MET 103 Drilling module-2

SAFETY PRECAUTIONS WHEN WORKING WITH DRILL PRESSESDRILL PRESSES

• Always wear appropriate safety goggles.

• Never leave the chuck key in the drill chuck or the drill drift in the spindle.

• Mount the work securely before drilling. Do not hold thin or small pieces in the hands.

• Remove chips with a brush or piece of wood. Never use the hands.

• Do not attempt to stop the spindle with the hands after turning the machine off.

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L ENG INEER ING TECHNOLOGY

SAFETY PRECAUTIONS WHEN WORKING WITH DRILL PRESSESDRILL PRESSES

• Keep long sleeves, other loose clothing, and especially long hair away from the revolving spindle or beltsaway from the revolving spindle or belts.

• Do not operate the drill with the covers or guards removed.

• Keep the work area and floor clean and free of oil and grease.

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Drilling Machine…Drilling is the operation of producing circular hole in the work-piece by using a rotating cutter called “DRILL”DRILL”.

The machine used for drilling is called drilling machine.The most common drill used is the twist drill.

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TYPES OF DRILL PRESSES

1. Sensitive Drill Presses1. Sensitive Drill Presses

2. Upright Drilling Machines

3. Multiple Spindle Head Machines

4 Th R di l D illi M hi4. The Radial Drilling Machine

5. Gang Drilling Machine5. Gang Drilling Machine

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Sensitive Drilling Machine)1(

• Drill holes from 1.5 to 15mm

• Operator thsenses the

cutting action so sensitiveso sensitive drilling machine

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Right Drilling Machine-Up)2( Right Drilling MachineUp)2(

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Right Drilling Machine-Up

• Similar in design to sensitive type but it is larger & more sturdily built.more sturdily built.

• It has a gear mechanism used to change the i dl d d f dspindle speeds and feeds.

• The machine may have mechanical devise to raise e ac e ay a e ec a ca de se to a seor lower the work table.

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Radial Drilling Machine)3(

It is the largest and most versatileversatile used for drilling

di tmedium to large and heavy workheavy work pieces.

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MULTIPLE SPINDLE HEAD MACHINES)4(

• TWO OR MORE DRILLINGHEADS

• EACH HEAD HAS SEVERAL SPINDLES

• SEVERAL HOLES CAN BE DRILLED AT A TIME.

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(5) Gang Drilling Machines• A SERIES OF SINGLE SPINDLE

DRILLS ARE MOUNTED ON A LONG COMMON TABLELONG COMMON TABLE.

• EACH INDIVIDUAL HEAD MAY BE • EACH INDIVIDUAL HEAD MAY BE FITTED WITH DIFFERENT CUTTING TOOLS SUCH AS TWIST DRILL, A COUNTER SINK, OR A DRILL, A COUNTER SINK, OR A REAMER

• DESIGNED FOR MASS PRODUCTION

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L ENG INEER ING TECHNOLOGY• NO NEED OF CHANGING CUTTING TOOLS.

Twist DrillsM f t d f th i t i lManufactured from three main materials1. Carbon-tool steels2. High-speed steel g p3. Cemented-carbide

TWIST DRILLSOFTYPES

1. General –purpose drill

2. Low-helix drill

3. High-helix drill

4. Core drill

5. Coolant hole drillMET

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L ENG INEER ING TECHNOLOGY6. Straight flute drill

1. General-Purpose Drillp• Has two Helical flutes• Designed to perform well on wide• Designed to perform well on wide

variety of materials, equipment and job conditionsjob conditions

• Can be made to suit different conditions and materials by varyingconditions and materials by varying point angle, speeds and feeds

• Straight-shank drills called general-Straight shank drills called generalpurpose jobbers length drills

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Helix Drill-. Low2

• Developed primarily to drill brass andDeveloped primarily to drill brass and thin materials

• Used to drill shallow holes in some• Used to drill shallow holes in some aluminum and magnesium alloysC l l f hi• Can remove large volume of chips formed by high rates of penetration

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Helix Drills-. High3 g

Designed for drilling deep holes inDesigned for drilling deep holes in aluminum, copper, die-cast material, and other metalsand other metals– Material where chips have tendency to jam

High helix angle (35º to 45º)• High helix angle (35º to 45º)• Wider flutes assist in clearing chips from

hole

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. Core Drill4

• Three or four flutesThree or four flutes• Used to enlarge cored, drilled, or

punched holespunched holes• Produced in sizes from ¼ to 3 in.

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5. Oil Hole Drills

• Have one or two oil holes running fromHave one or two oil holes running from shank to cutting point– Compressed air, oil, or cutting fluid can be p , , g

forced through when deep holes being drilled

C i fl id l d ill' i d• Cutting fluid cools drill's cutting edges and flushes chips out of hole

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Fluted Drills-. Straight6 g

• Recommended for drilling operations onRecommended for drilling operations on soft materials such as brass, bronze, copper and various types of plasticcopper and various types of plastic

• Straight flute prevents drill from drawing itself into material while cuttingitself into material while cutting

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A wide variety of matels1 Genearl purpose

Types of drills & ApplicationsA wide variety of matels1.Genearl-purpose

drillBrass & thin matls2. A low-helix drillShallow holes in Al &Mg alloysDeep holes in low tensile st. matels3. A high-helix drillsuch as Al, Cu, & plasticsTo enlarge drilled ,cored or punched holes

4. A core drillholesScrew-m/c and turret lathe 5. A coolant –hole

drillBrass, sheet-metal work and nonferrous matels

6. A straight flute drill

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Twist Drill Parts3.Point

2. Body

1. Shank

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Twist Drill Parts

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1. Drill Shank1. Drill Shank

shank drills-Straight shank drills-StraightHeld in drill chuckUp to ½ inUp to ½ in. in diameter

Tapered-shank drillsFit into internal taper of drill press spindleTang provided on end to prevent drill from

slippingMET

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. Drill Body2

• Portion of drill between shank and point

y

p• Consists of number of parts for cutting• Flutes

– Two or more helical grooves cut around body of drill

– Form cutting edges, admit cutting fluid, allow chips to escape hole

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. Drill Point3Consists of chisel edge, lips, lip clearance,

d h l

o3

and heel.LipsCutting edges formed by intersection of flutes

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point Angles and Clearances-Drill

• For general-purpose drilling, the drill point should be d t i l d d l f 118° d li lground to an included angle of 118° and lip clearance

should range from 8° to 12°.

• The drill point for hard materials should be ground to an included angle from 135° to 150° and the lip clearance should be from 8° to 10°clearance should be from 8 to 10 .

F d illi ft t i l th d ill i t h ld b• For drilling soft materials, the drill point should be ground to an included angle of 90° and the lip clearance ranging from 15° to 18°.

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Four Systems of Drill Sizes

• FractionalFractional• Number

L tt• Letter• Millimeter (Metric)

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FractionalFractionalRange from 1/64 to 4 in. (steps of 1/64th )

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• NumberNumber– Range from 1 to 97 , .228 in. to .0059 in.

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LetterLetterRange from A to Z (A = .234 in., Z = .413 in.)

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Millimeter (Metric)Millimeter (Metric)Straight-shank standard (0.5 to 20 mm)

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CALCULATING RPM

METRIC INCH

rpm = CS X 320 rpm = CS X 4D D

CS= Cutting speed in meters/mint CS= Cutting speed in feet/mintD= Diameter of Drill in mm D= Diameter of Drill in inch

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SELECTION OF THE PROPER SPEEDS AND FEEDS

1. The kind of material being drilled. Softer materials generally are drilled at higher cutting speeds than harder materials

FEEDS

than harder materials2. The kind of cutting tool material. Carbon-steel drills are

used with cutting speeds which are about one-half g pthose used with high-speed steel drills. Tungsten-carbide drills generally are run at higher speeds and lighter feeds than high-speed steel drillslighter feeds than high-speed steel drills.

3. Whether or not a cutting fluid is used.4 The size and the type of drilling machine used and4. The size and the type of drilling machine used, and

the rigidness of the work setup5. The quality of finish desired in the hole.

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q y

COUNTERSINKING AND COUNTERBORINGCOUNTERBORING

COUNTERSINKING : 1. It is the process of making a cone-shaped opening at

the top of a drilled hole for a flat or an oval head machine screwmachine screw.

2. Countersinks may also be used to remove burrs from the top of a drilled holethe top of a drilled hole.

3. The countersinks or cutting tool used for this operation is available with included angles of 60 and 82°. g

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COUNTERBORING :

1. It is the operation of l i th t fenlarging the top of a

drilled hole to a given depth.

2. The enlarged hole creates2. The enlarged hole creates a square shoulder which will accommodate a bolt or cap screw head or theor cap screw head or the shoulder or a pin.

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… Drilling operations

Operations that can be performed on a p pdrilling machine are

1. Drilling2 Reaming2. Reaming3. Boring4 Counter boring4. Counter boring5. Counter sinking6 T i

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6. Tapping

MET 103 Drilling module-2

Education