Page 46 - CITS - Fitter - Trade Theory

FITTER - CITS

Part of drill & functions
1 Shank : This is the driving end of the drill which is fitted on to the machine. Shanks are of two types. Taper
shank, used for larger diameter drills, and straight shank, used for smaller diameter drills.

2 Tang : This is a part of the taper shank drill which fits into the slot of the drilling machine spindle.
3 Body : The portion between the point and the shank is called the body of a drill.
The parts of the body are flute, land/margin, body clearance and web.
4 Flute : Flutes are the spiral grooves which run to the length of the drill. The flutes help.

- To form the cutting edges
- To curl the chips and allow these to come out
- The coolant to flow to the cutting edge.
5 Land : The land/margin is the narrow strip which extends to the entire length of the flutes. The diameter of the
drill is measured across the land/ margin.
6 Body clearance : Body clearance is the part of the body which is reduced in diameter to cut down the friction
between the drill and the hole being drilled
7 Web : Web is the metal column which separates the flutes. It gradually increases in thickness towards the
shank.

8 Point : The cone shaped end which does the cutting is called the point. It consists of a dead centre, lips or
cutting edges, and a heel.
9 Cutting edges : The cone shaped end which does the cutting is called the point. It consists of a dead centre,
lips or cutting edges, and a heel.
10 Heel : Heel which are the trailing edge of the drill point.
11 Dead centre: It is a type of drill bit used for making a starting point or center hole in a workpiece before
drilling with a larger drill bit.
12 Neck: The section of reduced diameter between the body and the shank of a drill.

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CITS : CG & M - Fitter - Lesson 4 CITS : CG & M - Fitter - Lesson 4