Drilling Process
Drilling is a hole making process for which drill is used as a cutting tool for producing round holes of different sizes and depths.
Drilling machines are subjected for drilling holes, tapping, counter boring, reaming, and general boring operations. Drills may be classified into a large variety of types. Twist drills are the most common tools used in drilling and are made in many sizes and lengths. Lengths range Straight-shank twist drills from 1/60 in diameter to 11/4 in by1/64; 2in by 1/16 in increment. Taper-shank drills range from 1/8 in diam to 13/4 in by 1/64 increments.
The cutting tool used for making holes is called as twist drill. Drill consists two parts. The body consists of cutting edge and the shank used for holding. Two cutting edge and two
opposite spiral are cut into its surface The flute provides clearance to the chips produced at the cutting edge.The surface on the drill that extends behind the cutting tip to the following flute is termed as flank.The face is the portion of the flute surfaceadjacent to the cutting tip on which the chip moves.The land or the margin is the cylindrically ground body surface on the leading edge or flank face.The axial rake angle is the angle between face and the line parallel to the drill axis. Tolerances have been set on the various features of all drills so that the products of different manufacturers will be interchangeable in the user’s plants. Twist drills are decreased in diameter from point to shank (back taper) to prevent binding. If the web is increased gradually in thickness from point to shank to increase the strength, it is customary to reduce the helix angle as it approaches the shank. The shape of the groove is important, the one that gives a straight cutting edge and allows a full curl to the chip being the best. The helix angles of the flutes vary from 100to 450. The standard point angle is 1180. There are a number of drill grinders on the market designed to give the proper angles. The point may be ground either in the standard or the crankshaft geometry.
Drilling is a hole making process for which drill is used as a cutting tool for producing round holes of different sizes and depths.
Drilling machines are subjected for drilling holes, tapping, counter boring, reaming, and general boring operations. Drills may be classified into a large variety of types. Twist drills are the most common tools used in drilling and are made in many sizes and lengths. Lengths range Straight-shank twist drills from 1/60 in diameter to 11/4 in by1/64; 2in by 1/16 in increment. Taper-shank drills range from 1/8 in diam to 13/4 in by 1/64 increments.
The cutting tool used for making holes is called as twist drill. Drill consists two parts. The body consists of cutting edge and the shank used for holding. Two cutting edge and two
opposite spiral are cut into its surface The flute provides clearance to the chips produced at the cutting edge.The surface on the drill that extends behind the cutting tip to the following flute is termed as flank.The face is the portion of the flute surfaceadjacent to the cutting tip on which the chip moves.The land or the margin is the cylindrically ground body surface on the leading edge or flank face.The axial rake angle is the angle between face and the line parallel to the drill axis. Tolerances have been set on the various features of all drills so that the products of different manufacturers will be interchangeable in the user’s plants. Twist drills are decreased in diameter from point to shank (back taper) to prevent binding. If the web is increased gradually in thickness from point to shank to increase the strength, it is customary to reduce the helix angle as it approaches the shank. The shape of the groove is important, the one that gives a straight cutting edge and allows a full curl to the chip being the best. The helix angles of the flutes vary from 100to 450. The standard point angle is 1180. There are a number of drill grinders on the market designed to give the proper angles. The point may be ground either in the standard or the crankshaft geometry.
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