Mec-202 Term Paper

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Drilling Machines & Their Static and Dynamic

Analysis

Sonu Kumar Singh

Regd.no.10904590

Roll no.RC4912B44

Lovely Professional University

Chaheru, (Punjab)

I. Abstract

This term-paper enlighten us about the drilling machine and its

behavior during static and dynamic position. It also describes the

different types of operation performed on a drilling machine, and

characteristic of the drilling machine.

II. Keywords

III. Introduction to Drilling Machine

The powered drill press was developed by James Nasmyth

around 1846, which permitted drilling of accurate holes in

metal.[1]

Drilling is a machining operation used to create a

round hole in a work-part. This contrast with boring, which

can only be used to enlarge an existing hole. Drilling is

usually performed with a rotating cylindrical tool that has two

cutting edges on its working end. This tool is called a drill bit

or drill. The rotating drill feeds into the stationary work-part to

form a hole whose diameter is equal to the drill diameter.

Drilling is customarily performed on a drill press, although

other machining tools also perform this operation.[2]

Drilling

Machines may be used to perform other operations. They can

perform countersinking, boring, counter-boring, spot facing

reaming, and tapping.[3]

Figure-1 shows a typical figure of a Drilling Machine, in this

figure each & every part is named for more clarification

working of each and every part is described further In this

term paper.



IV. Operations Related to Drilling Machine

Several operations are related to drilling. These are illustrated

in the figure-2 and described in this section. Most of the

Operations follow drilling; a hole must be made first by

drilling, and then the hole is modified by one of the other

operations. Centering and spot facing are exceptions to this

rule. All of the operations use rotating tools.[4]

a) Reaming

Reaming is used to slightly enlarge a hole, to provide a better

tolerance on is diameter, and to improve its surface finish. The

tool is called a reamer, and it usually has straight flutes.[5]

Reaming can be done on a drilling machine by using a hand

reamer or using a machine reamer. When we must drill and

ream a hole, it is best if the setup is not changed. For example,

we should drill the hole (slightly undersized) and then ream

the hole before moving to another hole. This method will

ensure that the reamer is accurately aligned over the hole. If a

previously drilled hole must be reamed, it must be accurately

realigned under the machine spindle. Most hand and machine

reamers have a slight chamfer at the tip to aid in alignment

and starting.[6]

b) Tapping

This operation is performed by a tap and is used to provide

internal screw threads on an existing hole.[7]

Tapping i

accomplished on the drilling machine by selecting and drilling

the tap drill size, then using the drilling machine chuck to hold

and align the tap while it is turned by hand. The drilling

machine is not a tapping machine, so it should not be used to

power tap. To avoid breaking taps, ensure the tap aligns with

the center axis of the hole, keep tap flutes clean to avoid

jamming, and clean chips out of the bottom of the hole before

attempting to tap.[8]

c) Counter-boring

Counter-boring provides a stepped hole, in which a large

diameter follows a smaller diameter partially into the hole. A

counter-bored hole is used to seat bolt heads into a hole so the

head do not protrude above the surface as shown in figure-3.[9]

Counter-bored holes are primarily used to recess socket head

cap screws and similar bolt heads slightly below the surface

Both counter-boring and spot-facing can be accomplished with

standard counter-bore cutters.[10]



d) Counter-sinking

This is similar to counter-boring, except that the step in the

hole is cone-shaped for flat head screws and bolts. [11] In other

words, Countersinking is the tapering or beveling of the end of

a hole with a conical cutter called a machine countersink.

Often a hole is slightly countersunk to guide pins which are to

be driven into the work-piece; but more commonly,

countersinking is used to form recesses for flathead screws. If

we talk about the types of counter-sinking, Machine

countersinks for machining recessed screw heads commonly

have an included angle of 82°. Another common countersink

has an included angle of 60° machining lathe centers. Some

countersinks have a pilot on the tip to guide the countersink

into the recess. Since these pilots are not interchangeable,

these types of countersinks can be used for only one size of

hole and are not practical for field or maintenance shops.[12]

e) Centering

Also called center drilling, this operation drills a starting hole

to accurately establish its location for subsequent drilling. This

tool is also called a center drill.[13]

To start a twist drill into

the work-piece, the point of the drill must be aligned with the

center-punched mark on the work-piece. Some drilling

operations may not require a precise alignment of the drill to

the work, so alignment can be done by lining up the drill by

hand and eye alone. If a greater precision in centering

alignment is required, than more preparation is needed before

starting to drill. The best method to align and start a hole is to

use the combination countersink and drill, known as the center

drill figure-4. Set the drilling machine speed for the diameter

of the tip of the center drill, start the machine, and gently

lower the center drill into contact with the work, using hand

and eye coordination. The revolving center drill will find the

center punched mark on the work-piece and properly align the

hole for drilling. The depth of the center-drilled hole should be

no deeper than two third the length of the tapered portion of

the center drill.[14]

f) Spot Facing

Spot facing is similar to milling. It is used to provide a flat

machined surface on the work-part in a localized area.[15]

We

can also say that Spot facing is basically the same as counter-

boring, using the same tool, speed, feed, and lubricant. The

operation of spot facing is slightly different in that the spot

facing is usually done above a surface or on a curved surface



as shown in figure-5. Rough surfaces, castings, and curved

Surfaces are not at right angles the cutting tool causing great

strain on the pilot and counter-bore which can lead to broken

tools. Care must be taken when starting the spot facing cut to

avoid too much feed. If the tool grabs the work-piece because

of too much feed, the cutter may break or the work-piece may

be damaged. Ensure that the work is securely mounted and

that all backlash is removed from drilling machine spindle.[16]

V. Types of Drilling Machine

Drilling machine is categorized on the different bases like on

the basis of its construction and on the basis of its feed.

a. On the basis of construction

On the basis of its construction it is divided into six types

which are described below with figure, one by one.

i. Portable Drilling Machine.

Hand operated drill is one of the simplest examples of portable

drilling machines. Most portable drill is equipped with small

electric motors by which they can be operated at high speed

Usually they accommodate up to Drill 12mm diameter.[17]

ii. Sensitive Drilling Machine.

The figure-6 shown below is the typical figure for a sensitive

drilling machine. It can perform with different qualities:

• It can Drill a holes from 1.5 to 15mm

• Operator senses the cutting action so sensitive

drilling machine.

• It has Light weight-light duty.

• It is used primarily for low production.

• It is not as much applicable in industry, where mass

production rate is required.



• It has not a great accuracy.

• In this drilling machine, spindle head is fixed with

respect to the base of the drilling machine.

• Only the tables of the drilling machine can move with

respect to the column vertically.[18]

iii. Radial Drilling Machine.

The figure-7 shown below is the typical figure for a radial

drilling machine. It has also different specialties other than the

sensitive drilling machine:

• It is the largest and most versatile used for drilling

medium to large and heavy work pieces.

• Its Drill Head can slide on its radial arm horizontally

• Its radial arm can also slide on the column due to

elevating screws as shown in figure-7.

• It has two different electric motors; on is for giving

rotational motion to the drill, and another motor is for

elevating screw.

• It is capable to do the large work.

• In this type of drilling machine, Work-piece i

stationary.[19]

iv. Up-right Drilling Machine.

A Typical Diagram for The Upright Drilling Machine i

shown below in the figure-8. It has its own specialties and is

an improved version of the previous available drilling

machine:

• It is larger in size than the sensitive Drilling Machine

• It can be equipped with a gearbox and variable speed

head.

• It has both Hand and automatic feed mechanism.

• It has automatic coolant system

• Its table can move on a rack and pinion system

• Drill holes up to 50mm.[20]



v. Gang Drilling Machine.

The typical diagram for a Gang Drilling Machine is shown in

the figure-9. It is a multi-purpose drilling machine.

• It is equipped with more than one spindle.

• It has multi-head arrangement.

• Still, it has single table.

• It is mainly used for production set-up.

• It is able to do multiple operations at one location

(drill, ream, tap, c’sink, c’borte etc.).[21]

vi. Multi-spindle Drilling Machine

The Typical Diagram of a Multi-Spindle Drilling Machine is

shown below in the figure-10. As its name suggest, it has more

than one spindle as shown in the figure.[22]

b. On the basis of feed

On the basis of feed system drilling machine is divided into

two types:

1) Hand Driven Drilling Machine

The hand-feed drilling machines (Figure-11) are the simplest

and most common type of drilling machines in use today.

These are light duty machines that are hand-fed by the

operator, using a feed handle. So that the operator is able to

“feel” the action of the cutting tool as it cuts through the work

piece. These drilling machines can be bench or floor mounted

They are driven by an electric motor that turns a drive belt on

a motor pulley that connects to the spindle pulley. Hand-feed

machines are essentially high-speed machines and are used on

small workplaces that require holes 1/2 inch or smaller

Normally, the head can be moved up and down on the column

by loosening the locking bolts. This allows the drillin

machine to drill different heights of work.[23]



VII. Construction Characteristic of a Drilling Machine

All drilling machines have the following construction

characteristics as shown in Figure-12: a spindle. Sleeve or

quill, Column, head, worktable, and base.

•

The spindle holds the drill or cutting tools andrevolves in a fixed position in a sleeve. In most

drilling machines, the spindle is vertical and the work

is supported on a horizontal table.

• The sleeve or quill assembly does not revolve but

may slide in its bearing in a direction parallel to its

axis. When the sleeve carrying the spindle with a

cutting tool is lowered, the cutting tool is fed into the

work: and when it is moved upward, the cutting tool

is withdrawn from the work. Feed pressure applied to

the sleeve by hand or power causes the revolving drill

to cut its way into the work a few thousandths of an

inch per revolution.

• The column of most drill presses is circular and built

rugged and solid. The column supports the head and

the sleeve or quill assembly.

• The head of the drill press is composed of the sleeve

spindle, electric motor, and feed mechanism. Thehead is bolted to the column.

• The worktable is supported on an arm mounted to the

column. The worktable can be adjusted vertically to

accommodate different heights of work. or it may be

swung completely out of the way. It may be tilted up

to 90° in either direction, to allow for long pieces to

be end or angled drilled.

• The base of the drilling machine supports the entire

machine and when bolted to the floor, provides for

vibration-free operation and best machining

accuracy. The top of the base is similar to a

worktable and maybe equipped with T-slots fo

mounting work too large for the table.[26]

VIII. Drill Nomenclature

Drill is composed of three principle parts namely Point

Shank & Body. We will Discuss All of these along with

its sub-component. For all of this we refer the figure-14

a) Point

The point is the cone shaped end and does the cutting. I

consists of the following:

• Dead Centre: it is the sharp edge at the extreme tip o

the drill. This should always be in the exact center of

the drill axis.

• Lips: These are cutting edges of the drill.

• Heel : It is the portion of the point back from the lips

of cutting edge.



• Lip Clearance: It is the amount by which the surface

of the point is relieved back from the lips.[27]

b) Shank

Portion of drill which is damped in the spindle. Shanks are

two types, may be straight or tapered. Straight shank drills are

of two types may be straight or tapered. Straight shank drills

are used with a chuck. Tapered shanks have self-holding

tapers. At the end of tapered end shank there is the long. This

fits into the slot in the spindle. Tong also offers a means of

separating the taper from the holding device.[28]

c. Body

Portion between shank and point is called the body of the drill.

• Flutes: Flutes are two or more spiral (or parallel)

grooves that run the length of the drill body. It curls

the chip tightly. These are the channels through

which the chip escapes from the hole being drilled.

Lubricant and coolent get down to the cutting edge.

• Margin: It is the narrow strip extending back the

entire length of the flute. It is full diameter of the

drill.

• Body Clearance: it is reduced to cut down the friction

between the drill and wall of hole.

• Wele: it is the metal column that separates the flutes

It gradually increases in thickness towards the shank

to give added strength.[29]

d. Others

• Rake Angle: The angle between the flute and the axis

of the drill that forms the cutting edge is known asthe rake angle as shown in the figure-8d. Generally

the rake angle is between 180 and 450, with 30°

being the most common. Drills used on armor plate

or other very hard materials need a reduced rake

angle to increase the support behind the cutting edge

Soft materials, like brass and bronze, also use a

reduced rake angle to prevent the drill from grabbing

The rake angle partially governs the tightness with

which the chips curl and the amount of space they

occupy. If the rake angle is too small, the lips may be

too thin and break under the strain of drilling. Too

large of a rake angle makes the drill chatter and

vibrate excessively.[30]



IX. Cutting Condition in drilling

The cutting speed in a drilling operation is the surface speed at

the outside diameter of the drill. It is specified in this way for

convenience, even though nearly all of the cutting is

accurately performed at lower speeds closer to the axis of

rotation. To set the desired cutting speed in drilling, it is

necessary to determine the rotational speed of the drill for its

diameter. Let N represents the spindle ,

Where = cutting speed, and D = the

drill diameter, mm (in). In some drilling operations, the work

piece is rotated about a stationary tool, but the same formula

applies.

Feed in drilling is specified in

Recommended feeds are roughly proportional to drill

diameter; higher feeds are used with larger diameter drills.

Since there are (usually) two cutting edges at the drill point,

the uncut chip thickness (chip load) taken by each cutting edge

is half the feed. Feed can be converted to feed rate using the

same equation as for turning operation:

Where, .

Drilled holes are either through holes or blind holes or blind

holes, figure-15 & figure-16 shows the through holes or blind

holes respectively. In through holes, the drill exists the

opposite side of the work; in blind holes, it does not. The

machining time required to drill a through hole can be

determined by the following formulae;

Where, = work

thickness, mm (in); and = an approach allowance tha

accounts for the drill point angle, representing the distance the

drill must feed into the work before reaching full diameter, as

shown in figure-15; this allowance is given by

Where Drill point angle.



b) Carbide-Tipped drills

Most of the tool materials have the limitations, such as they

cannot be used as effectively where high cutting speeds, and

hence high temperatures, are invoked, and their tool life can

be relatively short. Carbides, also known as cemented or

sintered carbides, were introduced in the 1930s to meet the

challenge of higher machining speeds for higher production

rates.

Because of their high hardness over a wide range of

temperatures, high elastic modulus and thermal conductivity,

and low thermal expansion, carbides are among the most

important, versatile, and cost effective tool and die materials

for a wide range of applications. However, stiffness of themachine tool is important and light feeds, low cutting speeds,

and chatter can be determined, that’s why this material is used

as drill.

The two basic groups of carbides used for Drilling operations

are tungsten carbide and titanium carbide. In order to

differentiate them from coated tools or tipped tools, plain

carbide tools are usually referred to as uncoated carbides.[33]

c) Other materials for Drill

There are still some other options as a drill material which is

listed below.

• Solid Carbide drill.

• TiN coated drills.

• Carbide coated masonry drills.

• Parabolic drills.

• Split point drills.[34]

XI. Drill Holding Device

The revolving vertical spindle of the drilling machine holds

and drives the cutting tool. In order to use various sizes and

shapes of drills in various machines three types of dril

holding devices, which fit the spindle of the drilling machines

are used: the geared drill chuck, the drill sleeve, and the dril

socket as shown in figure-17. The larger drilling machines

have a spindle that has a standard Morse taper at the bottom

end. There are three types of drill holding devices: the geared

drill chuck, the drill sleeve, and the drill socket.[35]

a) Geared Drill Chuck

Drills with straight shanks are held in geared drill chuckswhich have three adjustable jaws to clamp onto the drill

Smaller size drills are made with straight shanks because of

the extra cost of providing these size if tapered. Geared dril

chucks come in various sizes, with the 3/8 or 1/2-inch capacity

chuck being the most common. The shank of the chuck is set

into the spindle of the drilling machine by inserting the

chuck’s shank into the spindle’s internal taper and seating the

shank into the taper with a light blow with a soft hammer.

Both the internal and external taper surfaces must be clean

and free of chips for the shank to seat and lock properly. The



drill is locked into the chuck by using the chuck key to

simultaneously tighten the three chuck jaws. Geared drill

chucks can also come with a Morse tapered shank and may

have a different method of attaching they may screw on, have

a Jarno taper, or a Jacob’s back taper.[36]

b) Drill sleeve & Drill Socket

Morse taper shank drills come in several sizes, thus, adapters

must be used for mounting them into various drilling machine

spindles. Drill sleeves and drill sockets are designed to add to

or subtract from the Morse taper for fitting a drill into the

chuck spindle. For example, it is common for a 3/4 inch twist

drill to have a Morse taper of size #2, #3, or #4. It is also

common for a drilling machine spindle to have a Morse taper

of size #3 or #4, and it can be adapted for many other Morse

taper sizes, depending on the size of the drill.

A drill too small for the machine spindle may be fitted into a

socket or sleeve which has a taper hole of the proper size to

hold the drill and a taper shank of the proper size to fit the drill

spindle. Sometimes, more than one socket or sleeve is needed

to build up the shank to tit into the drilling machine spindle.

Sockets and sleeves may be obtained in a number of different

sizes and hole shank taper combinations. Sockets, sleeves, and

taper shank drills are mounted into the aligning slots of the

spindle and lightly tapped with a soft hammer to seat in place.

[37]

c) Drill Drifts

Drill drifts are flat, tapered keys with one rounded edge that

are designed to fit into a spindle chuck’s slot to force a taperedshank drill loose. The rounded top of the small end of the drill

drift is designed to face upward while inserting the drift into

the slot. There are two types of drill drifts, the standard type

and the safety type as shown in Figure-18. The standard drift

must be inserted into the chuck’s slot and then struck with a

soft hammer to jar the taper shank drill loose. The drill wil

fall quickly if not held by the hand and could break or cause

injury. The safety drill drift has a sliding hammer weight on

the drift itself to allow for a free hand to stay constantly on the

drill as it comes loose.[38]

XII. Work Holding and Drilling Devices

Work holding devices are used to hold the work steady for an

accurate hole to be drilled, and so a safe drilling operation can

be accomplished. Drilling support devices are used to keep the

work-piece above the worktable or vise surface and to keep

the work-piece aligned for drilling. Some devices are fairly

simple and are used for drilling operations that do not require

a perfect hole. Other devices are very intricate and designed

for more accurate drilling. Many work holding devices are

used with one another to produce the most stable work setup

for drilling.

a) Machine Table vises

A machine table vise is equipped with jaws which clamp

against the work-piece, holding it secure. The vise can be

bolted to the drilling table or the tail can be swung around to

lay against the column to hold itself steady. Below are listed



many types of special purpose machine table vises available to

machine operators.

• The standard machine table vise is the simplest of all

vises. It is equipped with two precision ground jaws

for holding onto the work and a lead screw to tighten

the one movable jaw to the work as shown in Figure-

19.

• The swivel vise is a machine vise that has an

adjustable base that can swivel through 360° on a

horizontal plane as shown in Figure-19.

• The angle vise is very similar to the table vise.

Except this vise can be tilted to 90°. To be

perpendicular to the work table as shown in Figure-

19.

• Many other vises are available. They include the

compound vise. Universal vise, magnetic vise, and

contour vise.

b) Step Blocks

These holding devices are built like stairs to allow for height

adjustments in mounting drilling jobs and are used with strap

clamps and long T-slot bolts as shown in figure-20.

c) Clamps

Clamps are small, portable vises or plates which bear agains

the work-piece and holding devices to steady the job. Clamps

are made in numerous shapes to meet various work-holding

needs. Common types of clamps are the C-clamp, the parallel

clamp, the machine strap clamp, the bent-tail machine clamp

the U-clamp, and the finger machine clamp, examples are

shown in the figure-20.

d) V-Blocks

V-blocks are precision made blocks with special slots made to

anchor clamps that hold workplaces. The V-slot of the block is



designed to hold round workplaces. The V-block and clamp

set is usually used to hold and drill round stock

e. Angle Plates

Angle plates are made in a 900 angle with slots and bolt holes

for securing work to the table or to other work holding

devices, examples are shown in the figure-20.

f. T-Slot Bolts

These specially made bolts have a T-shaped head that is

designed to slide into the T-slots of the drilling machine’s

worktable. A heavy duty washer and nut are used with the T-

bolt to secure the work.

g. Jigs

Drill jigs are devices designed for production drilling jobs.

The workplaces are clamped into the jig so that the holes will

be drilled in the same location on each piece. The jig may

guide the drill through a steel bushing to locate the holes

accurately.[39]

XIII. Drilling Support Devices

These devices are important to keep the work-piece parallel

while being supported above the worktable or vise surface and

to keep the drill from cutting into the holding device or

worktable. The following two devices are the most common

used.

• Blocks are used with clamps to aid in securing and

supporting the work. These blocks are usually

precision ground of hard steel for long life.

• Parallels are precision ground rectangular bars are

used to keep the work-piece parallel with the

worktable when the work-piece must be raised above

the worktable surface, such as when drilling

completely through a work-piece as shown in Figure-

21. Parallels come in matched sets and can be solid or

adjustable as needed.[40]

XIV. Cutting Fluids

Cutting fluids, lubricants, and coolants are used in drilling

work to lubricate the chip being formed for easier removal, to

help dissipate the high heat caused by friction, to wash away

the chips, to improve the finish, and to permit greater cutting

speeds for best efficiency. In drilling work, the cutting fluid

can be sprayed, dripped, or machine pumped onto the work

and cutting too! to cool the action and provide for maximum

tool life. Drilling, reaming, and tapping of various materials

can be improved by using the proper cutting fluids. Cutting-fluids can be produced from animal, vegetable, or mineral oils

Some cutting fluids are very versatile and can be used for any

operation, while other cutting fluids are specially designed for

only one particular metal.[41]

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