met 103 lathe module 4

safety regulations which should be observed when operating a lathe.p g

• Always wear approved glasses.

• Never attempt to run a lathe until you are familiar with its operation• Never attempt to run a lathe until you are familiar with its operation.

• Never wear loose clothing, rings or watches when operating a lathe.

• Remove the chuck key before starting the spindle.

• Always stop the lathe before taking measurements of any kind.

• Always use a brush to remove chips.

• Before mounting or removing accessories, always shut of the power supply to the motor.

• Do not take heavy cuts on long lender piece.

• Do not lean on the machine.MET

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L ENGINEER ING TECHNOLOGY

TYPES OF LATHE

1. ENGINE LATHE

2 . MANUFACTURING 3 . PRODUCTION LATHE

LATHE LATHE

1. BENCH LATHE1 TURRET LATHE2. SPEED LATHE

3. TOOL ROOM / PRECISION LATHE

4 GAP BED LATHE

1. TURRET LATHE

2. SINGLE SPLINDLE A.L

3. NC LATHES4. GAP BED LATHE 3. NC LATHES

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TYPES OF LATHE1 E i l th1. Engine lathes, 2 Manufacturing lathes, 3. Production lathes.

:. Engine Lathes1 (a) Bench lathe

(b) Speed lathe(b) Speed lathe

(c) Precision lathe / Tool room lathe

(d) Gap bed lathe

BENCH LATHE :# A small lathe mounted on bench

# Small in size

# Used for light machining on small work pieces.MET

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SPEED LATHE# C b t d b h bi t# Can be mounted on a bench or cabinet.

# The fast setup , ease of operation, & low main-tenance.

# Used for light machining operations, turning, polishing, & finishing on g g p , g, p g, gsmall precision work.

TOOL ROOM LATHE# Is equipped with special attachments and accessories to allow a variety

of precision operations to be performed.

# It is generally used to produce tools and gauges which are used in tool# It is generally used to produce tools and gauges which are used in tool and die work.

GAP BED LATHEGAP BED LATHE# The bed can be removed to increase the maximum work diameter

that can be revolved

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MANUFACTURING LATHE. 2

# Are basically engine lathes which have been modified by the addition of a tracer attach-ment or a digital readout system.

# Tracer lathes are used to duplicate parts which may be too difficult or tl t d th t f l thcostly to produce on other types of lathes.

PRODUCTION LATHES3 PRODUCTION LATHES. 3

# Are generally used when a large number of duplicate parts must be produced.

TYPES OF PRODUCTION LATHES

(a) Turret lathes,(a) Turret lathes, (b) Single-spindle automatic lathes, (c) Numerically controlled lathes.

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TURRET LATHE# Used to produce a large number of duplicate parts which may require

operations such as turning, drilling, boring, reaming, facing, & threading.

# On some turret lathes, as many as 20 different tools can be mounted

# Each tool may be rotated into position quickly and accurately.

# Once the tools have been set, each part is quickly and accurately producedproduced

SINGLE SPINDLE AUTOMATIC LATHE# designed to automatically mass-produce parts which require# designed to automatically mass produce parts which require

primarily turning and facing operations.

# Automatic lathes generally have two tool slides mounted on the carriage. g

# The front-slide tooling is used for turning and boring operations.

# The rear-slide tooling is used for facing, undercutting, chamfering,

and necking operationsMET

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NUMERICALLY CONTROLLED LATHE# One of the latest modifications of the basic engine lathe# One of the latest modifications of the basic engine lathe.

# This lathe, controlled by numerical tape, is used primarily for turning operations and can economically and automatically produce shafts of almost any shapeproduce shafts of almost any shape.

# This lathe can perform most types of lathes and provides saving in tooling, setup, and cycle time

Size of the Engine Lathes

# The size of an engine lathe is determined by the maximum diameter of work which may be revolved over the bed.

# The length of a lathe is stated by the length of the bed.

The size of a lathe is measured by :

1. Length of bed2. Swing, the largest diameter that can be rotated3. Maximum useable distance between centers

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LATHE……………….

# A support for the lathe accessories or the work piece.# A way of holding and revolving the work piece. # A means of holding and moving the cutting tool.

MAIN PARTS OF ENGINE LATHE AND ACCESSORIES

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LATHEPARTS OF ENGINE MAIN 1. BED

2. HEADSTOCK

3. TAILSTOCK

4. CARRIAGE

. BED1

The bed is a heavy ruggedThe bed is a heavy rugged casting made to support the working parts of lathe. BEDBED

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. HEADSTOCK2

The headstock is clamped on the left-hand side of the bed.

The headstock spindle, a hollow cylindrical shaft supported by bearings, provides a drive from the motor to work-holding devices.

Headstock (A gear-drive) MET

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. TAILSTOCK3

The tailstock is made up of two units.

The top half can be adjusted on the base by twoThe top half can be adjusted on the base by two adjusting screws for aligning the dead and live centers for parallel turning.

The tailstock hand wheel moves the tailstock spindle inmoves the tailstock spindle in or out of tailstock casting.

Tail StockMET

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. CARRIAGE4

The carriage supports the cutting tool and used to move it along the bed of the lathe for turning

tioperations.

Main parts of the carriage are1.SADDLE,

2 APRON2.APRON,

3.CROSS-SLIDE

4. TOOLPOST

5. COMPOUND REST

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CUTTING TOOLS ANGLES

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TYPES OF LATHE CUTTING TOOLS# Left and Right-Cut Roughing Tools

# Finishing Tools

# Boring and Inside Threading Tools# Boring and Inside Threading Tools

# Facing Tools

# Round-Nose Turning Tools

# Threading Tool

# Parting Tool

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Tool MaterialsTh h d f t l t b t th th t f th t i l b i hi dThe hardness of a tool must be greater than that of the material being machined.

# Nature of the finished product.# Type of operation# Type of operation.# Volume of production.# Tool design details.# Condition of tool.# Type of material being machined.

CARBON STEEL TOOLSCARBON STEEL TOOLS

# Are characterized by low hot hardness and poor hardenability. # Carbon contents range from 0.8 percent to 1.3 percent. # Tools of this type can be used for light work where temperatures produce do not

exceed 204°C (400°F).

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Alloy Steels-Medium

# These steels are not satisfactory for operations where high temperatures are# These steels are not satisfactory for operations where high temperatures are encountered, as in high production.

# In finishing operations, they can be used successfully

Speed Steels-High Speed SteelsHigh

# Are characterized by superior wear resistance and hot hardness. # It contain up to 18 percent tungsten and 51.5 percent chromium as the

principal alloying elements.# Other alloying elements such as Mo & Co give special qualities. # These cutters will retain keen cutting edges at temperatures up to 593°C .

Cast Alloys

# A number of nonferrous alloys known as stellites have been developed for use as cutting toolsas cutting tools,

# These alloys usually contain 2 to 4 percent carbon, 14 to 29 percent tungsten, 27 to 32 percent chromium, 40 to 50 percent cobalt.

# The tools must be used as cast and cannot be heat-treated.

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Cemented Carbide

# Are known by trade names such as Carboloy® Kenna metal® Vascoloy# Are known by trade names such as Carboloy®, Kenna-metal®, Vascoloy-Ramet®, and Pirthite®.

There are two general grades cemented carbides in use:

(1) The "C" grade is made up of tungsten carbide with cobalt as a binder. This grade is used in machining cast iron and nonferrous metals.

(2) The "S" grade is made up of tungsten titanium and tantalum carbides with(2) The S grade is made up of tungsten, titanium, and tantalum carbides with cobalt as a binder. This grade is used on steels.

# The cobalt content may vary from 3 percent to 16 percent.

Cemented carbides have the following characteristics:

(1) High hardness over a wide range of temperatures.(1) High hardness over a wide range of temperatures.(2) High thermal conductivity(3) Low thermal expansion(4) Stiffness.

# Cemented carbide should be used at much higher operating speeds than high-speed steel tools. MET

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TOOL FAILURE

There are many factors that can contribute to the failure of a cutting tool TheThere are many factors that can contribute to the failure of a cutting tool. The following are a few of these factors:(1) Temperature failure.(2) Fracture of the tool point. (3) Tool wear

Temperature FailureThe heat generated at the cutting edge of the tool may become excessive TheThe heat generated at the cutting edge of the tool may become excessive. The heat will cause the tool to soften. Tool failure will occur. This type of failure occurs quite rapidly after a certain temperature is reached.

Fracture of Tool PointBecause of their hardness, carbide-tipped tools are mechanically brittle and weak. Cutting forces may be too great for a given tool. This will cause small portions of the tip to break away In some instances the whole tip may be destroyed If thethe tip to break away. In some instances, the whole tip may be destroyed. If the tool or work is not properly supported, vibration and chatter may occur. These can cause tool point to fracture.

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Tool Wear

Tool wear can be attributed to two basic causes:Tool wear can be attributed to two basic causes:(1) Wear due to plowing or abrasive action of the carbides or other hard

particles in the work piece.(2) Wear resulting from instantaneous "welds" that occur when the chip and

finished surface slide over the tool face

LATHE TOOLHOLDERS AND TOOLPOSTS

Lathe cutting tools are generally held by two methods:

, which provide a means of rigidly holding the cutting tool. tool holders) In 1(which provide a means of holding either a tool holder or atool posts) In2( , which provide a means of holding either a tool holder or a tool posts) In 2(

cutting tool. The most common are the standard (round), turret, heavy-duty (open-side), and quick-change tool posts

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Holders TypesTool

Following are the tool holders types:Following are the tool holders types:

1. Tool holders for High Speed Steel (HSS) Tool bits2. Tool holders for Brazed Carbide Tipped Tool bits3. Cutting Off Tool holders4. Threading Tool holders5. Boring Tool holders

TypesTool Posts

Following are the tool holders types:

1. Standard (Round) Tool post2. Turret Type Tool post3 Quick-Change Tool post3. Quick Change Tool post

a. Dovetailed tool postb. Boring Bar holder

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WORK HOLDING DEVICES1 With the faceplate1. With the faceplate. 2. With the lathe dog. 3. With the lathe chuck 4. With the collet chuck.4. With the collet chuck.

- This is independent chuck generally has four jaws , which are adjusted individually on the chuck

- For holding cylindricalSt k t d adjusted individually on the chuck

face by means of adjusting screws- Stock centered

Three-Jaw Universal Chuck Four-Jaw Independent Chuck MET

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iece # Work pieces can be bolted to the faceplate.

Wor

kpi

WFaceplatesFaceplatesFaceplatesFaceplates

Collet chuck is used to holdCollet chuck is used to holdCollet chuck is used to hold Collet chuck is used to hold small work piecessmall work pieces

Collet ChuckWork holding devices…. MET

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D ill h k ith t d h k t fit t il t kDrill chuck with a tapered shank to fit tailstock

LATHE DOG

Work holding devices…. MET

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CUTTING SPEED AND FEEDSCUTTING SPEED

Cutting speed for lathe work may be defined as the rate at which a point on the circumference of the work passes the cutting tool in a minute.

Cutting speed may be expressed in feet per minute (ft/min) or meters per minuteCutting speed may be expressed in feet per minute (ft/min) or meters per minute (m/min).

M t i C l l tiInch Calculations

12x)( ftCS

Metric Calculations

320xCS.).(x

12x)(min/indiawork

ftCSr

(mm)D

320xmin/ CSr

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Lathe Feed

The feed of a lathe is define as the distance the cutting tool advances along the length of the work for every revolution of the spindle.

fl hr/minxfeed

cutoflengthCutting Time =

Speed, feed, and depth of cut in turning.MET

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MACHINING OPERATIONS1 FACING1.FACING

2.TURNING

3.BORING

FACING

3.BORING

4.TAPER TURNING

5.CHAMFERING

6.THREADING

7.DRILLING

TURNING

BORING

8.REAMING

9.TAPPING

10.COUNTER SINKING

11.COUNTER BORING

12.PARTING

13.KNURLING MET

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THREADING

TAPPING

TAPER TURNING

THREADING

DRILLING & REAMNINGCSK & C’BORE

KNURLING& PARTING MET

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met 103 lathe module 4

Documents

i ne er

basic engine lathe lathe

production lathe lathe

small lathe

lathe accessories

bed en g

theworking parts of

revolved en g