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Drilling Process This is the operation of making a circular hole by removing a

volume of metal from the workpiece by a rotating cutting toolcalled drill.

Drilling removes solid metal from the work piece to produce a

circular hole.

Before drilling, the hole is located by drawing two lines at rightangle and a center punch is used to make an indentation for the

drill point at the center to help the drill in getting started.

A suitable drill is held in the drill machine and the drill machine is

adjusted to operate at the correct cutting speed.

The rotating drill is made to feed into the workpiece .

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Boring Process This operation is carried out using cutting tools with only one

cutting edge, where enlarging a hole by means of adjustable isaccomplished.

A boring tool is employed using turning machine.

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A twist drill has three

principal parts:

(i ) Dri l l point or dead center

(i i ) Body

(ii i) Shank

Drills are made of high

speed steel. High speedsteel is used for about 90

per cent of all twist drills.

For metals more difficult

to cut, HSS alloys of highcobalt series are used.

Twist Drill

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Drilling Machines

1. Base

2. Pillar

3. Worktable

4. Motor5. Hand wheel

6. Quill

7. Spindle

8. Depth stop

9. Stop/start

10. Drill guard

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Drilling Machine

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Drilling Machines

Radial DrillUpright Drill

Bench Drill

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Drilling Machines

Upright Drill:

It is a heavy duty type of drilling machine normallyincorporating a geared drive spindle head. Thistype of drilling machine is used on large hole-producing operations that typically involve largeror heavier parts.

The upright drill allows the operator to hand feedor power feed the tool into the workpiece.

The power feed mechanism automatically advancesthe tool into the workpiece.

Some types of upright drill are also manufacturedwith automatic table-raising mechanisms.

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Drilling Machines

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Drilling Machines

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Drilling MachinesRadial Drill:

It allows the operator to position the spindle directlyover the workpiece rather than move the workpiece tothe tool.

The design of the radial drill press gives it a great deal

of versatility, especially on parts too large to positioneasily.

Radial drills offer power feed on the spindle, as well asan automatic mechanism to raise or lower the radialarm.

The wheel head, which is located on the radial arm canalso be traversed along the arm, giving the machineadded ease of use as well as versatility. Radial arm drill

presses can be equipped with a tilting table.

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Types of Twist Drill

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Tool holding

Drill chuck

Safety chuck key

Drift in drill spindle

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Removing a drill from drill machine

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For large diameters a 'hole saw' can be used. The advantage

of this type of drill bit is that the blade can be changed to

give different sizes of diameter.

Hole Saw

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Reaming Process Reaming is performed by means of a cutting tool called reamer

Reaming operation is performed by means of a multitooth toolcalled reamer. Reamer possesses several cutting edges on outer

periphery

This process serves to make the hole smooth, straight and accurate

in diameter..

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Other operations Counter Boring: is the operation of enlarging the end of a hole

cylindrically, as for the recess for a counter-sunk rivet.

Counter sinking:This is the operation of making a cone shaped

enlargement of the end of a hole. This is done for providing a seat

for flat headed

Tapping Counter boring Counter sinking

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Shaper

Principal components of a shaper

Shaper is a reciprocating type of machine tool in which the ram

moves the cutting tool backwards and forwards in a straight line.

The basic components of shaper are shown below.

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Shaper

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