CONTENTS 1. Cutting tools and cutting materials 1.1 cutting tools- various types of single point cutting tools and their uses, single point cutting too geometry, tool signature and its effect, heat produced during cutting and its effect, cutting speed, feed and depth of cut and their effect 1.2 materials- properties of cutting tool material, study of various cutting tool materials viz. high-speed steel, , cobalt steel cemented carbides, satellite, ceramics and diamond

CUTTING TOOLS AND CUTTING MATERIALS 1.1 INTRODUCTION Cutting material are shaped with the help of cutting tool into usable forms through various processes. The work pieces of most different shapes and sizes and of different materials are worked. 1.2 CUTTING TOOLS The tools which are used for the purpose of cutting the metals in the desired shape and size are called cutting tools. 1.2.1 Classification of cutting tools: Cutting tools are classified into groups. 1. Single point cutting tool. 2. Multi point cutting tool. 1.2.2 Various types of single point cutting tools: Tools for lathe machines On a lathe machine to perform different operations different tools are required. i. Turning tool ii. Facing tool iii. Chamfering tool iv. External threading tool v. Internal threading tool vi. Boring tool vii. Grooving tool, etc.

Tool for planer The planer tools are made of high speed steel. tipped tools are also used. The shape of the tool depends on the type of operation to be performed. Different single point cutting tools are given below: i. Straight and bent roughing tools ii. Straight, roundness and goose neck tools.

1.2.3 Single point cutting tool Geometry Cutting tool geometry concerns with basic tool angles i.e. angles ground on tool to make it efficient in cutting.

Parts of a single point cutting tool The different parts of a single point cutting tool are as follow: 1. Shank 2. Face 3. Flank 4. Heel 5. Base 6. Nose 7. Point. Principal angles of a single point cutting tool The different angles provided on a single point cutting tool have a great signification role to play in successful and efficient machining of different metals.

1. Back rake angle 2. Front clearance angle 3. Side rake angle 4. Side clearance angle 5. Side cutting edge angle 6. End cutting edge angle 7. Nose radius 1.2.4 Tool signature: The term ‘tool signature’ is used to denote a standardised system of specifying the principal tool angles of a single point cutting tool. The seven elements that comprise the signature of a single point cutting tool are always staed in the following order: i. Back rake angle ii. Side rake angle iii. End relief angle iv. Side relief angle v. End cutting edge angle vi. Side cutting edge angle vii. Nose radius. 1.2.5 Heat produced during cutting Considerable heat during machining process is generated at the cutting edge of the tool due to friction between tool and work and the plastic shearing of the metal in the form of chips when the tool is machining metal on a machine tool.

The three different zones are named as follow: 1. Zone A is the shear zone 2. Zone B is the friction zone 3. Zone C is the work-tool contact zone 1.2.6 Cutting speed, feed and depth of cut Cutting speed: The cutting speed of the cutting tool is defined as the speed at which the cutting edge passes over the material and it is expressed in meter per minute. Feed: The feed of a cutting tool is defined as the distance the tool advances into or along the work piece each time the tool point passes a certain position in its travel over the surface. Depth of cut: The depth of cut is defined as the perpendicular distance measured from the machined surface to the under cut surface of the work piece. 1.3 CUTTING TOOL MATERIALS With a great variety of machines and machining operations in use, there is no single tool material, which fulfils all the factors encountered during machining process. The relative importance of each item shifts with the nature of product machined. 1.3.1 Properties of cutting tool material i. It should be easily available. ii. It should have the ability to resist shock called toughness. iii. It should be harder than the material of work piece. iv. IT should have ability to retain its hardness at high temperatures called hot hardness. v. It should be cheap. vi. IT should be able to be fabricated and shaped easily. 1.3.2 Study of various cutting tool materials The following materials are commonly used for manufacturing of the cutting tools. i. High sped steel ii. Tungsten carbide iii. Cobalt steel iv. Cemented carbides v. Stellite vi. Cemented oxides or ceramics vii. Diamond.

CONTENTS 2. Drilling 2.1 Principle of drilling 2.2 Classification of drilling machines and their description.

2.3 Various operation performed on drilling machine – drilling, spot facing, reaming, boring, counter sinking, hole, milling, tapping. 2.4 during drilling, impact of these parameters on drilling, machining time. 2.5 Types of drills and their features, nomenclature of a drill. 2.6 Drill holding devices. 2.7 Types of reamers.

DRILLING INTRODUCTION Drilling is a metal cutting process performed by a rotating cutting tool to make a circular hole in solid materials. The cutting tool is named as a twist drill, since it has sharp twisted edges formed around a cylindrical tool provided with a helical groove along its length to allow the cut material to escape through it during drilling. 2.1 PRINCIPAL OF DRILLING It is defined as to generate a hole by the rotating edge of a cutting tool and exerting a large force on the work piece clamped on the table. 2.2 CLASSIFICATION OF DRILLING MACHINE There is a wide variety of drilling machines. These are manufactured in various sizes to suit the different types of work. They are either hand operated or power driven. The different types of drilling machines are classified as giver below. i. Portable drilling machine: As the name implies, portable drilling machine is a small drilling machine which can be easily carried to work piece or any where in the workshop. It is used for drilling holes in any position which cannot be performed with a standard drilling machine. The portable drilling machines are operated either by hand or power. Depending upon the source of power i.e. manual, electric or pneumatic the machines are of different types which are given below. a. Hand brace, b. Breast drill and c. Electric or Pneumatic drilling machine. ii. Sensitive or bench drilling machine: This drill machine is used for light work. It is usually fitted on a bench so it is called bench drilling machine as shown in fig.

iii. Upright drilling machine: The upright pillar drilling machine is shown in fig. It is designed for handling medium sized work pieces. The constructional feature are very close to a sensitive drilling machine for having a vertical column mounted on the base with a difference that it is larger and heavier than a sensitive drill and is supplied with power feed arrangement.

The upright drilling machine is of two general classes: a. Round column section or pillar drilling machine. b. Box column section. iv. Radial drilling machine: The radial drilling machine is shown in figure. It is intended for drilling medium to large and heavy work pieces. With the use of this machine, the tool is moved to the desired position instead of moving the work for drilling. The machine has a base on which a cylindrical vertical column is mounted. The column carries a radial arm which is raised or lowered by a separate motor and locked at a desired height with the help of clamping levers. v. Multiple drilling machine: this drilling machine is provided with many spindles or drill heads. These may vary from four to twelve or mare. All are driven from one spindle drive gear in one head fitted with one motor so that at a time four, six, eight or twelve holes can be drilled, reamed or tapped. This drilling machine is also named as cluster drilling machine. vi. Gang drilling machine: The gang drilling machine as shown in figure is a type of multiple spindle drilling machine in which the spindles are arranged in a row. These spindles are driven either separately. In this machine a number of operations like drilling, reaming , counter boring and tapping, etc.

vii. Deep hole drilling machine: The deep hole drilling machine used where very long holes of relatively smaller diameter are required to be drilled as in refle barrels, long spindles, crank shafts and long shafts etc. The machine is operated at high speed with low feed. While drilling sufficient quantity of lubricant is pumped to the cutting points for removal of chips and cooling the cutting edges of the drill. For long jobs several supports are provided to prevent deflection. viii. Automatic drilling machine: It is used to perform a series of machining operations at successive units and to transfer the work from one unit to the other automatically. When the work is loaded at the first machine agter finish it moves to the other where different operations can be performed and the finished product comes out from the last unit. 2.3 VARIOUS OPERATIONS PERFORMED ON DRILLING MACHINE 1. Drilling 2. Spot facing 3. Reaming 4. Boring 5. Counter boring 6. Counter sinking 7. Hole milling 8. Tapping. etc. 2.4 SPEED, FEED AND DEPTH OF CUT DURING DRILLING Speed: The cutting speed in a drilling operation is defined as the peripheral speed of a point on the surface of the drill in contact with the work. It is expressed in meters per minute represented by V. Feed: The feed of a drill is defined as the distance a drill moves parallel t its axis, into the work in each revolution of the spindle. It is expressed in mm per revolution represented by Sm. Depth of cut: IN drilling operation, the depth of cut is measured at right angles to the axis of the drill i.e. the direction of feed and is equal to on e half of the drill diameter. It is expressed in mm and represented by t. 2.5 TYPES OF DRILLS Drill: A drill is a flutted cutting tool used to originate or enlarge a hole in a solid material. Drills are manufactured in a wide variety of types and sizes. The types of the drill commonly used are: i. Flat or spade drill ii. Straight fluted drill iii. Twist drill or Two-lip twist drill a. Parallel shank or jobbers twist b. Parallel shank stub series twist drill c. Parallel shank long series twist drill iv. Taper shank core drill v. Oil tube drill vi. Centre drill vii. Special drill 2.6 NOMENCLATURE OF A DRILL The following are the nomenclature, definitions and functions of the different parts of a drill:

Twist drill elements: The following are the twist drill elements. Twist drill is a cutting tool comprised of cutting point at tip of a shaft with helical cutting edge. The various elements of twisting drills are described below.

Axis: An imaginary centre line

Body: It is the main parts of the tool, it extend from the drill shank to the tip of tool.

Shank: It is the cylindrical portion of the drill that held in holding device. The shank may be straight or tapered. Hex shank drill bits are also available. The parallel shanks are provided in small tool bits. It is held in the machine by chucks. The larger size drills are provided tapered shank. It carries a tang at the end of the shank to ensure proper grip between the and driving machine.

Tang: It is the flattened end of the tapered shank, which fit into the driving slot in a socket. It ensures the positive drive from the drill spindle.

Neck: The portion of reduced diameter in between the body and shank

Margin: The part of the body which do not cut away. This narrow extension through the entire body provides clearance between drill and work material. A double margin drill bit have two margin instead of one.

Dead centre or chisel edge: It is the point where two cutting edge meets at the extreme tip. It should always be lie in the axis of twist drill.

Flutes: It is the grooves in twist drill, which provides lip or cutting edge.

Flank: surface of drill, which extends behind the lip to the flute.

Lip: It is the cutting edge formed at the intersection of flank and flute. 2.7 DRILL HOLDING DEVICES The revolving spindle of a drilling machine can hold different cutting tools for different operations. The different methods and devices used to hold drills in drilling machine are: i. Direct fitting ii. Sleeve and socket iii. Collet chuck iv. Drill chuck v. Self centering chuck 2.8 REAMERS A reamer is a type of rotary cutting tool used in metalworking. Precision reamers are designed to enlarge the size of a previously formed hole by a small amount but with a high degree of accuracy to leave smooth sides.

Types of Reamers: i. Hand reamers ii. Machine reamers iii. Adjustable reamers iv. Expansion reamers v. Taper reamers vi. Taper pin reamers vii. Shell reamers 2.9 SAFETY PRECAUTIONS IN DRILLING AND IN REAMING

1. The work should not be held by hand in any case.

2. Proper work holding device should be used to hold the If the work is not held properly, the work tends to rotate along with the drill causing damage to the operator, the machine tool and the cutting tool.

3. The shank of the drill should be cleaned before it is fitted into the The dirt on the shank may make the drill not to have a proper fit into the spindle. This will lead to breakage of drill.

4. The taper hole of the spindle should also be cleaned.

5. The shank of the drill should conform with the spindle hole.

6. Cutting speed and feed should be selected according to the prescribed range.

7. Care should be taken to ensure whether the belt and gears are connected properly.

8. Proper safety plates should be installed around rotating parts like belt drive and gears.

9. The operator should wear safety goggles while operating the drilling machine.

10. The machine should be disconnected from electric terminals when repairs are In general, we should ensure the proper functioning of the machine tool.

CONTENTS 3. Lathe

3.1 Principle of turning 3.2 Description and function of various parts of a lathe 3.3 Classification and specification of various types of lathe 3.4 Drives and transmission 3.5 Work holding devices 3.6 Lathe tools: Parameters/Nomenclature and applications 3.7 Lathe operations:- Plain and step turning, parting off, taper turning, eccentric turning, drilling, teaming, boring, threading and knurling, form turning, spinning. 3.8 Cutting parameters - Speed, feed and depth of cut for various materials and for various operations, machining time. 3.9 Speed ratio, preferred numbers of speed selection. 3.10 Lathe accessories:- Centers, dogs, different types of chucks, collets, face plate, angle plate, mandrel, steady rest, follower rest, taper turning attachment, tool post grinder, milling attachment, Quick change device for tools. 3.11 Brief description of capstan and turret lathe, comparison of capstan/Turret lathe, work holding and tool guiding devices in capstan and turret lathe.

LATHE INTRODUCTION The history of invention of lathe dates back to eighteenth century. The first useful form of lathe wit essential features, was made by Henry Maudslay, a Britisher in the year 1797. Later on as years passed, developments and researches led to a number of amendments and the result is what we see today. Actually lathe was the first machine tool which came into existence as a useful machine for metal cutting. Thus it formed the basis of production of all other machine tools which are the result of later developments. 3.1 PRINCIPLE OF TURNING Turning in a lathe is to remove excess material from the work piece to produce a cone-shaped or a cylindrical surface. The work is held between centres during turning operation.

3.2 CLASSIFICATION AND SPECIFICATION OF VARIOUS TYPES OF LATHE The various types of lathe according to their design, construction and use are broadly classified as follows. 1. Speed lathe a. Wood working b. Centering c. Polishing d. Spinning 2. Engine lathe or centre lathe a. Belt drive b. Individual motor drive c. Gear head lathe 3. Bench lathe 4. Tool room lathe 5. Capstan and turret lathe 6. Special purpose lathe a. Wheel lathe b. Gap bed lathe c. T-lathe d. Duplicating lathe e. Missile lathe 7. Automatic lathe 3.3 DESCRIPTION AND FUNCTION OF VARIOUS PARTS OF A LATHE Figure illustrates the various parts of a centre lathe. Following are the principal parts. 1. Bed 2. Head stock 3. Tail stock 4. Carriage 5. Feed mechanism 6. Screw or thread cutting mechanism

 Headstock: The headstock is fixed on the machine and it consists of many pulleys,

lever, spindle, chuck, and gear box.

 Spindle: The spindle is in the head box which rotates a shaft which is connected to the chuck. This chuck holds a work piece, so the work pieces also rotate.

 Gear box :The gear box is in the head stock which rotates the chuck at different speeds.

 Chuck: Chuck is used for mounting of metal pieces which are not round shape while having a triangular or square shape.

 Tailstock: The tailstock is a moveable part and could be locked. It consists of a barrel that can move forward and backward. Barrel consists of a Dead Centre which is used to support a work piece.

 Carriage: The carriage is also a movable part which moves on bed ways. It moves on left and right. It consists of the saddle, cross slide, compound rest, top slide or tool post and the apron. It is used as mounting and for the position of tool post.

 Saddle: The saddle has H shaped. It is on the carriage which helps cross slide to move back and forth on the machine.

 Cross slide: Cross slide is on the carriage and moves on the saddle. It moves back and forth to give depth of cut to the metal specimen by using hand wheel.

 Compound rest: Compound slide is on the cross slide which can rotate. It gives support to tool post. It is used in taper turning by giving an angle.

 Tool post: Tool post is on the compound rest and used to clamp the cutting tool.  Apron: The apron is on the front of the saddle which has hand wheel and levers. It is used to control the movement of carriage on the bed.

 Bed: The bed is the main part of the machine which is fixed. It gives support to all parts of machine like Head stock, Tail stock, Carriage etc.

 Way: Way is machined on bed which is actually the rail and provide the movement to tailstock and carriage.

 Lead screw: It is a long threaded rod on the bed which provides an automatic feed to carriage from head stock to tail stock. It is used for giving threads to the work piece.

3.4 WORK HOLDING DEVICES

The work holding devices are used to hold and rotate the workpieces along with the spindle. Different work holding devices are used according to the shape, length, diameter and weight of the work piece and the location of turning on the work. They are

1. Chucks 2. Face plate 3. Driving plate 4. Carriers 5. Mandrels 6. Centres 7. Rests

1. Chucks

Work pieces of short length, large diameter and irregular shapes, which can not be mounted between centres, are held quickly and rigidly in chuck.There are different types of chucks namely, Three jaw universal chuck, Four jaw independent chuck, Magnetic chuck, Collet chuck and Combination chuck.

Three Jaw self-centering chuck

The three jaws fitted in the three slots may be made to slide at the same time by an equal amount by rotating any one of the three pinions by a chuck key. This type of chuck is suitable for holding and rotating regular shaped work pieces like round or hexagonal rods about the axis of the lathe. Work pieces of irregular shapes cannot be held by this chuck. The work is held quickly and easily as the three jaws move at the same time.

Four Jaw Independent Chuck

There are four jaws in this chuck. Each jaw is moved independently by rotating a screw with the help of a chuck key. A particular jaw may be moved according to the shape of the work. Hence this type of chuck can hold woks of irregular shapes. But it requires more time to set the work aligned with the lathe axis. Experienced turners can set the work about the axis quickly. Concentric circles are inscribed on the face of the chuck to enable quick centering of the workpiece.

Magnetic Chuck

The holding power of this chuck is obtained by the magnetic flux radiating from the electromagnet placed inside the chuck. Magnets are adjusted inside the chuck to hold or release the work. Work pieces made of magnetic material only are held in this chuck. Very small, thin and light works which can not be held in a or- dinary chuck are held in this chuck.

Collet Chuck

Collet chuck has a cylindrical bushing known as collet. It is made of spring steel and has slots cut lengthwise on its circumference. So, it holds the work with more grip. Collet chucks are used in capstan lathes and automatic lathes for holding bar stock in pro- duction work.

2. Face plate

Faceplate is used to hold large, heavy and irregular shaped workpieces which can not be conveniently held between centres. It is a circular disc bored out and threaded to fit to the nose of the lathe spindle. It is provided with radial plain and ‘T’ – slots for holding the work by bolts and clamps.

3. Driving Plate The driving plate is used to drive a workpiece when it is held between centres. It is a circular disc screwed to the nose of the lathe spindle. It is provided with small bolts or pins on its face. Workpieces fitted inside straight tail carriers are held and rotated by driving plates.

Catch Plate

When a workpiece is held between centres, the catch plate is used to drive it. It is a circular disc bored and threaded at the centre. Catch plates are designed with ‘U’ – slots or elliptical slots to receive the bent tail of the carrier. Positive drive between the lathe spindle and the workpiece is effected when the workpiece fitted with the carrier fits into the slot of the catch plate.

4. Carrier

When a workpiece is held and machined between centres, carriers are useful in trans- mitting the driving force of the spindle to the work by means of driving plates and catch plates. The work is held inside the eye of the carrier and tightened by a screw. Carriers are of two types and they are :

1. Straight tail carrier 2. Bent tail carrier

Straight tail carrier is used to drive the work by means of the pin provided in the driving plate. The tail of the bent tail carrier fits into the slot of the catch plate to drive the work.

5. Mandrel

A previously drilled or bored workpiece is held on a mandrel to be driven in a lathe and machined. There are centre holes provided on both faces of the mandrel. The live centre and the dead centre fit into the centre holes. A carrier is attached at the left side of the mandrel. The mandrel gets the drive either through a catch plate or a driving plate. The workpiece rotates along with the mandrel. There are several types of mandrels and they are:

1. Plain mandrel 2. Collar mandrel 3. Step mandrel 4. Cone mandrel 5. Gang mandrel 6. Expansion mandrel

Plain mandrel

The body of the plain mandrel is slightly tapered to provide proper gripping of the workpiece. The taper will be around 1 to 2mm for a length of 100mm. It is also known as solid mandrel. It is the type mostly commonly used and has wide application.

Gang Mandrel

It has a fixed collar at one end and a movable collar at the threaded end. This man- drel is used to hold a set of hollow workpieces between the two collars by tightening the nut. Screwed Mandrel

It is threaded at one end and a collar is attached to it. Workpieces having internal threads are screwed on to it against the collar for machining.

Cone Mandrel

It consists of a solid cone attached to one end of the body and a sliding cone, which can be adjusted by turning a nut at the threaded end. This type is suitable for driving workpieces having different hole diameters.

6. Centres

Centres are useful in holding the work in a lathe between centres. The shank of a centre has Morse taper on it and the face is conical in shape. There are two types of centres namely

 Live centre  Dead centre

The live centre is fitted on the headstock spindle and rotates with the work. The centre fitted on the tailstock spindle is called dead centre. It is useful in supporting the other end of the work. Centres are made of high carbon steel and hardened and then tempered. So the tip of the centres are wear resistant. Different types of centres are available according to the shape of the work and the operation to be performed. They are

i. Ball centre ii. Ordinary centre iii. Half centre iv. Tipped centre v. Pipe centre vi. Revolving centre vii. Inserted type centre

7. Rests

A rest is a mechanical device to support a long slender workpiece when it is turned between centres or by a chuck. It is placed at some intermediate point to prevent the workpiece from bending due to its own weight and vibrations setup due to the cutting force. There are two different types of rests

 Follower rest  Steady rest

Steady rest

Steady rest is made of cast iron. It may be made to slide on the lathe bedways and clamped at any desired po- sition where the workpiece needs sup- port. It has three jaws. These jaws can be adjusted according to the diameter of the work. Machining is done upon the distance starting from the headstock to the point of support of the rest. One or more steady rests may be used to sup- port the free end of a long work. Follower rest

It consists of a ‘C’ like casting having two adjustable jaws to support the workpiece. The rest is bolted to the back end of the carriage. During machining, it supports the work and moves with the carriage. So, it follows the tool to give continuous support to the work to be able to machine along the entire length of the work.

3.5 LATHE TOOLS AND OPERATIONS

The lathe tools parameters nomenclature means a systematic naming of the various parts and angles of a cutting tool. The surface on the point of a tool has a fixed relation to each other which are defined by angles. The principles of single point and multi point cutting tool angles including grinding wheel are the same.

1. Shank: The shank is the portion of the4 which is not ground to form the cutting edge and it is rectangular in cross section. 2. Face: The face of the cutting tool is the surface against which the chip slides upward. 3. Flank: The flank of a cutting tool is the surface which faces the work piece.

4. Heel: The heel of a single point tool is the lowest portion of the side cutting edge. 5. Nose: The nose of the tool is the conjunction of the side and end cutting edges. 6. Base: The base of the tool is the underside of the shank. 7. Rake: The rake is the slope of the top away from the cutting edge. 8. Back rake: the back rake is the plane which forms the face or top of the tool when ground back at a n angle sloping from the nose. 9. Side rake: The side rake shown that the plane which forms the face or to p of a tool when ground back at an angle sloping from the side cutting edge. 10. Side clearance or side relief: This is shows the plane that forms the flank the flank or side or a tool ground back at an angle sloping down from the side cutting edge.

Lathe Operations: 1. Plain and step turning 2. Facing 3. Parting off 4. Taper turning 5. Eccentric turning 6. Drilling 7. Reaming 8. Broking 9. Threading 10. Knurling 11. Form turning 12. Spinning

3.6 CUTTING PARAMETERS

In metal working work pieces of different shapes and dimensions and of different materials ar worked. The different working processes are grouped into cutting and non-cutting. The cutting process by which finished surface of desired shape and dimension is obtained by separating a layer from the parent work piece in the form of chip.

Speed: The speed of the cutting tool is defined as the rate at which its cutting edge passes over the surface of the work piece in unit time. It is expressed in terms of surface sped in meters per minute.

Feed: The feed of the cutting tool is defined as the distance it travels along or into the work piece for each pass of its point through a particular position in unit time. It is expressed in millimetres per revolution.

Depth of cut : The depth of cut ‘t’ is the perpendicular distance measured from the machined surface to the un-cut surface of the work piece. In a lathe the depth of cut expressed as follows:

Depth of cut ‘t’ = D-d/2 mm

Where, D = original diameter of the work surface before machining in mm.

d = Diameter of the machined surface in mm.