 Hello everyone, I am Chandrakant Rathod working as Assistant Professor in Mechanical Engineering Department, Walchand Institute of Technology, Solapur. Today we are going to start a new topic that is drilling machines. At the end of today's lecture, you are able to understand types of drilling machine, different operations, tools used in drilling machines, coming to the content. The following topic will be discussed in this video lecture, Introduction to Drilling Machine, Classification of Drilling Machine, Tool Holding Device and Drilling and Related Operations, tool used in the drilling machines. So, coming to the introduction to the drilling machines, drilling is the operation of making preliminary hole in a work piece using drill bit. The stationary work is held in a fixture and the rotating tool is feed vertically. Boring is an extension of drilling operations in which the previously drilled hole is enlarged to bigger size using the boring tools. Rimming is basically a finishing operation performed using a rimmer, generally either after drilling or boring. Drilling boring and rimming operations can also be performed in a lathe to a limited size. So, coming to the classification of drilling machines, drilling machines can be classified as follows and we will discuss one by one. First, we will going to list the portable drilling machine, sensitive drilling machine, upright drilling machine, radial drilling machine, gang drilling machine and multiple drilling machine as well as deep hole drilling machines. So, we will going to discuss one by one. First, we will going to take a portable drilling machines. What is mean by portable drilling machines? This is a generally purpose flexible machine tool used for drilling small to medium sized holes. This is generally operation is done by holding in hands while the part of to be drilled being held in a fixture are wise. This machine is most suitable for drilling holes at remote also. The machine is driven by either electrical or pneumatic means. So, coming to the sensitive drilling machines, it is useful for drilling small sized holes by holding the workpiece on its table. This machine is generally small sized with facility to mount it on the bench or on floor depending upon the requirement. It consists of strong vertical column and a horizontal table for fixing the job. In this machine, the head is moved up and down by hand lever for feeding the tool and taking it out. This machine generally runs at high speeds and feeds is controlled by operating the hand lever. Using this machine holes ranging from 1 mm to 15 mm can be drilled. So, coming to the upright drilling machines, this is similar to a sensitive drilling machines in construction with additional features. This machine is larger in size and stronger than a sensitive drilling machines. It has a power feeding mechanism and drive for varying speed, spindle speed to suit various requirements. This machine is used for drilling small and medium sized holes. Based on this type of column, used this machine can be subclassified as round column or pillar type, box column. So, coming to the radial drilling machines. Radial drilling machine is used for drilling medium and large holes. The main advantages of radial drilling machines are the holes at different points and also at different angles can be drilled on a large side job without moving the jobs. So, coming to the GAN drilling machines. This machine consists of number of drill heads placed side by side in line so that more than one holes are a different hole can be drilled on the same job. The advantages of these machines are the series of operations can be done with different spindle mounted with different tools on the same job simply by moving the workpiece from one position to another. So, coming to the multi spindle drilling machines. It is similar to the GAN drilling machines in construction. It is used to drill a number of holes in the same job simultaneously and to reproduce the same in number of similar to job in a mass production. So, coming to the deep hole drilling machine. In this machine the part to be drilled is rotated and the drill bit is kept stationary. This helps in feeding the drill in straight path without any vibration and enlarging the holes. So, coming to the drilling and related operations. So these are the following operations can be discussed as follows. So, first we will going to discuss drilling, rimming, boring, counter boring, countersinking, tapping. So, first we will going to take a drilling. It is the operation of producing cylindrical hole in the solid object using drill. To start a drill operation initially the center of the hole is marked by two cross lines and a center punch is used to highlight the center. The drill point is placed on the center punch mark and drilling is done. Drilling drilled holes have the rough size of the required holes and needs further sizing and finishing operations. So, coming to the rimming. Rimming is a sizing and finishing operations performed in previously drilled hole. For rimming operation a tool called rimming is used. Rimming operations can also be done on holes which are drilled slightly to under size. Coming to the boring operations. Boring is generally a hole enlarging operations performed on a previously drilled hole. Boring is performed in the following circumstance. First to finish a drilled hole. Second one to machine rough surface of the cast holes. The third one is to correct the holes center and roundness of the holes. So, coming to the counter boring. So, please you can pause the video and think that what is mean by counter boring. I think hope you will going to understood that what is mean by counter boring. So, counter boring is the operation of producing a large sized hole at the end of the small sized hole. A hole of small size is first produced by using the normal drilling procedure. Counter bore holes are useful in accommodating the heads of the bolts, studs and pins. So, coming to the countersinking. Counter sinking is the operation of producing a conical shaped hole in a previously drilled cylindrical hole. The tool used for this operation is called as a countersink. Drilling machines holes are useful for accommodating heads of bolts, studs and pins. So, coming to the tapping. Tapping is the operation of producing internal threads in a previously drilled holes. The primary hole is drilled to the core diameter of the threads coming to the tools used in the drilling machines. The important tools used in the drilling machines are as follows. Drills, rimmer, taps. So, first we will going to consider the drills. So, you can see the diagram. First you will going to see the different types of drilled tools. First one is the flat, this is the flat drill and second one is straight fluted drill and third one is the twisted drill and this is the sank which is used for the drilling the operations and this is the taps which is used for the drilling operations. You can see this in the flat drill bit. You can see the first twisted flute. In this one oral length is the sank length and the body length and you will going to see the helical angle and you will going to see the hill and the flute. And you can see in this one oral length is the sank length and the body and you will going to see this one is your resist length and this is the cutting edge of the length. And you can see this third diagram, there the oral length is the sank length and the thread length. So, this is the thread length and you can see this portion is the external center and you can see this one is the chamfer and this inside this one is the internal center. So, you will going to see the detail about this diagram. First we will going to take the flat drill. So it is simple drill bit with v shaped cutting edge. The cutting angle varies from 90 degree to the 120 degree and the relief angle of the cutting edge is around 6 degree. Now coming to the straight fluted drill, it is straight fluted drill flutes that is ground parallel to the drill axis. This is used to drill soft metals and thin sheets. So coming to the twist drill, twist drill is commonly used to tools for making holes. It has two or more twisted flutes on its surface. A twisted drill may have shorter or longer twist portion depending upon the length of the hole to be drilled. So coming to the taps, tap is an internal thread cutting tools and it has a screw surface with shape of the thread similar to that of the thread to be cut. It generally it has four straight flutes across the threads, generally made of high speed steel or high carbon tool steel. Two types of taps are in use that is hand tap and machine tap. So coming to the reference, these are the some references I have used for this lecture that is Foundry Technology by O.P Khanna and Manufacturing Technology by P. N. Rao and Manufacturing Process 1 by A. C. Niranjan. Thank you.