covered in the next videos. So let us see the details of interference fit. Interference fit. If the difference between the hole and shaft size is negative before assembly, interference fit is obtained. That means the diameter of shaft should be always or is always greater than the hole diameter. Considering the tolerances, the maximum size of the hole is always less than the minimum size of the shaft. So this is the case where interference fit exists. The meaning of the first sentence is the diameter of shaft is always greater than the hole diameter. This kind of fit is used when you want to transfer power from one shaft to another or you need to have certain kind of motion which needs to be transmitted. Couplings and bearings are fitted on the shaft with the help of this kind of fit or this kind of fit is observed between the bearing and the shaft and the coupling and the shaft. So interference fit exists between the high limit of hole that is the upper limit of the hole and lower limit of the shaft that is the lower limit of the shaft. The size of hole minus the size of shaft is always less than zero and the hole size is always less than the shaft size. Let us move further. Consider this as a zero line. This is the datum line with respect to which we will be measuring the size of the hole or the shaft. This is the maximum size of the shaft. This is the minimum size of the shaft. And the gap between these two is the tolerance. So the red band that you can see on the screen is the tolerance. Now further maximum size of the hole, minimum size of the hole and the gap between these two is the tolerance zone for the hole. So the yellow band that you can see on the screen is the tolerance zone. So you can see that the tolerance zone of hole is always below the tolerance zone of the shaft. So the size of hole is always less than the size of the shaft for interference fit. And this system is known as shaft based system where the size of shaft is fixed whereas the size of hole is varied. That's why the tolerance zone or the maximum tolerance of the shaft is coinciding with the zero line. Whereas the tolerance zone of the hole is below the tolerance zone of the shaft. Let us move further. We have seen how interference fit is represented on the shaft based system. Now let us see how the interference fit is represented on hole based system. So this is the zero line. This is the tolerance zone of the shaft and this is the tolerance zone of the hole. So you can see the minimum tolerance of the hole coincides with the zero line whereas the tolerance zone of the shaft is above the tolerance zone of the hole. This system is called as hole based system. I hope you are clear with this the hole based system and the shaft based system and how interference fit is represented in hole based system and shaft based system. Coming back to the previous. This is the shaft based system and the hole based system. Let us have a comparison between these two. The left hand side of the screen shows the hole based system and the right hand side shows the shaft based system. As far as hole based system is concerned the size of hole is fixed or the tolerance zone of the hole is fixed. Whereas in shaft based system the size of shaft is fixed that is it coincides with the zero line and the size in the hole based system the size of shaft is varied. You can see the red blocks the first the second and the third. This is how the size of shaft or the tolerance zone of shaft is varied whereas the tolerance zone of the hole is kept constant. So this is seen in hole based system. Further the shaft based system. In shaft based system the tolerance zone of the shaft is fixed and it coincides with the zero line and the size of the hole or the tolerance zone of the hole is varied as seen on the screen. So this is one size this is another size and this is the third size as in the first case the size of hole is fixed. It is called as hole based system and in second the size of shaft or the tolerance zone of shaft is fixed it is called as shaft based system. So you can see the size of shaft is always greater in hole based system also it can be seen and the size of shaft is always greater it can also be seen in the shaft based system. So this is representation of interference fit on hole based system and shaft based system. Moving further to find out the minimum and maximum interference. As you can see on the screen this is the shaft and this is the hole. Maximum size of shaft is 30.40, shaft tolerance is this black color gap and minimum diameter of shaft is 30.30. Similar is the case with hole. The hole tolerance is seen with this black color gap. Minimum size of hole is 30.50 and maximum diameter of hole is 30.25. Now to find out the value of minimum interference maximum size of hole minus the minimum size of shaft. Maximum size of hole minus the minimum size of shaft gives you the minimum interference. Whereas for maximum interference the minimum size of hole minus the maximum size of shaft. I repeat for maximum interference the minimum size of hole minus the maximum size of shaft which gives you the maximum interference. So this is how the minimum interference and maximum interference is calculated. These are the references. Thank you.