Lab Manual

LAB 01

LAYOUT OF MACHINE TOOL LAB

NAMES OF MACHINE TOOL LAB APPARATUS

Center lathe Bench lathe Turret lathe Emco lathe Universal milling machine Tool grinder CNC machine Cylindrical grinder Surface grinding machine Shaper machine Drill press (upright) Pedestal drill press Power hacksaw White board Student chairs

CENTER LATHE

MODEL: CL 305

MANUFACTURER: PECO

SWING: 305 mm

MOTOR CAPACITY: 7.5 HP

It is a basic type of lathe which spins a block of material to perform various operations such as cutting, knurling, drilling, boring, reaming, thread cutting, taper turning etc with tools that are applied to the workpiece to create an object which has symmetry about an axis of rotation.

CONSTRUCTION OF CENTER LATHE

It consists of many parts such as headstock, bed, carriage and tailstock and all other accessories which are listed below.

HEAD STOCK

The headstock houses the main spindle, speed change mechanism and change gears. The headstock is required to be made as robust as possible due to the cutting forces involved, which can distort a lightly build housing and induce vibrations that will transfer through to the workpiece, reducing the quality of the finished workpiece.

SPINDLE

The main spindle is generally hollow to allow long bars to extend through to the work area, this reduces preparation and waste of material. The spindle then runs in precision bearing and is fitted with some means of attaching work holding devices such as chucks.

GEAR BOX

The spindle was directly driven by a dedicated electric motor using gear box. The fully geared head allows the speed selection to be done entirely through the gear box.

BED

The bed is a robust base that connects to the headstock and permits the carriage and tailstock to be aligned parallel with the axis of spindle. This is facilitated by hardened and ground ways.

Types of beds include inverted V beds, flat beds and combination V and flat bed. V and combination beds are used for precision and light duty work while flat beds are used for heavy duty work.

CARRIAGE

Carriage holds the tool bit and moves it longitudinally(turning) or perpendicularly(facing) under the control of operator. Carriage can move manually via the hand wheel or automatically by engaging the feed shaft with the carriage feed mechanism. The hand wheels on carriage and its related slides are usually calibrated both for ease of use and to assist in making reproducible cuts.

Parts of carriage are as follows:

1-SADDLE

The casting that fits onto the top of bed and slides along it is known as saddle. It moves only longitudinally.

2-CROSS SLIDE

It stands a top the saddle of the carriage and has a feed screw that travels perpendicular to the main spindle axis. This permits facing operations to be performed and the depth of cut to be

adjusted. This feed screw can be engaged through a gear train to feed shaft to provide automated power feed movement to cross slide.

3-COMPOUND REST

It is attached on the top of cross slide and supports the cutting tool. It is graduated so that any angle can be set for taper turning but it is mostly used for short tapers.

4-TOOL POST

The cutting tool is mounted in the tool post which is attached to the top of compound rest .

5-APRON

The vertical often flate and rectangular plate fastened to the front of the saddle is known as apron and carries a selection of gears and controls that allow the carriage to be power driven up and down the bed and also engage the screw cutting feed and various powered tool feeds should they be fitted.

TAILSTOCK :-

The tailstock is a tool header directly mounted on the spindle axis opposite to the head stock. It has two main parts

Upper part

Lower part

Upper part motion is very critical. It moves not only longitudinally but also in different directions while lower part of tailstock moves only in longitudinal direction.

TAILSTOCK SPINDLE:-

It does not rotate but does travel longitudinally under the action of hand wheel.

QUILL

Sliding member of tailstock is known as quill which can move outward and inward in which dead center is mounted.

FEED AND LEAD SCREW

The feed screw is a long drive shaft that allows a series of gears to drive the carriage mechanisms. These gears are located in apron of carriage. Both the feed screw and lead screw are driven by either the change gears or an intermediate gear box, known as quick change gear box.

The lead screw will be manufactured to either imperial or metric standards and will require a conversion ratio to be introduced to create threads forms from a different family.

External operations

1-Turning:-

It is a process of reducing diameter of work piece to obtain desird shape, size and accuracy by using a turning tool. It may be

-Straight turning

-Taper turning

For taper turning, four methods are used

-Compound rest method

-Taper turning by a form tool

-Taper turning by setting over tail stock

-Taper turning attachment.

2-Facing:-

It is the process of reducing length of work piece to obtain desired size, shape, and accuracy by using a facing tool.

3- Thread cutting:-

It is a process of making threads on work piece by using a thread cutting tool which moves axially along side of work piece

4- Grooving:-

It is a process of making grooves in work piece by using a turning tool moves radially into side of work piece cutting a grooves equal in width to cutting tool.

Internal operation:-

1-Drilling:

It is a process of making hole in work piece by using twist drill mounted in tail stock.

2- Boring:

It is a process of enlargement of holes by using a boring tool.It is commonly performed after drilling.

3-Reaming:

It is a process of giving smoother internal finish to a hole and to obtain a more accurate diameter. It is also performed after drilling.

BENCH LATHE

Model:-BL115

Manufacture:-PECO

Swing:-

The name bench lathe implies a version of the class of lathe small enough to be mounted on a work piece but still full featured and larger then mini lathe or micro lathe.

Using a bench lathe , different operation, drilling, knurling, cutting etc. can be performed to

create a new object.

Part of bench lathe:-

1-Head Stock:-

On the left hand side of bench lathe,the head stock is located.A head stock is the section of the lathe that holds spinning bearing.

SPINDLE:-

It is located in head stock.It is the main rotating shaft on which the chuck is mounted .It is supported by precision thrust bearings mounted in the head stock casting and is driven by a toothed pulley and belt which runs down to a smaller toothed pulley on the motor.

BED:-

A bench lathe has a bed or horizontal beam that supports the main parts of bench lathe and it is also ued to allow the excess material to fall away from the work surface.

CARRIAGE:-

Bench lathe also has a carriage which holds the tool and moves it longitudinally or perpendicularly to perform the different operations.Parts of Carriage are

1. SADDLE:-

It fits on the top of the bed and it moves carriage only in the longitudinal direction.

2. CROSS SLIDE:-

It is mounted on the top of the saddle of carriage and allows the tool to move towards or away from work piece,changing the depth of the cut.

3. COMPOUND REST:-

It is attached on the top of cross slide and supports the cutting tool.It is graduated to perform the taper turning.

4.TOOL POST:-

The cutting tool is secured in the tool post which is mounted on the top of the compound rest.

5.APRON:-

It is the vertical often flat and rectangular plate fastened to front of saddle and it carries a selection of the gears and controls and the clutches that allow the carriage to be power driven up and down the bed and also engage screw cutting feed and various powered tool feeds.

TAIL STOCK:-

It is rear section of machine that is located to the left of the bed.The purpose of this assembly isto support the other end of the work piece and allow it to rotate.For some turning operations,workpiece is not supported by tail stock so that material can be removed from the end.

LEAD SCREW:-

This is a long threaded rod normally found running along the front of the bed and advances carriage for thread cutting operations.

FEED ROD:-

It is unthreaded rod below the lead screw and it advances carriage for any operations other than threading when automatic feed lever is engaged.

OPERATIONS PERFORMED BY BENCH LATHE:-

Turning Boring Facing

Drilling Thread cutting Reaming

TURRET LATHE:-

MODEL:- TL 25

MANUFACTURER:- BECO

It is a form of metal working lathe that is used for repetitive production of duplicate parts which by nature of their cutting process of are usually interchangeable.It evolved from the earlier lathes with the addition of the turret which is indexable tool holder that allows multiple cutting operationsto be performed ,each with a different cutting tool in easy and rapid succession.

PARTS OF TURRET LATHE:-

HEAD STOCK:-

It is located on the left side of the lathe.Head Stock houses the main spindle,speed change mechanism and change gears.In Head Stock of turret lathe,rapid shifting is done between at least two spindle speeds with a brake to stop the spindle very rapidly and automatic feeding out and clamping the bar stock which passes through spindle.

TURRET HEAD:-

In this type of lathe ,tail stock is replaced by turret head. Hexagonal turret head has six faces .Each face has one tool.The hexagonal turret can be indexed about its vertical axis,to bring each of its faces into the working position.The turret alongwith the saddle can be moved longitudinally either by a manual feed or a power feed.

STAR WHEEL:-

At the end of the turret working travel towards the spindle,the turret is moved back with the help of the star wheel.During this motion,it automatically indexes at end of movement thus bringing each of the six faces into working positions.

SQUARE CROSS SLIDE:-

In turret lathe,tool post is replaced by the square cross slide which can hold four tools.The movement of the tools on the cross slide is perpendicular to the lathe axis.

REAR CROSS SLIDE:-

In turret lathe,there is aspecail arrangement of Rear Cross Slide.Two more tools can be held in the rear cross slide.The tools in the rear cross slide areused to cut grooves,to face end or shoulders and to cut of the the work piece.There is no compound rest,tail stock and tool post in turret lathe.

OPERATIONS PERFORMED BY THE TURRET LATHE:-

A Turret can perfrom the following functions

Cutting Facing Thread cutting Grooving Drilling Boring Tapping

As turret lathes can perform operations with a whole set of cutting tools installed in a definite sequence on the turret and on the cross slide.Therefore turret lathes have higher production capacity than the centre lathes and are used in lot production.

EMCO LATHE:-

MODEL:- EMCO MAXIMAT V10 P

The Emco Maximat V13 was a very well made all geared head lathe that was supplied with a hardened bed as standard.It was probably the largest conventional centre lathe made by EMCO Company.

PARTS OF EMCO LATHE:-

BED:-

It provides foundation for whole machine and holds head stock ,tail stock and carriage in alignment.

HEAD STOCK:-

The head stock is normally mounted rigidly to bed and holds all mechanisms including the various kinds and combinations of pulleys or gears so that the spindle can be made to turn at different speeds.

Carriage:-

1. SADDLE:-

It is a casting that fits onto the top of the bed and slides along it.It moves longitudinally

2. CROSS SLIDE:-

It is mounted on the top of saddle and it moves across the workpiece so that facing operation to be performed and depth of cut can be adjusted.

3. COMPOUND REST:-

It is mounted on top of cross slide.It is usually graduated and used for taper turning.

4.TOOL POST:-

Tool is secured in the tool post to perform the different operations.It is mounted on the top of the compound rest.

5.APRON:-

It is vertical often flat and rectangular plate fastened to front of saddle and carries a selection of the gears and controls that allows the carriage to be power driven up and own the bed

TAIL STOCK:-

It is mounted on the right side of Emco lathe. Its arranged to slide along the bed and can be locked to any convenient point the upper part can be moved in and out. Its sliding member is known as quill in which dead centre is mounted.

LEAD SCREW:-

It is long threaded rod which advances carriage for thread cutting operations.

FEED RATES:-

It is unthreaded rod below lead screw that advances carriage for operations other than the thread cutting.

OPERATION PERFORMED BY EMCO LATHE:-

Facing Turning Grooving Boring Drilling Thread Cutting

UNIVERSAL MILLING MACHINE:-

Model Manufacturing:- Pak-Oerlikon

A Milling machine is a machine tool for the shaping of metal and other solid materials. In milling machine, work piece also moves against the rotating cutter.

PARTS OF MILLING MACHINE:-

Head Drive:-

It is that part of drive system that transforms electrical power from a motor to mechanical power in spindle. The drive system also provides machinist to change the speed of spindle and therefore the cutting tool.

Column:-

Sitting on base is the column whose main function is to hold the turret. The turret allows milling head to be rotated around column’s centre.

Ram:-

The over-arm (Ram) slides on turret and allows the milling head to be repositioned over the table.

Quill:-

The quill moves vertically in head and contains spindle in which cutting tools are installed.

Quill feed hand drill:-

It moves the quill up and down within the head as does the quill feed lever.

Knee:-

The knees move up and down by sliding on ways that are parallel to column.

Saddle:-

The saddle sits on knee and allows translation of work table.

Longitudinal Transverse Hand Wheel:-

It moves the worktable to the left and right.

Cross Traverse Hand Table:-

It moves the work table in and out.

Vertical Movement Crank:-

It moves the knee, saddle and work piece up and down.

TOOL GRINDER:-

It is a measure tool used for grinding which is a type of machining using an abrasive wheel as cutting tool. Each grain of abrasive on the wheel ‘s surface cuts a small chip from the work piece via shear deformation.

Mechanism:-

It removes material from the work piece by abrasion which can generate substantial amount of heat so they incorporate a coolant to cool the work piece so that it does not overheat and go outside its tolerance.

SURFACE GRINDING MACHINE:-

Manufacture:- Jones Shipment

A surface grinder is a machine tool used to provide precision ground surfaces either to a critical size or for the surface finish.

PARTS OF SURFACE GRINDING MACHINE:-

Table:-

The machine consists of a table that traverses both longitudinally and across the face of the wheel.

Hydraulics:-

The longitudinal feed is usually powered by hydraulics as may the cross feed.

Grinding wheel:-

The grinding wheel rotates in the spindle head and is also adjustable for height.

Chuck:-

Depending on the material, the work is generally held by the use of a magnetic chuck. This may be either an electromagnetic chuck, or a manually operated permanent magnetic chuck.

Materials Used For Surface Of Grinding wheel:-

Aluminium oxide, silicon carbide, diamond and cubic boron nitride are four commonly used abrasive materials for surface of grinding wheels of these materials, aluminium oxide is most common.

Cooloant:-

The machine has provision for the application of coolant as well as the extraction of metal dust.

CYLINDRICAL GRINDERS:-

Manufacturer:- Jones Shipment

Cylindrical grinders are a class of grinding machines on a work piece that are symmetrical about an axis of rotation. (e.g. cylindrical)

PARTS OF CYLINDRICAL GRINDER:-

Grinding Wheel:-

It is used as a cutting tool. In this grinder, wheel is held at a slight angle to the part so that there is a force feeding the part through the grinder is particularly efficient.

Work blade:-

In this machine grinding wheel rests on work table.

“In grinder both work piece and tool move and this grinder can also be used as internal grinder”

Coolant:-

This machine has provision for the application of the coolant to minimize the heat produced during grinding process.

SHAPER MACHINE:-

Model:- SH-460

Manufacturer:- Peco

A shaper is a machine tool used for shaping or surfacing metal and other material.

PARTS OF SHAPER MACHIINE:-

Table:-

The work piece mounts on a grid, box shaped table in front of machine. The height of table can be adjusted to suit this work piece and the table can traverse side ways underneath the reciprocating which is mounted on ram.

Ram:-

The ram slides back and forth above the work at the front end of the ram is a vertical tool slide that may be adjusted to either side of the vertical plane.

Tool slide:-

The tool slide holds tool post from where the tool can be positioned to cut the straight, flat surface on top of work piece.

Cutting Fluid:-

It may be employed to increase the finish and prolong the tool’s life.

Rotary Table:

Vertical shapers are generally fitted with rotary table to enable curved surface to be machined.

Tool Feed Handle:-

It can be turned to slowly feed the cutting tool into material as ram moves forwards and backwards.

Vice:-

It holds the material securely. It rests on steel table which can be adjusted so that it can be moved up and down and then locked in position.

Clutch Handle:-

Pulling back on clutch handle starts the ram movimg forward or backward

UPRIGHT DRLL PRESS:-

Model:- UD-50

The drill press is one of the most frequently used machine tools. They are used mainly for drilling holed but reaming, boring can also be accomplished with drill press.

PEDESTAL DRILL PRESS:-

Model:- PD-20

This drill press is used to drill holes in wood, plastic, aluminium, brass. Steel and most other common engineering materials.

PARTS OF DRILL PRESS:-

Drill Chuck:-

It is apart of drill press which is used to hold cutting tool such as twist drill, tap wrench, reamer etc.

Spindle:-

Spindle rotates the cutting tool which is clamped in drill chuck, after the work piece is secured in vise, it must be aligned under the spindle to perform desired operation on a particular place.

Feed Lever:-

It is used to raise and lower the spindle. The drill press allows operator to hand feed or power feed the tool into work piece.

Vise:_

Vise is used to hold work piece. In drill press cutting tool is rotated while work piece remains stationary.

Table:-

It is used to support work piece and also to clamp the parts being machined with drill press. It may be moving or stationay.

THE CONTROLS:-

Power/Range:-

This switch has 3 positions, high range, low range, and off. Low range is used when larger holes or harder materials need to be machined while high range is useful when small and softer material are being drilled.

Spindle Speed:-

Both high range and low range spindle speeds are changed using this control. The speed should only be changed while motor is running.

POWER HACKSAW:-

It is a type of hacksaw that is provided power either by an electric motor or connected to a stationary engine. When circular material is cut hacksaw is used.

Blades of Hacksaw:-

The hacksaw has blade which has reciprocating motions. The fixed material on the hacksaw is cutoff as a result of blades action.

Procedure of cutting circular material:-

The power hacksaw is easy to use. Firstly material is fixed in the vise of hacksaw at desired length. A switch of hacksaw turns on and lowers blade slowly on to the material. When material is finished cutting, the hacksaw stops automatically.

CNC MACHINE:-

They are modern machine and are in place of older production machines due to their ease of setting and operation. In this machine tools paths are programmed CAD/CAM processes, and then program is uploaded to machine. Machine’s output is totally dependent on the developed program because once the machine is set according to program, it works accordingly to program. This machine is safe to operator and is easy to use.

Experiment No. 2

OBJECTIVE:

Alignment test of lathe machine (BL-115).

Apparatus:

Dial gauge Magnetic stand Testing mandrel Steel rule Chuck key Dead centre

Tests to be performed:-

1. Check straightness of bed.2. Check taper hole in spindle.3. Check bed level of cross direction.4. Spindle axis parallel with bed.5. Tolerance of centers.

Procedure:-

In order to check alignment of lathe machine, we have performed the above mentioned tests as follows.

Straightness of bed:-

Place the dial gauge attached with magnetic stand on cross slide. Set the dial gauge in such a way that its tip touches the bed of lathe. Move the saddle in forward direction up to a particular length of bed say 300mm. Dial gauge shows different readings during this forward motion. Noted the readings of the dial gauge which is actually the deviation in straightness of

bed.

Taper hole in spindle:-

To check taper hole in spindle mount the tapered mandrel in tapered spindle (quill) of tail stock.

Set the dial gauge in such a way that its tip touches the surface of mandrel.

Move the saddle in forward direction above which dial gauge attached with magnetic stand is placed throughout the length of spindle.

Dial gauge show readings during this motion. Then noted the reading of dial gauge which is actually the deviation in tapered hole of

spindle.Bed level of cross direction:-

Placed the dial gauge attached with magnetic stand on cross slide. Set the dial gauge in such a way that its tip touches the surface of bed. Moved the cross slide across the bed and noted the value of dial gauge. The reading of dial gauge is actually the deviation in bed level of cross direction.

Spindle axis parallel with bed:-

Mounted the mandrel in spindle of head stock. Placed the dial gauge attached with magnetic stand on cross slide in such a way that its

tip touches the surface of mandrel. Move the saddle towards head stock. The dial gauge show different readings. Then noted the reading of dial gauge which is deviation in spindle axis parallel with bed. Also find circular deviation of spindle.

Tolerance of centers:-

Mounted live centre in headstock and dead centre. Fix the testing mandrel between live and dead centre. Placed the dial gauge attached with magnetic stand on cross slide so that its tip touches

the mandrel surface. Move the saddle in such a way that tip of dial gauge remains in contact throughout the

length of mandrel. Noted the reading of dial gauge which is actually the deviation in tolerance of centers.

Comments:-

Alignment test of any machine is very important in order to improve the accuracy of machine. Because if there is some error in alignment of machine, any product manufactured by it will not be accurate. So it is very important to perform alignment tests.

Test No Alignment test to be performed

Theoretical deviation

Practical deviation

Error

Positive Negative

1) Straightness of bed 0.02mm/300mm 0.014mm/300mm ---- -0.14mm

2) Taper hole in spindle 0.005mm/300mm 0.29mm/195mm +0.29mm ----

3) Bed level of cross direction

0.02mm/300mm 0.08mm/120mm

---- -0.08mm

4)

5)

Spindle axis parallel with bed

Longitudinal

Circular

Tolerance of centers0.01mm/300mm

----

0.01mm/1000mm

0.12mm/270mm

0.2mm/30mm

0.48mm/450mm

0.12mm

----

0.48mm

----

-0.2mm

----

OBSERVATIONS :

TEST NAME DISTANCE MOVED ERROR

EXPERIMENT NO :- 3

OBJECTIVE:-

Alignment test of drilling machine (UD - 50)

Apparatus:-

Dial gauge. Magnetic stand. Testing mandrel. Spirit level. Steel rule.

Test to be Performed:-

Test No: 1

To check straightness of spindle.

Test No: 2

To check taper hole in spindle.

Test No: 3

To check straightness of the vertical column.

Test No: 4

To check the working table.

Procedure:-

In order to check the alignment of drilling machine, we have performed the above mentioned tests as follows:

1) To check straightness of spindle :-

Setup the magnetic stand on vertical column of drill. Adjust the dial gauge in it, in such a way that the dial gauge knob touches vertical

spindle. Now move the spindle upward / downward using the hand wheel such that dial gauge

knob slides over it. Note the maximum value of deflection of the dial gauge needle in either direction to

check the straightness of spindle.

2) To check taper hole in spindle:-

First of all, fix the testing mandrel in the vertical spindle taper hole. Next setup the magnetic stand along with the dial gauge on the vertical column in such a

way that dial gauge knob just touches the mandrel’s surface. Adjust the needle zero position of the dial gauge. Now to check the taper hole in the vertical spindle of the drill, move the spindle

upward / downward through 300 mm with the help of hand wheel in such a way that the knob of dial gauge slides over the mandrels surface and while doing. So note down the maximum value of gauge deflection.

3) To check the straightness of vertical column:-

First of all, fix the magnetic stand on working table of drill and set the magnetic stand on working table of drill and set the dial gauge in it such that the knob of dial gauge touches the vertical column of drill and adjust the needle to zero position.

Now with the help of a hand wheel (provided at lower side of drill) move the table upward , over a distance of 300 mm. While doing so, note down the maximum dial gauge value either direction for present value of the test.

4) To check the working table :-

In order to check the straightness of working table just place the spirit level on working table of drill and see whether it’s bubble is in it’s center or not.

OBSERVATIONS :

TEST NAME DISTANCE MOVED ERROR

Positive Negative

1. Straightness of spindle

Linear Circular

100 mm

Dia 470 mm

0

0.01

-0.02

-0.04

2. Taper hole in spindle

Linear circular

100 mm

Dia 34.5 mm

0.015

0.14

0

-0.05

3. Straightness of vertical column

300 mm 0 -0.04

4. Straightness of working table

0.1 m at 1 m from right to left

EXPERIMENT NO. 4

OBJECTIVE:-

Manufacture a work piece on lathe machine according to given dimensions.

Apparatus:-

Lathe machine Raw material for work piece Facing tool Turning tool Threading tool Abrasive finishing paper

Theory:-

Lathe Machine:-

The lathe is the forerunner of all machine tools. The first application of the lathe principle was probably the potter’s wheel. This machine rotated a mass of clay and enabled the clay to be formed into a cylindrical shape.

The modern lathe operates on same basic principle. The work is held and rotated on its axis while the cutting tool is advanced along the lines of a desired cut. The lathe is one of the most versatile machine tools used in industry. With suitable attachments, the lathe may be used for turning, taper turning, screw cutting, facing, drilling, boring etc. by using cutting tools. The cutting tool may be fed either

parallel or at right angles to axis of work. Cutting tool may also be fed at an angle to axis of work for

machining tapers.

Cutting Speed:

Lathe work cutting speed (CS) may be defined as the rate at which a point on the work circumference travels past the cutting tool. It is usually expressed in feet per minute (ft/min) or in meters per minute (m/min). Cutting speed depends on the type of material being cut. If cutting speed is too high, the cutting tool edge breaks rapidly. With too slow cutting speed, time will be lost for machining operation.

Inch Calculations:

Cutting speed = ∏ DN/12

where N= No. of revolutions per minute of spindle

D = Diameter of workpiece to be turned

Metric Calculations:

Cutting speed = DN/320

Lathe Feed:

The feed of a lathe may be defined as distance the cutting tool advances along the length of the work for every revolution of spindle. For general purpose machining, 0.010 to 0.015 in (0.25-0.4mm) feed for roughing and 0.003 to 0.005 in (0.07-0.012mm) feed for finishing is recommended.

Tool Geometry:-

Lathe Cutting Tools:

Most commonly used lathe cutting tools are as follows:

1. Facing tool:

Facing is a process of reducing length of workpiece to obtain desired size, shape and accuracy. The tool used for facing is known as facing tool.

2. Turning tool:

Turning is a process of reducing diameter of workpiece to obtain desired size, shape and accuracy. The tool used for turning is known as turning tool.

3. Threading tool:

Threading is a process of making threads on workpiece. The tool used for threading is known as threading tool.

4. Boring tool:

Boring is a process of enlargement of hole after drilling. The tool used for boring is known as boring tool.

5. Parting tool:

Parting is a process of separating workpiece from rest of raw material or any other component. The tool used for parting is known as parting tool.

6. Finishing tool:

Finishing is a process of making the surface of workpiece smooth. It can be performed by using abrasive paper or finishing tool.

Grooving, undercutting Facing

or parting

Threading 60 Finishing

Threading ACME

Cutting tool geometry also includes proper clearance and rake angles ground on tool bit.

a) Side cutting edge angle:

It is angle the cutting edge forms with side of tool shank. It varies from 10° - 20° .

b) End cutting edge angle:

It is the angle formed by the end cutting edge and a line at right angles to the centerline of tool bit. This angle varies from 5° – 15° for roughing cut and from 15° – 30° for general purpose turning tools.

c) Side clearance angle:

It is an angle ground on flank of tool below cutting edge. It is generally 6° – 10°.

d) End clearance angle:

It is the angle ground below the nose of tool bit, which permits cutting tool to be fed into work. It is generally 10° – 15°.

e) Side rake angle:

It is an angle at which face is ground away from cutting edge. It is generally 14°.

f) Back rake angle:

It is the backward slope of tool face away from the nose. This angle is generally 20°.

g) Angle of keenness:

It is the included angle produced by grinding side rake and side clearance on tool bit. This angle is generally 90° for harder materials.

Lathe operations performed on workpiece:-

1. Facing:

It is a process of reducing the length of workpiece to obtain desired size, shape and accuracy. It is usually done by a facing tool.

Workpieces to be machined are generally cut a little longer than required and then end-faced to the proper length. By facing operation, the ends of a workpiece are to be machined square with its axis.

2. Turning:

It is a process of reducing the diameter of workpiece to obtain desired size, shape and accuracy. It is usually performed by a turning tool. By using turning process, diameters of different parts of workpiece are to be maintained.

3. Step turning:

It is a process to make different steps having different diameters such as in workpiece different diameters 14.4mm, 20.3mm, and 23.5mm are obtained by step turning.

4. Threading:

It is a process of making threads on workpiece, by using threading tool.

Thread cutting on lathe is a process that produces a helical ridge of uniform section on a workpiece. This is performed by taking successive cuts with a threading tool bit of same shape as the thread form required.

We have to make threads of 11 T.P.I. on workpiece up to a length of 55.5mm.

5. Finishing:

It is a process to make the surface of workpiece smooth. It is very important and it is usually performed at the completion of other lathe operations. It is usually performed by using abrasive paper, filing or finishing tool.

Procedure to make required workpiece on lathe:-

1. Cut a piece of material from which the workpiece has to be made slightly longer than the required length by using hacksaw.

2. Mounted the workpiece in chuck of lathe and firstly performed facing operation to reduce the length of workpiece up to required length and to make end face smooth.

3. Performed the turning operation up to the length of 55.5mm by using turning tool, to attain the required diameter of 14.4mm.

4. Performed the step turning to attain the diameters of 20.3mm and 23.5mm up to the lengths of 16mm and 60.5mm respectively.

5. Perform same procedure of step turning on the other side of workpiece.6. Perform the threading operation on both sides of workpiece to make threads of 11 T.P.I. up to

the length of 55.5mm.7. At the end finishing process has to be performed to make the surface of workpiece smooth.

WORKPIECE MANUFACTURED ON LATHE (All units in mm)

Standard pitch table:- (From 3mm to 12mm)

Nominal diameter (mm)

Thread Pitch(mm)

3 0.54 0.75 0.86 17 18 1.2510 1.512 1.75

Standard threads T.P.I.:- (From ⅛″-½″)

Nominal size T.P.I

⅛″ 27¼″ 18⅜″ 18½″ 14

Formula to find drill size when performing internal threading through taps:

The tap drill size for any American, National or unified thread can be found easily by applying this simple formula.

TDS= D- 1/N

where TDS = tap drill size

D = major diameter of tap

N = number of threads per inch

EXPERIMENT NO. 5

OBJECTIVE :-

CNC programming and metal cutting

Introduction:-

The Boxford 160 TCL is British made training computer lathe featuring ISO format machine tool programming. It is a integrated bench top turning system system specifically designed for educational and training installations. It can cut sreel,brass, wood, aluminium, and plastics.It is ideally suited for classroom yet is capable of cutting steel to close tolerances, special accessories also allow the machining of wood and plastics.

The lathe has a programming length built in touch sensitive control panel with programming and variable speed of spindle from 40 to 3200 rpm. It an error is made in the block of CNC code. The result is displayed on computer screen and is easily removed on computer.

BOXFORD 160 TRAINING COMPUTER LATHE (TCL)

Capacity and limits

1) Spindle speed rangeRange # 1 320-----------3200 rpm

Range # 2 160-----------1600 rpm

Range # 3 80-------------800 rpm

Range # 4 40-------------400 rpm

Range # 1 gives maximum speed and Range # 4 maximum torque.

2) Feed rate (G01)

Feed rate 10mm/min---500mm/min

3) Rapid transverse (G00) Rapid transverse : 1200mm/min

4) x axis travels traveling :- 75mm(max)

5) z axis traveling :- 125mm

6) spindle bore :- 20mm

7) Main motor :- 44 KW

8)Unit selection:-

1) Imperial dimension format (G70)XX.XXX

12.345

Metric dimension format (G71)

Metric dimension is expressed as

XXX.XX

123.45

Programming Coordinates:-

Absolute dimensions:- (G90)

In this system,, all programming coordinates are located from a fixed zero absolute point. This

dimension is generally used for 2 axis machine.

Incremental dimensions :- (G91)

In an incremental numerical control programming each coordinate location is given in terms of distance from previous position of tool. This dimension is generally used for 3 axis machine.

Description of line number used in programming sheet:-

Line # 10 :- select absolute or incremental dimension (G90 or 91)

Line # 20:- unit selection (imperial or metric)

Line #30 ;- tool park position (x and z axis)

Line # 40 :- spindle start (reverse or forward)

Preparatory codes:- (G codes)

These codes are used to change the machining process performed in CNC. Some commonly used G codes are as follows.

Codes Function

G00 Rapid transverse movement

G01 Linear interpolation

G02 Circular interpolation

G03 Circular interpolation

(counter clockwise)

G04 Time Duell

G70 Imperial dimensions

G71 Metric dimensions

G81 Outer dia turning cycle

G82 Facing or grooving

G90 Absolute dimensioning

G91 Incremental dimensioning

G94 Feed per minute

G95 Feed per revolution

G96 Constant surface speed

G97 Constant RPM

Miscellaneous codes:- (M codes)

These codes are generally used to change the behavior of machine. Some commonly used M codes are as follows.

Codes Function

M02 Measure end of program for the single quantity

M03 Start spindle forward

M04 Start spindle reverse

M05 Start spindle

M06 Tool change

M30 Mark the end of program for repeat quantity

M39 Closing automatic chuck

M40 Opening automatic chuck

M81 Output ON/OFF

M97 Continuous manufacture

M99 Continuous code

Program:-

In catalogue 9

Enter bar information:

Outer Diameter: 50mm

Internal Diameter (in case of pipe) : 0mm

Length : 100mm

Material:

1→ For mild steel or similar

2→ For Brass, Aluminium or similar

3→ For plastics, wax

Programming sheet:

Line G M X Z I K F SN10 90N20 71N30 55 5 1 6N40 04 2000N50 50 0N60 47N70 01 -70 10N80 48N90 0N100 44N110 01 -70 10N120 45N130 0N140 40N150 01 -70 10N160 42N170 0N180 81 20 -30 20 10N190 37

N200 -30N210 01 40 -45 10N220 -30N230 34N240 01 40 -45 10N250 -30N260 30N270 01 40 -45 10N280 -30N290 27N300 01 40 -45 10N310 -30N320 24N330 01 40 -45 10N340 -30N350 20N360 01 40 -45 10N370 -2N380 20N390 01 -4 10N400 0N410 21N420 02

where

L→ Line No.

G,M→ Codes

X,Z→ Axis

I→ Tool number

K→ Turret number

F→ Feed rate

S→ Spindle speed

WORKPIECE MANUFACTURED ON 160 TCL (All units in mm)

Experiment No. 6

Study of Universal Milling machine and Gear cutting

Milling machines are machine tools used to produce one or more machined surfaces accurately

on a piece of material, the work piece, this is done by one or more rotatery milling cutters having

single or multiple cutting edges.

Universal milling machine:

It is a versatile machine tool that can handle a variety of operations normally performed by other

machine tools. It is used not only for the milling of flat and irregular shaped surfaces but also for

gear and thread cutting, drilling, boring, reaming and slotting operations.

Parts of universal milling machine:

1) Base:

The base gives the support and strength to the machine and act as a reservoir for cutting

fluid.

2) Column:

The column is the main supporting frame. It is a heavy box like structure. Inside the

column, there is space for motor and driving mechanism. The face of the column is a very

accurate slide

3) Knee:

The knee is attached to the column face and may be vertically moved on the column face

either manually or accurately or automatically. It houses the feed mechanism.

4) Saddle:

The saddle is fitted on top of knee and may be moved in or out either manually by means

of the cross feed hand wheel or automatically by crosses feed engaging lever.

5) Table:

The table rests on guide ways in saddle and travels longitudinally in a horizontal plane. It

supports the work.

6) Spindle:

The spindle provides the drive for arbors, cutters and attachments used on a milling

machine.

7) Over arm:

The over arm provides for correct alignment and support of arbor and provide

attachments. I t can be adjusted and locked in various positions, depending on the length

of arbor and position of cutter.

8) Arbor support:

The arbor support is fitted to over arm and can be clamped at any location on over arm.

Its purpose is to align and support various arbors and attachments.

9) Arbor:

It is a tapered portion and end of arbor is free, so it can fluctuate.

10) Elevating Screw:

It is controlled manually or automatically. It gives upward and downward movements to

knee and table.

Indexing

It is a process of maintaining same distance or gap between grooves. It can be performed

by holding the work piece and rotating it the exact amount for each groove or slot to be

cut.

Methods of Indexing

1) Direct Indexing:

In direct indexing, the index plate is directly mounted on the dividing head spindle.

The intermediate use of worm and worm wheel is avoided. For indexing, the index

pin is pulled out on a hole, the work and the index plate are rotated the desired

number of holes and the pin is engaged. Direct indexing is the most rapid method of

indexing but fractions of a complete turn of spindle are limited to those available with

the index plate.

2) Simple Indexing:

In simple or plain indexing, an index plate selected for the particular application is

fitted on worm shaft and locked through a locking pin. To index the work through any

required angle, the index crank pin is withdrawn from a hole in index plate. This

spindle and hence work is indexed through the required angle by turning the index

crank through a calculated number of whole revolutions and holes on one of hole

circles after which index pin is relocated in required hole.

To calculate the indexing or number of turns of crank for most divisions, it is

necessary only to divide 40 by number of divisions (N) to be cut or

Indexing=40/N

Where N = No. of teethes to be cut

The usual ratio is 40 turns of index crank to 1 turn of spindle, in other words a ratio of

40 to 1. Now since the index crank make 40 revolutions to 1 of the spindle, one

revolution of crank would cause spindle to rotate 1/40 revolution.

3) Compound Indexing:

When none of the index plates has a hole circle which would enable the work to be

divided by simple indexing method, more involved methods are employed. One

method is compound indexing. The compound indexing is achieved in two stages, by

using two different hole circles of one index plate.

By a movement of the crank in the usual way as in simple indexing, say n1

holes in hole circle N1, with the lock pin engaged in circle N2 of index plate.

By adding or subtracting a further movement by rotating the crank and the

index plate together forward or backward through n2 spaces in the N2 circle by

disengaging the locking pin of index plate so that it is free to turn.

4) Angular Indexing:

When the angular distance between divisions is given instead of the number of

divisions, the setup for simple indexing may be used, however the method of

calculating the indexing is changed. One complete turn of index crank turns the work

one fortieth of a turn or one fortieth of 360° which equals to 9°.

When angular dimension is given in degrees then,

Indexing in Degrees = No. of degrees required / 9

If dimensions are given in degree and minutes, then

Indexing in Minutes = No. of minutes required / 540

5) Differential Indexing:

When it is impossible to calculate the required indexing by simple indexing method,

that is when fraction 40/N cannot be reduced to a factor of one available hole circles,

then differential indexing is used.

With this method, the index plate must revolve either forward or backward a part of

turn while index crank is turned to attain proper spacing or indexing. In differential

indexing, the index crank rotates dividing head spindle, spindle rotates index plate

after locking pin has been disengaged by means of change gears connecting the

dividing head spindle and worm shaft. The rotation of plate may be in same direction

(positive) or in opposite direction (negative) of index crank. This change of rotation is

affected by an idler gear or gears in gear train. When it is necessary to calculate the

indexing for a required number of divisions by differential method, a number is chose

close to required divisions that can be indexed by simple indexing.

Index plate:

Dividing needs are usually furnished with a set of three index plates having six

concentric holes with different number of equally spaced hole side. A typical set has

following number of holes.

Plate # 1: 15, 16, 17,18,19,20

Plate # 2: 21, 23, 27,29,31,33

Plate # 3: 37, 39, 41,43,47,49

Gears:

Gears are used to transmit power from one shaft to other by engaging teeth.

Gear terminologies:

Knowledge of more common gear terms is desired to understand gearing and to make

calculations necessary to cut a gear.

Circular pitch:

It is distance of one point on one tooth to the corresponding point on next tooth.

Circular pitch=length of arc ABC

=circumference of pitch circle / number of teeth

Or with symbols

C.P=3.1416*D / N ...... (i)

Where

C.P=circular pitch

D=Diameter of pitch circle

N=Number of teeth

From (1)

N=3.1416*D / C.P ......(ii)

D=CP*N / 3.1416 ......(iii)

Diameteral pitch:

It is the ratio of number of teeth for each inch of pitch diameter of the gear.

Diameter pitch=number of teeth/pitch of circle diameter

D.P=N / D .....(i)

From (i) following relations are obtained

N=D.P*D

D=N/D.P

Relation Between circular & diametral pitch:

Diametral pitch=3.1416/diametral pitch .....(i)

Sometimes it is convenient to change circular to diametral pitch or vice versa. So

Circular pitch=3.1416/diametral pitch .....(ii)

Addendum:

It is radial distance between the pitch circle and outside diameter or height of the

tooth above the pitch circle

In general

Addendum = 1 / diametral pitch

Deddendum:

It is the radial distance from the pitch of the circle to the bottom of tooth space.

Deddendum is equal to addendum. Accordingly, deddendum is found in same way as

an addendum that is,

Deddendum = 1 \ Diametral Pitch

Working Depth:

The sum of addendum and deddendum is called the working depth. It is the actual

theoretical length of the tooth.

Clearance:

It is the radial distance between the top of one tooth and the bottom of mating tooth

space. Gear must be so proportioned that when a tooth is in mesh with the groove or

space between it and adjacent tooth, the top of the tooth will not touch the bottom of

the groove, the reason for this, it is impossible to machine the teeth to the exact

dimension and accordingly there must be a margin of space to allow for any slight

errors and this margin is called the clearance.

Clearance = .157 \ DP

Face and Flanks:

By definition the face of tooth is that part of the tooth curve which lies between the

addendum and the pitch circle.

The flank of a tooth is that part of the tooth curve that lies between the pitch circle

and the deddendum circle.

Circular thickness

It is the tooth thickness measured on the pitch circle. It is also known as the Arc

Thickness.

Module :*( Metric gears)

It is the pitch diameter of the gear divided by the no. of teeth. It is an actual dimension.

Pitch Circle:

It is a circle that has the radius of half the pitch diameter with its center at the axis of

the gear.

Pressure Angle:

It is an angle formed by line through the point of contact of two mating teeth and the

tangent to the two base circles and a line at right angles to center line of gear.

Root Circle:

It is the circle formed by the bottom of tooth spaces.

Whole Depth:

It is full depth of tooth or the distance equal to addendum deddendum.

Cutting Spur Gears:

Eight cutters for each pitch are as follows,

No. 8 cutter will cut gear from 135 teeth to a rack.

No.7 will cut gear from 55 to 135 teeth.







Procedure:

Mounted the milling cutter on the milling machine arbor. Make sure that the

cutter teeth point is in the direction of arbor rotation.

Mounted the work-piece in milling machine.

Switch on the milling machine and run the work under the cutter.

Set the index plate such that the crank pin is inserted in any one hole of 49 hole

circle.

Raise the table until the cutter just touches the top of work-piece.

Now set the automatic feed according to the depth of tooth. After cutting 1st tooth,

move the work-piece back, loose the knee clamp, set the crank pin in 35 holes out

of 49 hole circle.

Again placed work-piece under cutter after tightening the clamp.

Cut the 2nd tooth to its whole depth.

Repeat this procedure till the completion of total teeth (560.

Now remove the work-piece and cutter from machine.

Circular pitch whole depth

Top Dedendum

Working depth Thickness

Pitch diameter addendum

Face clearance

Flank

Module

Outside diameter outside circle

Root circle

Dimensions of Gear to Be Cut:

Outer Diameter of Gear = 87.8 mm

No. of Teeth = 56

Whole Depth = 3.27 mm

Module = 1.51

But Module Used = 1.5

Index Plate = 17, 19, 21,24,29,33,39,43,49

So, by using simple indexing,

40\n = 40\56 = 5\7 = 5*3\7*3 = 15\21

i.e. 15 holes out of 21 hole circle

Or

5*7\7*7 = 35\49

i.e. 35 holes out of 49 hole circle.

Lab Manual

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