Mechanical Engineering Mechanical Engineering Technology.Technology.

Topic: Drilling.Topic: Drilling.

WELCOMEWELCOME

Topic: Drilling.Topic: Drilling. Objectives: Students should be able to:Objectives: Students should be able to: 1. State the definition for drilling1. State the definition for drilling 2.identify the parts of the drilling machine.2.identify the parts of the drilling machine. 3. identify three types of drilling Machines3. identify three types of drilling Machines 4. State at least five (5) safety precautions 4. State at least five (5) safety precautions

that are associated with the drilling that are associated with the drilling machine. machine.

Mechanical Engineering Mechanical Engineering Technology.Technology.

Drilling machines, also called drill presses, cut holes in metal with a twist drill. They also use a variety of other cutting tools to perform the following basic hole-machining operations: (1) reaming, (2) boring, (3) counter-boring, (4) countersinking, and (5) tapping internal threads with the use of a tapping attachment

DrillingDrilling

Drilling is the process of cutting Drilling is the process of cutting holes in metals by using a drilling holes in metals by using a drilling machine.machine.

Drills are the tools used to cut Drills are the tools used to cut away fine shavings of material as away fine shavings of material as the drill advances in a rotational the drill advances in a rotational motion through the material. motion through the material.

DrillingDrilling

BoringBoringBoring.Boring. Boring always Boring always

involves the enlarging of involves the enlarging of an existing hole, which an existing hole, which may have been made by a may have been made by a drill or may be the result of drill or may be the result of a core in a casting. a core in a casting.

Pedestal Type Drilling Machine

Drilling Machines

Radial Drilling Machine

CNC Drilling Machine

Parts of the Bench Drilling Parts of the Bench Drilling MachineMachine

Drilling Machine.Drilling Machine.

DriveDriveAn electric motor provides the An electric motor provides the

drive through belt and pulley to the drive through belt and pulley to the spindle. The range of speeds will spindle. The range of speeds will vary with different sizes and makes vary with different sizes and makes of machines from 4 to 10, a typical of machines from 4 to 10, a typical speed range being 300 r.p.m. to speed range being 300 r.p.m. to 2000 r.p.m.2000 r.p.m.

The TableThe TableMade of cast iron, may be circular Made of cast iron, may be circular

or rectangular in shape and is or rectangular in shape and is provided with slots to allow for the provided with slots to allow for the bolting down of the vice or bolting down of the vice or workpiece. The table may be workpiece. The table may be locked at any position on the locked at any position on the column and is sometimes capable column and is sometimes capable of being swung round and locked of being swung round and locked at any desired angle.at any desired angle.

Precautions For Drilling.Precautions For Drilling. Twist drill must be clamped in the Twist drill must be clamped in the

drill chuck tightly drill chuck tightly The workpiece to be drilled must The workpiece to be drilled must

be firmly secured by vice, or be firmly secured by vice, or clamps. clamps.

Drill guard must be closed before Drill guard must be closed before switch on the machine. switch on the machine.

Precautions cont.Precautions cont.Use the correct drilling speed and Use the correct drilling speed and

apply suitable drilling force It is apply suitable drilling force It is advisable to release the drill advisable to release the drill occasionally, lift the drill, and clear occasionally, lift the drill, and clear the hole of cutting. the hole of cutting.

Apply cutting fluid in the cutting Apply cutting fluid in the cutting except for drilling Cast iron. except for drilling Cast iron.

Take care, when the drill is nearly Take care, when the drill is nearly penetrated through the workpiece. penetrated through the workpiece.

Twist Drill The twist drill is made from The twist drill is made from

High Speed Steel, tempered to High Speed Steel, tempered to give maximum hardness give maximum hardness throughout the parallel cutting throughout the parallel cutting portion. portion.

Twist Drill Twist Drill

Twist DrillsTwist Drills

FlutesFlutes. Flutes are incorporated to . Flutes are incorporated to

carry away the chips of metal carry away the chips of metal and the outside surface is and the outside surface is relieved to produce a cutting relieved to produce a cutting edge along the leading side of edge along the leading side of each flute. each flute.

Drill Features Drill Features

The point of the drill is ground The point of the drill is ground to an angle of 59 degrees to the to an angle of 59 degrees to the centre line to give two equal centre line to give two equal cutting edges, and each side is cutting edges, and each side is ground back to give " relief " of ground back to give " relief " of about 12 degrees to each about 12 degrees to each cutting edge as shown in figure. cutting edge as shown in figure.

Drill Features Drill Features

It is very important that drill It is very important that drill points are central and that points are central and that the lip angles are equal and the lip angles are equal and that the cutting edges are that the cutting edges are unchipped and the clearance unchipped and the clearance angle correct. angle correct.

Drill Features Drill Features

Cutting Speeds. .Material Cutting Speed

Mild steel 18 to 25

stainless steel 12 to18

aluminium Up to 300

Special Type of Drill Special Type of Drill Counterbore DrillCounterbore Drill To form a To form a

flat, or cylindrical recess to flat, or cylindrical recess to accommodate the head of the accommodate the head of the bolt. It is also used to provide a bolt. It is also used to provide a level base on the rough level base on the rough surfaces for nuts and washers. surfaces for nuts and washers.

Counterbore DrillCounterbore Drill

Countersink Drill.Countersink Drill.Countersink Drill To form a conical Countersink Drill To form a conical

shaped recess to enable a shaped recess to enable a countersunk screw or bolt to fit countersunk screw or bolt to fit flush with the surface of the work. flush with the surface of the work.

Reamers Reamers Reamer is made of Reamer is made of hardened High Carbon hardened High Carbon Steel or High Speed Steel. Steel or High Speed Steel. It is classified into hand It is classified into hand reamer and machine reamer and machine reamer. reamer.

Functions of reamerFunctions of reamerFunctions of reamer are Functions of reamer are to control the diameter of a hole to control the diameter of a hole to improve the internal surface to improve the internal surface

finish finish to improve the roundness of the to improve the roundness of the

hole hole

Hand reamerHand reamerHand reamer has two types of Hand reamer has two types of

flutes: - straight and spiral flutes: - straight and spiral flutes. The spiral flutes hand flutes. The spiral flutes hand reamer has a left hand spiral reamer has a left hand spiral flutes. The purpose of the flutes. The purpose of the design is to prevent the reamer design is to prevent the reamer "screw in" the hole. "screw in" the hole.

Hand reamerHand reamer

Machine reamerMachine reamerMachine reamer has a Machine reamer has a

straight shank or taper shank straight shank or taper shank (Morse taper). The taper (Morse taper). The taper shank can fit directly into the shank can fit directly into the spindle of a machine while spindle of a machine while the straight shank is hold by the straight shank is hold by the collet. the collet.

Machine reamerMachine reamer

Expanding Expanding Reamer/Adjustable Reamer/Adjustable

Reamer.Reamer.The cutting diameter can be The cutting diameter can be

slightly varied by adjusting an slightly varied by adjusting an inner taper against the loss cutting inner taper against the loss cutting blades as shown in figure. This blades as shown in figure. This type is used primarily for repetitive type is used primarily for repetitive work to maintain a consistent size work to maintain a consistent size throughout. throughout.

Expanding Expanding Reamer/Adjustable Reamer/Adjustable

ReamerReamer

DrillingDrilling