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Module 4

General Purpose Machine Tools

Version 2 ME, IIT Kharagpur




Lesson 23

Construction, Operation and Tool

layout in Semiautomatic and

Automatic lathes.





Instructional objectives This lesson will enable the students ; (i) Illustrate the constructional features and uses of semiautomatic and automatic lathes. (ii) Show the kinematic system and explain the working principles of semiautomatic and automatic lathes of common use. (iii) Plan and visualise tool layout for machining in semiautomatic and automatic lathes. (i) Constructional Features And Uses Of General Purpose Semiautomatic And Automatic Lathes. Automation is incorporated in a machine tool or machining system as a whole for higher productivity with consistent quality aiming meeting the large requirements and overall economy. Such automation enables quick and accurate auxiliary motions, i.e., handling operations like tool work mounting, bar feeding, tool indexing etc. repeatably with minimum human intervention but with the help of special or additional mechanism and control systems. These systems may be of mechanical, electro-mechanical, hydraulic or electronic type or their combination. It is already mentioned that according to degree of automation machine tools are classified as,

Non automatic where most of the handling operations irrespective of processing operations, are done manually, like centre lathes etc.

Semiautomatic Automatic where all the handling or auxilliary operations as well as

the processing operations are carried out automatically. General purpose machine tools may have both fixed automation or flexible automation where the latter one is characterised by computer Numerical Control (CNC). Amongst the machine tools, lathes are most versatile and widely used. Here automation of lathes only have been discussed. The conventional general purpose automated lathes can be classified as,

(a) Semiautomatic : capstan lathe (ram type turret lathe) turret lathe multiple spindle turret lathe copying (hydraulic) lathe

(b) Automatic : Automatic cutting off lathe Single spindle automatic lathe

Swiss type automatic lathe multiple spindle automatic lathes





The other categories of semiautomatic and automatic lathes are :

Vertical turret lathe Special purpose lathes Non conventional type, i.e., flexibly automatic CNC lathes, turning

centre etc. (a) Semiautomatic lathes The characteristic features of such lathes are ;

some major auxiliary motions and handling operations like bar feeding, speed change, tool change etc. are done quickly and consistently with lesser human involvement

the operators need lesser skill and putting lesser effort and attention

suitable for batch or small lot production costlier than centre lathes of same capacity.

Capstan and Turret lathes The semiautomatic lathes, capstan lathe and turret lathe are very similar in construction, operation and application. Fig. 4.7.1 schematically shows the basic configuration of capstan lathe and Fig. 4.7.2 shows that of turret lathe.

Fig. 4.7.1 Schematic configuration of capstan lathe.





Guide rod

Fig. 4.7.2 Schematic configuration of turret lathe. In contrast to centre lathes, capstan and turret lathes

are semiautomatic possess an axially movable indexable turret (mostly hexagonal) in

place of tailstock holds large number of cutting tools; upto four in indexable tool post

on the front slide, one in the rear slide and upto six in the turret (if hexagonal) as indicated in the schematic diagrams.

are more productive for quick engagement and overlapped functioning of the tools in addition to faster mounting and feeding of the job and rapid speed change.

enable repetitive production of same job requiring less involvement, effort and attention of the operator for pre-setting of workspeed and feed rate and length of travel of the cutting tools

are relatively costlier are suitable and economically viable for batch production or small

lot production. There are some differences in between capstan and turret lathes such as,

Turret lathes are relatively more robust and heavy duty machines Capstan lathes generally deal with short or long rod type blanks

held in collet, whereas turret lathes mostly work on chucking type jobs held in the quick acting chucks

In capstan lathe, the turret travels with limited stroke length within a saddle type guide block, called auxiliary bed, which is clamped on the main bed as indicated in Fig. 4.7.1, whereas in turret lathe, the





heavy turret being mounted on the saddle which directly slides with larger stroke length on the main bed as indicated in Fig. 4.7.2

One additional guide rod or pilot bar is provided on the headstock of the turret lathes as shown in Fig. 4.7.2, to ensure rigid axial travel of the turret head

External screw threads are cut in capstan lathe, if required, using a self opening die being mounted in one face of the turret, whereas in turret lathes external threads are generally cut, if required, by a single point or multipoint chasing tool being mounted on the front slide and moved by a short leadscrew and a swing type half nut.

Fig. 4.7.3 and Fig. 4.7.4 are showing the pictorial views of a typical capstan lathe and a horizontal turret lathe respectively.

Fig. 4.7.3 Pictorial view of a capstan lathe

Ram type turret lathes, i.e., capstan lathes are usually single spindle and horizontal axis type. Turret lathes are also mostly single spindle and horizontal type but it may be also

Vertical type and Multispindle type

Some more productive turret lathes are provided with preoptive drive which enables on-line presetting and engaging the next work-speed and thus help in reducing the cycle time.





Ramp type turret lathes, i.e., capstan lathes are usually single spindle and horizontal axis type. Turret lathes are also mostly single spindle and horizontal type but it may be also

Vertical type and Multi-spindle type

Some more productive turret lathes are provided with pre-optive drive which enables on-line presetting and engaging the next work-speed and thus help in reducing the cycle time. Multi-spindle Vertical Turret lathe

Fig. 4.7.4 Pictorial view of a turret lathe. Multiple spindle Vertical Turret lathe Turret lathes are mostly horizontal axis single spindle type. The multiple spindle vertical turret lathes are characterised by :

Suitably used for large lot or mass production of jobs of generally ; chucking type relatively large size requiring limited number of machining operations

Machine axis vertical for lesser floor space occupied easy loading and unloading of blanks and finished jobs relieving the spindles of bending loads due to job

weight. Number of spindle four to eight.

Fig. 4.7.5 visualise the basic configuration of multiple spindle vertical turret lathes which are comprised mainly of a large disc type spindle carrier and a tool holding vertical ram as shown.





Such vertical turret lathes are of three categories : Parallel processing type : The spindle carrier remains stationary. Only the tool slides move with cutting tools radially and axially. Identical jobs (say six) are simultaneously mounted and machined in the chucks parallely at all stations each one having same set of axially and / or radially moving cutting tools.

Fig. 4.7.5 Basic configuration of multispindle automatic vertical lathe

Loading unloading station

Progressively processing type : The spindle carrier with the blanks fitted in the chucks on the rotating spindle is indexed at regular interval by a Geneva mechanism. At each station the job undergoes a few preset machining work by the axially and / or radially fed cutting tools. The blank getting all the different machining operations progressively at the different work stations is unloaded at a particular station where the finished job is replaced by another fresh blank. This type of lathes are suitable for jobs requiring large number of operations.





Continuously working type : Like in parallel processing type, here also each job is finished in the respective station where it was loaded. The set of cutting tools, mostly fed only axially along a face of the ram continuously work on the same blank throughout its one cycle of rotation along with the spindle carrier. The tool ram having same tool sets on its faces also rotate simultaneously along with the spindle carrier which after each rotation halts for a while for unloading the finished job and loading a fresh blank at a particular location. Such system is also suitable for jobs requiring very few and simple machining operations. Hydraulic copying (tracer controlled) lathes Jobs having steps, tapers and / or curved profiles, as typically shown in Fig. 4.7.6, are conveniently and economically produced in batch or lot in semiautomatically operated tracer controlled hydraulic copying lathe. The movement of the stylus along the template provided with the same desired job-profile) is hydraulically transmitted to the cutting tool tip which replicates the template profile.

Fig. 4.7.6 A typical job suitable for copy turning.

(b) General Purpose Automatic lathes Automatic lathes are essentially used for large lot or mass production of small rod type of jobs. Automatic lathes are also classified into some distinguished categories based on constructional features, operational characteristics, number of spindles and applications as follows

Single spindle Automatic cutting off lathes Automatic (screw cutting) lathe Swiss type automatic lathe

Multispindle automatic lathe





Automatic cutting off lathe These simple but automatic lathes are used for producing short work pieces of simple form by using few cross feeding tools. In addition to parting some simple operations like short turning, facing, chamfering etc. are also done. Single spindle automatic lathe The general purpose single spindle automatic lathes are widely used for quantity or mass production (by machining) of high quality fasteners; bolts, screws, studs etc., bushings, pins, shafts, rollers, handles and similar small metallic parts from long bars or tubes of regular section and also often from separate small blanks. Fig. 4.7.7 shows a typical single spindle automatic lathe. Unlike the semiautomatic lathes, single spindle automats are :

preferably and essentially used for larger volume of production i.e., large lot production and mass production

used always for producing jobs of rod, tubular or ring type and of relatively smaller size.

run fully automatically, including bar feeding and tool indexing, and continuously over a long duration repeating the same machining cycle for each product

provided with upto five radial tool slides which are moved by cams mounted on a cam shaft

of relatively smaller size and power but have higher spindle speeds

Fig. 4.7.7 A typical single spindle automatic lathe.





Swiss type automatic lathe The characteristics and applications of these single spindle automatic lathes are : In respect of application :

Used for lot or mass production of thin slender rod or tubular jobs, like components of small clocks and wrist watches, by precision machining; o Job size (approximately)

Diameter range 2 to 12 mm Length range 3 to 30 mm

Dimensional accuracy and surface finish almost as good as provided by grinding In respect of configuration and operation

The headstock travels enabling axial feed of the bar stock against the cutting tools as indicated in Fig. 4.7.8

There is no tailstock or turret High spindle speed (2000 10,000 rpm) for small job diameter The cutting tools (upto five in number including two on the rocker arm)

are fed radially Drilling and threading tools, if required, are moved axially using

swivelling device(s) The cylindrical blanks are prefinished by grinding and are moved

through a carbide guide bush as shown.

Fig. 4.7.8 Basic principle of Swiss type automatic lathe.





Multispindle automatic lathes For further increase in rate of production of jobs usually of smaller size and simpler geometry. Multispindle automatic lathes having four to eight parallel spindles are preferably used. Unlike multispindle turret lathes, multispindle automatic lathes ;

are horizontal (for working on long bar stocks) work mostly on long bar type or tubular blanks

Multiple spindle automats also may be parallel action or progressively working type. Machining of the inner and outer races in mass production of ball bearings are, for instance, machined in multispindle automatic lathes. (ii) Kinematic Systems And Working Principles Of Semi Automatic And Automatic Lathes The kinematic systems and basic principles of working of the following general purpose semi-automatic and automatic lathes of common use have been visualised and briefly discussed here :

(a) Semi-automatic lathes : Capstan and single spindle turret lathe Hydraulic copying lathe

(b) Automatic lathes

Single spindle automatic (screw cutting) lathe Swiss type automatic lathe

Kinematic system and working principle of capstan lathe Like general configurations and applications, the basic kinematic systems are also very similar in capstan lathes and turret lathes (particularly single spindle bar and horizontal types) in respect of their major functions, i.e.,

bar feeding mechanism turret moving and indexing speed and feed drives

Bar feeding mechanism of capstan lathe Fig. 4.7.9 typically shows the kinematic arrangement of feeding and clamping of bar stock in capstan lathes. The bar stock is held and tightly clamped in the push type spring collet which is pushed by a push tube with the help of a pair of bell-crank levers actuated by a taper ring as shown in Fig. 4.7.9. Bar feeding is accomplished by four elementary operations;

unclamping of the job by opening the collet bar feed by pushing it forward clamping of the bar by closing the collet free return of the bar-pushing element





After a job is complete and part off, the collet is opened by moving the lever manually rightward to withdraw the push force on the collet. Further moving of the lever in the same direction causes forward push of the bar with the help of the ratchet paul system shown. After the projection of the bar from the collet face to the desired length controlled by a pre-set stop stock generally held in one face of the turret or in a separate swing stop, the lever is moved leftward resulting closing of the collet by clamping of the barstock. Just before clamping of the collet, the leftward movement of the lever pushes the bar feeder (ratchet) back freely against the paul. Turret indexing mechanism in capstan and turret lathes Turret indexing mechanism of capstan and single spindle turret lathe is typically shown schematically in Fig. 4.7.10. The turret (generally hexagonal) holding the axially moving cutting tools have the following motions to be controlled mechanically and manually ;

forward axial traverse comprising; quick approach manually done by rotating the pinion as

shown slow working feed automatically by engaging the clutch stop at preset position depending upon the desired length

of travel of the individual tools o quick return manually done by disengaging the clutch and

moving the turret back o indexing of the turret by 60o (or multiple of it) done manually by

further moving the turret slide back.

Fig. 4.7.9 Typical bar feeding mechanism in capstan lathe. Just before indexing at the end of the return stroke, the locking pin is withdrawn by the lever which is lifted at its other end by gradually riding against the hinged wedge as indicated in Fig. 4.7.10 (a). Further backward travel of the turret slide causes rotation of the free head by the indexing pin





and lever as indicated in Fig. 4.7.10 (b). Rotation of the turret head by exact angle is accomplished by insertion of the locking pin in the next hole of the six equispaced holes. After indexing and locking, the turret head is moved forward with the next cutting tool at its front face when the roller of the lever returns through the wider slot of the wedge without disturbing the locking pin as indicated in the figure. The forward motion of the turret head is automatically stopped when the set-screw corresponding to the working tool is arrested by the mechanical stop. The end position and hence length of travel of the tool is governed by presetting the screw. There are six such screws, each one corresponds with particular face or tool of the turret. The drum holding those equispaced six screw with different projection length is rotated along with the indexing (rotation) of the turret head by a pair of bevel gears (1:1) as indicated in Fig. 4.7.10 (a). The bottom most screw, which corresponds with the tool on the front face of the turret, when hits or touches the stop, the turret movement is stopped either manually by feeling or automatically by disengaging the clutch between the feed rod and the turret slide. (a) sectional view

stop

(b) top (inner) view

Fig.4.7.10 Turret indexing in capstan and turret lathe.





Kinematics and working principle of hydraulic copying lathe Hydraulic drive is often preferably used in some machine tools for smooth motions without jerk and noise, self lubrication, flexible transmission system and stepless variation in speed and feed despite the limitations like larger space requirement, oil leakage, difficult maintenance etc. Fig. 4.7.11 typically shows the circuitry of a hydraulically driven (tool travel) drilling machine. The direction and length of travel of the drilling head fitted on the moving piston are controlled by movement of the spool of the direction control valve which is actuated by the pilot valve and governed by the electromechanical stop as indicated in the figure. The rate of travel of the drill head i.e., the feed rate is governed by the throttle or metre controlling valve which is again controlled by a template like cam and a follower coupled with the spool of the throttle valve as shown in Fig. 4.7.11. To keep feed rate constant irrespective of the working force on the piston, a pressure reducing valve is provided prior to the throttle valve. The pressure reducing valve helps keep its exit pressure i.e., input pressure of the throttle valve fixed to a preset value irrespective of the input pressure of the pressure reducing valve which varies with the working load on the drill piston. Constant pressure difference keeps constant fluid flow rate through the throttle valve resulting constant feed rate irrespective of the cutting force.

Fig. 4.7.11 Circuitry and kinematic system of hydraulically driven machine tool





Fig.4.7.12 schematically shows the principle of typical hydraulic copying lathe.

Fig.4.7.12 Principle of hydraulic copy turning. Kinematic system and working principle of automatic lathes of

Single spindle automatic lathe

d autmatic lathe is also known as single

ction of

g ls feeding

g

The cross feed is controlled, under fixed longitudinal feed, hydraulically. When the stylus moves in the transverse direction slightly (by say x) due to slope or profile in the fixed template, the ports open enabling the high pressure fluid enter in the lower chamber. Since the piston is fixed, the sliding cylinder holding the cutting tool will start moving down. When the tool also retracts by x the ports get closed. This way the incremental or discrete motion of the stylus is replicated by the tool tip resulting true copying of the profile from the template to the job.

common use.

This general purpose and widely usespindle automatic screw cutting lathe (ssASCL) because such lathes were introduced aiming mainly mass production of fasteners having screw threads. Fig. 4.7.13 schematically shows the typical kinematic system of single spindleautomat. The major characteristic functions that are automatically accomplished in sequence and proper synchrony in such lathes are :

spindle speed change magnitude and direrotation bar feedin

transverse too turret indexing and travellin






Fig. 4.7.13 Typical kinematic system of single spindle automatic lathe.

Change of spindle speed Repetitive production in large volume and limted ranges of job tool materials and job diameter necessitate a small number of spindle speeds in automatic lathes unlike centre lathes. However, at least two speeds, high and low (for threading etc.) and provision of reversal of those speeds need to be provided in automatic lathes. Power and speed are transmitted from the motor to shaft I through belt-pulley and a speed gear box (SGB) if required as can be seen in Fig. 4.7.13. The two gear loosely mounted on shaft I are in mesh with two gears fixed on shaft II. Rotations are transmitted from shaft II to the spindle by two pairs of chain and sprockets as indicated in the kinematic diagram (Fig. 4.7.13). The two sprockets are loosely mounted on the spindle and simultaneously rotate at the same speed, low or high, but in opposite directions. The spindle is made to rotate at high or low speed and clockwise or anticlockwise by engaging the clutches on shaft I and the spindle respectively. The clutch is shifted by a lever and cylindrical cam which is rotated at the desired moment by one revolution only with the help of a single

Single revolution clutch

Cylindrical cam

barstock Finger collet

clutch

Trip dog

I

II

clutch

Cam Trip dog

turretTool slide

Cam follower

spindle collet




revolution clutch which is again triggered by a trip dog controlled by the amshaft as shown in the figure.

Bar feeding mechanism or feeding the barstock to a desired projection length after completing achining and parting a job, first the collet is opened by withdrawing the push rce by moving the taper ring outward by a lever automatically with the help f the cylindrical cam. Then the cam at the other end of the cylinder pushes e rod forward using the lever, a slide and finger collet. Next half of the tation of that cylindrical cam accomplishes clamping collet and return of the

nger collet by moving the levers in opposite direction. ere again, the cylindrical cam is rotated by only one revolution by actuating nother single revolution clutch at the proper moment by a trip dog as dicated in the figure.

Transverse tool feeds he radially moving cutting tools (upto five) are fed sequentially at preset mings and desired length and rate of travel by individual cams mounted on e cam shaft which rotates slowly with one rotation for one machining cycle

e., one product. ll the single revolution clutches are mounted on the auxiliary shaft which ositively roates at a constant speed of 120 rpm. Rotation is transmitted from at to the cam shaft through speed reduction and a feed gear box (FGB) to

ary the cam-shaft speed depending upon the cycle time for each job.

Feed motions of the axially fed cutting tools mounted on the turret he end points, length and rate of travel of the six tools on the turret are overned by a single plate cam having six lobes corresponding to the tools in e turret as shown in the figure. The rotational speed of that cam is kept

sam

Turret indexing mechanism he hexagonal turret is rotated (for indexing) by a Geneva mechanism where

l slots is driven by a revolving pin. Before

c

FmfoothrofiHain Ttithi.Apthv Tgth

e as that of the cam shaft. Ta Geneva disc having six radiastarting rotation, the locking pin is withdrawn by a cam lever mechanism shown in the diagram. The single rotation of the disc holding the indexing pin is derived from the auxiliary shaft with the help of another single revolution clutch as indicated Kinematic system and operating principle of Swiss type automatic

lathe The kinematic diagram of typical Swiss type automatic lathe is schematically shown in Fig. 4.7.14. Both the high speed of the spindle and the low speed of the cam shaft are derived from the motor as indicated in the diagram. All the cutting tools mounted on the transverse slides are travelled to desired depth and at desired feed rate by a set of plate cams mounted on the cam shaft. The headstock with the spindle having the barstock clamped in it is moved forward and





returned at desired feed rate by a set of plate cams mounted on the camshaft as shown.

Fig. 4.7.14 Kinematic system of Swiss type automatic lathe.

shifting the taper ring by a cam as shown Pushing the bar, against the last working tool, by a gravitational

he procedural steps to be followed in sequence for batch or lot production of

tools are : (a) Thorough study of the job to be produced: in respect of :

be produced

Feeding of the bar, after completion and parting of a job is done sequentially by

Opening the collet byforce

Collet clamping by return of the ring (iii) Process Planning And Tool Layout For Machining A Product In Semi-Automatic And Automatic Lathes. Ta job by machining in semi-automatic and automatic general purpose machine

volume of production, i.e., number of pieces of the specific job to

material and its properties size and shape surfaces to be machined required dimensions with tolerances and surface finish end use of the product





(b) Selection of machine tool (after studying the job): in respect of ;

type size precision kind and degree of automation

(c) Selection of blank (based on job and machine selected): in respect of; bar chucking or housing type preformed by; casting, forging, rolling etc. if bar type; cross section (circular, tubular, square, hexagon

etc.) nominal size based on largest dimensions and availability preformed by hot working or cold working

(d) Identification and listing of the elementary machining operations required, depending upon the product configuration

(e) Combine elementary machining operations as much as possible for saving time

(f) Sequence the operations (after combining) (g) Select cutting tools: in respect of;

type material size geometry

depending upon the machining operations (after combining) and work material

chart giving column-wise :

speed and feed for each operation

cutting fluid application;

the cutting tools and their location and mounting.

availability

(h) work scheduling or preparation of the instruction sheet or operation

description of the machining work to be done in sequence cutting tools : type and location length of travel of the tools

o yes or not required type of cutting fluid o

(i) Tool layout : schematically showing the type and configuration of

A typical tool layout for a particular job being machined in a single spindle automatic lathe is schematically shown in Fig. 4.7.15.





F a typical job in single automatic lathe.

(Iv) Case t Task (say onal headed mild steel

bolts , are to be produced by

uction capstan lathe is better)

Circular bar type job Common machinable material Simple machining operations required

ig. 4.7.15 Tool layout for

S udy : As An Example

) : 2500 pieces of hollow hexag, as shown in Fig. 4.7.16

mach i

:

in ng.

Machine tool selectedSingle spindle automatic lathe for

Lot production (for smaller volume of prod





Fig. 4.7.16 Shape and dimension of the specific job

Blank selected : Hot rolled hexagonal section mild steel bars for;

saving machining of the hexagonal head portion the hexagonal head is of standard size which is available not being precision job

tified and listed : Facing

dle portion Chamfering (3) bolt head

e diameter to 12 mm

Parting

job size reasonable for single spindle automatic Elementary machining operations iden

Centering Chamfering (1) front Chamfering (2) mid Rough turning (1) to make circular from hexagon Rough turning (2) to reduc Finish turning to 10 Drilling Grooving (forming) Thread cutting Initial parting





Combining elementary operations combining operations to be done by a compound tool in a

single travel from one tool position paralleling or overlapping operations to be done by different

tools moving in different directions.

he listed elementary operations can be combined and sequenced as follows

1 Rough turning (1), initial parting and rear chamfering (3) 2 Rough turning (to 12) and drilling and centering (for the next job) 3 Finish turning (10) 4 Spot facing and front chamfering (1) 5 Grooving and central chamfering (2) 6 Thread cutting 7 Parting

Scheduling operation chart indicating tools and tool positions and machining conditions.

= spindle s tting fluid turret face 1, RS = Rear slide, FS = front slide, VS =

TabSl. No.

S L CF

T:

NH

peed (rpm), s = feed (mm/rev), L = tool travel, CF = cuT (1) = hexagonal

vertical slide le 1 : Scheduling; operation chart

Operation Tool Tool N position

1 d

- - N Stop stock & bar Stop HT (1) - fee

2 Rough turning (1) Turning tool

Parting tool

HT(2) 640 0.10

30 6

Y Y Initial parting Formed RS 0.05

Chamfering (3) 3 )

iln

Turning tool HT(3)

640

0.10

50

Y

Rough parting (2Dr ling (6) Drill ce tering

]

4 i l HT(4) 640 0.05 25 Y Fin sh turning Turning too]

5 oa

5 5 Y Sp t facing Compound HT(5) 640 0.0Ch mfering (1) tool

6 o tool FS 640 0.05 10 Y Gr oving Form Chamfering (2)

] 7 die HT(6) 56 2 20 Y Threading Solid

] 8 Parting tool VS 640 0.05 12 Y Parting





The possproduct is sch

for machining the given job indl matic lathe

Tool layout ible tool layout made based on the scheduling made for the

ematically shown in Fig. 4.7.17.

Fig. 4.7.17 Tool layout in s sp ingle e auto





Dr.NNCE MECH/IV SEM MFT Lab-II LM

1

ME2258- MANUFACTURING TECHNOLOGY-II LABORATORY MANUAL

FOR IV SEMESTER MECHANICAL (FOR PRIVATE CIRCULATION ONLY)

ANNA UNIVERSITY CHENNAI

DEPARTMENT OF MECHANICAL ENGINEERING

DR. NAVALAR NEDUNCHEZHIYAN COLLEGE OF ENGINEERING THOLUDUR 606 303, CUDDALORE DISTRICT





2

LIST OF EQUIPMENTS 1. Centre Lathe with accessories 2 2. Turret and capstan lathes 2 3. Horizontal milling machine 1 4. Vertical milling machine 1 5. Surface grinding machine 1 6. Cylindrical grinding machine 1 7. Shaper 2 8. Slotter 1 9. Planner 1 10. Radial drilling machine 1 11. Tool dynamometer 1 12. Gear hobbing machine 1 13. Tool makers microscope 1

UNIVERSITY PRACTICAL EXAMINATION Allotment of Marks

Internal Assessment = 20 marks Practical Examination = 80 marks Total =100 marks

INTERNAL ASSESSMENT [20 Marks] Staff should maintain the assessment Register and the Head of the Department should monitor it.

SPLIT UP OF INTERNAL MARKS Observation = 3 marks Record Note = 7 marks Model Exam = 5 marks Attendance = 5 marks _________

Total = 20 marks ___________

UNIVERSITY EXAMINATION(80 Marks)

The examination will be conducted for 100 marks. Then the marks will be converted to 80 marks.

Split up of Practical Examination Marks

Aim and Procedure = 20 marks Job Finishing = 70 marks Viva -Voce = 10 marks ___________

Total = 100 marks ___________





3

GENERAL INSTRUCTIONS FOR LABORATORY CLASSES

Enter Lab with CLOSED FOOTWEAR

Boys should TUCK IN the shirts

Students should wear uniform only

LONG HAIR should be protected, let it not be loose especially near ROTATING MACHINERY.

Any other machines/ equipments should not be operated other than the

prescribed one for that day.

POWER SUPPLY to your test table should be obtained only through the LAB

TECHNICIAN Do not LEAN and do not be CLOSE to the rotating components.

TOOLS, APPARATUS & GUAGE Sets are to be returned before leaving the Lab.

HEADINGS & DETAILS should be neatly written 1. Aim of the experiment

2. Apparatus / Tools/ Instruments required 3. Procedure / Theory / Algorithm / Program 4. Model Calculations 5. Neat Diagram/ Flow charts 6. Specifications/ Designs details 7. Tabulation 8. Graph

9. Result/ Discussions Before doing the experiment, the student should get the circuit/ Program

approval by the

FACULTY-IN-CHARGE Experiment date should be written int the appropriate place After completing the experiments, the answer to the VIVA-VOCE Questions

should be neatly written in the workbook Be PATIENT, STEADY, SYSTEMATIC, & REGULAR





4

ME2258 MANUFACTURING TECHNOLOGY LABORATORY II L T P C 0 0 3 2 1. Two or more measurements in metal cutting Experiment [Example: Shear angle, cutting force, Tool Wear etc.]

2. One or more exercises in Shaper, Slotter, Planner, Drilling, Milling machines [Example: Round to Square, Dovetail in shaper, internal keyway cutting in Slotter, Round to square in Planner, Drilling, reaming and tapping in Drilling machine, Gear milling and key way milling in Milling machine]

3. Two or more exercises in Grinding/Abrasive machining [Example: Surface grinding, cylindrical grinding]

4. Two or more exercises in assembly of machined components for different fits. [Example: parts machined using lathes, shapers, drilling, milling and grinding machines etc.]

5. One or more exercises in Capstan or Turret lathes.

6. One or more exercises in Gear machining. [Example: Gear milling, Gear Hobbing etc.]





5

CONTENTS

S. No. L1ist of experiments

Page

N

o.

1 Making square from round rod using Shaper 15

2 Drilling, Tapping & Reaming in Radial drilling machine 18

3 Making dovetail from C.I. Block using Shaper 21

4 Making Internal key way cutting using Slotter 24

5 Making spur gear using Milling machine 27

6 Machining for press fit 29

7 Grinding to the required accuracy by Surface grinding 32

8 34

9 Machining for clearance fit 36

Beyond the syllabus

10 Making bevel gear 39

11 Straddle milling 42

12 Machine a cast iron bevel gear 45

Question bank 48

Signature of the Lab In charge (N.GANESH)





6

STUDY OF MILLING MACHINE AIM To study the working principle of milling machine.

MILLING MACHINE A milling machine is one of the most important machine tools. It remove metals from the work piece it fed against rotating cutting tool used. In milling machine it has multiple cutting edge which removes metal at a faster rate milling machine point of application in the production of gears and cutting tool.

TYPES OF MILLING MACHINE The milling machine classified as follows: 1)Column and knee type 2)Horizontal milling machine a)vertical milling machine b)Universal milling machine 3)Bed type milling machine 4)planer type

PRINCIPLE OPERATIONS AND PARTS OF A MILLING MACHINE The principle parts of the column and knee type milling machines are as follows: BASE It is a foundation of machine. It carries the column and give strength and rigidity to the machine it serves as the reservoir for cutting fluid. COLUMN It is the main supporting frame movement vertically on the base. KNEE It projects from column and sides up and down on the vertical guide ways of column in turns support the saddle and knee table. The vertical position of the knee can be adjusted by an elevating screw provided at the bottom of the knee. SADDLE It support the table and can be adjusted transversely on the guide ways provided on the top surface of the knee. These guide ways are exactly at 90o to the face of the column. TABLE It slides on the guide ways of saddle and travels longitudinally in a horizontal plane. It supports the work piece and other features on it. OVERHANGING ARM It is mounted on the top of the column in turn extend beyond the column face. ARBOR It may be considered as extension of the spindle.





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MILLING OPERATIONS: The different types of operations that can be performed in milling machine are given below:

Plain milling Angular milling Face and side milling Gang milling End milling Straddle milling.

PLAIN MILLING It is a method of producing flat surface. It is parallel to the axis of the cutter. It is held in the milling arbor. FACE AND SIDE MILLING It is a method of producing flat surface right angle to the axis of cutter and in turn in this method large flat surface can be obtained. GANG MILLING It is a method of milling by using two or more cutters arrangement together on one arbor. It is used the similar pieces must be made. ANGULAR MILLING It is a method if producing a flat surface at an angle to the axis of the cutter. Angular surface are milled by tilting the spindle. END MILLING It is a method of milling slots keyway surface by end mills and also it is used in milling cutters. STRADDLE MILLING It is a method of milling to parallel slides at a work by employing to side milling.

SHAPER PRINCIPLE OF OPERATION: The shaper which is having a reciprocating type of machine tool with single point cutting tool used to produce flat surface. The flat surface may be horizontal, vertical or inclined. It has three important parts such as 1.Table, 2.Tool head, 3. Ram The tool head is fitted on the front on the ram while the job is rightly fixed on the table. The tool is mounted on the tool post or head. The ram reciprocates along with the tool to remove the metal in the forward stroke called as cutting stroke. The tool does not cut the metal in the return stroke called as idle stroke. Therefore one pass is nothing but the combination of one forward and return stroke or one cutting and one idle stroke. So we are in a position to reduce idle stroke time by increasing the speed of the return stroke. That is the speed of cutting stroke will be lower than the speed of the return stroke.





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CLASSIFICATION OF SHAPERS: Generally, shapers are classified as follows 1. According to the type of driving mechanism

a. crank drive type b. Whitworth driving mechanism type c. Hydraulic drive type

2. According to the position of ram a. Horizontal shaper b. Vertical shaper c. Travelling head shaper

3. According to the table design a. standard or plain shaper b. Universal shaper

4. According to the type of cutting stroke a. Push out type b. Draw cut type

SHAPER SPECIFICATIONS: Generally, the specifications of a typical shaper are listed below:

1. Maximum length of stroke. 2. Maximum crosswise movement of the table. 3. Maximum vertical adjustment of the table. 4. Type of driving mechanism 5. Power of the motor 6. Speed and feed available 7. Type of shaper-plain or universal 8. Floor space required 9. Total weight of the shaper. 10. Ratio of cutting stroke time to return stroke time.

UPRIGHT OR PILLAR DRILLING MACHINE Upright drilling machine is a higher capacity version of sensitive drilling machine. It is a stationary floor mounted drilling machine. It is used for medium sized work pieces having medium speed. The spindle head and the drive arrangement in this machine are similar to a sensitive drilling machine. BASE: It is a supporting member on which all the parts of the machine are mounted. It is generally made of cast iron.





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COLUMN: It is a vertical member mounted on the base and carries table, Spindle and pulley drive mechanism. It should be very strong to take the heavy cutting forces. It may be round type or box type.

TABLE: The worktable is attached to the column by means of clamping screw. It has T-slots on the surface to hold the work pieces. It can move vertically along the column and can be adjusted radially about the column.

SPINDLE HEAD AND DRIVE MECHANISM: The spindle head is mounted on the top of the vertical column. It is driven by a motor through belt and step cone drive.

RESULT: Thus the tools of Special Machines were studied in this experiment.





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Experiment Number: 1

Title of the exercise : Making Square from round rod using Shaper Date of the exercise :

OBJECTIVE OF THE EXEPERIMENT To generate a square from rounded on the given work piece in a shaper machine.

FACILITIES REQUIRED AND PROCEDURE a. Facilities/material required to do the exercise:

S.No. Facilities/Material required Quantity 1. Punching machine 1 2. Steel rule 1 3. Hammer 1 4. Shaper tool 1 5. Try Square 1

bProcedure for doing the exercise: Steps

1. The job was checked to the given dimensions. 2. The square was scribed in the outer circle of diameter of 50mm and

punching was done.

3. The job was attached in the vice of a shaper 4. The job was checked for perpendicular dimension. 5. Then the square from round was obtained in the shaper

6. The work piece was removed and burns are removed with accuracy was checked.





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c. Figure

d.Result Thus the square from round was performed on the given dimension in a shaper machine with the required dimensions.





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Viva questions

1. What are the specifications of shaper? Maximum length of the stroke, power of the motor, floor space required, total

weight of the shaper. 2. Define cutting stroke? The ram reciprocates along with the tool to remove the metal in the forward stroke called cutting stroke. 3. What are the types of shaper? Horizontal shaper, vertical shaper, travelling shaper. 4. What are the main components of shaper? Base, column, cross rail, table. 5. Why the time for forward stroke is greater than return stroke? The metal is removed in the forward stroke, but no metal is cut during the return stroke. So the time for forward stroke is high.





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Title of the exercise : Drilling, Tapping, and Reaming in Radial drilling machine Date of the exercise :

OBJECTIVE OF THE EXEPERIMENT To make drilling, tapping and Reaming in the given work piece for the

required dimensions.


S.No. Facilities/Material required Quantity 1. Steel rule 1 2. Flat file(rough and smooth) 1 3. Drill bit(8 mm, 10 mm, 10.5 mm) 1 4. Reaming tool 1 5. Try square 1

b.Procedure for doing the exercise: Steps

1. The work piece was fitted in the vice and filed to the required dimensions.

2. The squareness of the work piece was checked.

3. Drawing punches were made for various drills.

4. The job was fitted on the radial drilling machine. 5. The 20 mm ,10.5 mm,8 mm, 6.5 mm-drill bit were used for drilling in

the required place and drilling operation were made on the work piece.

6. Reaming was done on the 8 mm hole using the Reaming tool size of 8 mm diameter. And tapping was done on the 6.5 mm drill and 10.5 mm drill. The work piece was removed from the radial drilling machine.





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c. Figure

d.Result

Thus the given job was drilled, tapped and Reaming to the required dimensions.





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Viva questions:

1. What are the components in radial drilling? Base, column, radial arm, drill head. 2. What is meant by tapping? Tapping is the operation of cutting internal threads in hole by cutting tool . 3. What is meant by counter boring? The operation of enlarging of end of hole cylindrically is known as counter boring. 4. What is meant by counter sinking? The operation of making a cone shaped enlargement of end a hole known as counter sinking. 5. What are the specifications of radial drilling machine?

Maximum size of drill head, Maximum spindle travelling, Power input of the machine(H.P), Floor space required m2 .





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Title of the exercise : Dove tail machining in shaper Date of the exercise :

OBJECTIVE OF THE EXEPERIMENT To perform a dove tail fitting on the given work piece by shaper machine.


S.No. Facilities/Material required Quantity 1. Steel rule 1 2. Scriber 1 3. Dot punch 1 4. Try square 1 5. Parting tool 1

b.Procedure for doing the exercise: Steps

1. Initially the given work piece is checked for its dimensions.

2. The dove tail surfaces are marked using scriber to given dimensions, then punched.

3. The job is fixed on a vice of the shaper to name external dove tail. 4. The vertical slide of the tool head is swiveled to the required angle

from vertical position.

5. The apron is further swiveled away from the work so that the tool will clear the work during return stroke.

6. The angular down feed is given to the required depth of cut and length of stroke is adjusted.

7. The above procedure is respected to obtain an internal dove tail part.

8. Then the work piece is removed and assembled for dove tail fit.





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c. Figure

d. Result:

Thus the dove tail [internal and external] part were made to the given dimensions and assembled to obtain dove tail fit assembly.





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Viva questions:

1. What are the specifications of shaper? Maximum length of the stroke, power of the motor, floor space required, total

weight of the shaper. 2. Define cutting stroke? The ram reciprocates along with the tool to remove the metal in the forward stroke called cutting stroke. 3. What are the types of shaper? Horizontal shaper, vertical shaper, travelling shaper. 4. What are the main components of shaper? Base, column, cross rail, table. 5. Why the time for forward stroke is greater than return stroke? The metal is removed in the forward stroke, but no metal is cut during the return stroke. So the time for forward stroke is high.





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Title of the exercise : Internal key way cutting in slotter Date of the exercise :

OBJECTIVE OF THE EXEPERIMENT To cut Internal key to the required dimensions in slotting machine to

accommodate key.


S.No. Facilities/Material required Quantity 1. Steel rule 1 2. Tipped tool 1 3. Scriber 1 4. Dot punch 1 5. Anvil 1 6. Surface gauge 1 7. Steel rule 1

b. Procedure for doing the exercise: Steps

1. The dimensions of the given work piece are checked as per the requirements.

2. Key and key way dimensions in proportionate to shaft diameter found.

3. Key way dimensions are marked over the shaft then permanent mark are made using dot punch.

4. Key way is machined in slotter machine to the required dimensions.





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c. Figure

d.Result: Thus the internal key way to the required dimension is cut in slotter.





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Viva questions:

1. Write any six specifications in slotter machine? Maximum stroke length, Diameter of rotary table, Type of drive used, Power rating motor, Net weight of machine, Floor area required.

2. What are the uses of slotter? Key way, Bit tool, Heavy tool holders.

3. Why the time for forward stroke is greater than the return stroke? In slotter, down stroke is the cutting stroke. The return stroke is idle. To reduce the idle return time, quick return mechanism is used.

4. What is the difference between shaper and slotter? Sl.No Shaper Slotter

1. Rotary table along with tools will remove. Slides will remove to perform slotting.

2. Vertical shaper is not fixed in the vertical plane. Slotter is fixed in the vertical plane.

5. What are the main components in slotting machine? Base, Column, Saddle, Rotary table, Ram and tool head.





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Title of the exercise : Spur Gear milling Date of the exercise :

OBJECTIVE OF THE EXEPERIMENT To perform a spur gear milling operation in milling machine.


S.No. Facilities/Material required Quantity 1. Steel rule 1 2. Milling cutter 1 3. Spanner 1 4. Mandrel 1 5. Dog carrier 1


1. The raw blank is selected with reference to the number of teeth to be cut.

2. Indexing number is calculated to the position of the blank.

3. Gear blank is mounted on mandrel in milling machine.

4. Centering of the blank is done by upward and cross feed.

5. The depth of the cut is calculated for the given module.

c. Figure





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d. Result:

Thus the spur gear cutting is performed in a milling machine.

Viva questions:

1. What are the main components in milling machine? Base, column, knee, saddle, table. 2. Write any six specifications in milling machine? The table length and width, power of driving motor, spindle nose taper size, type of milling machine, floor space and net weight. 3. What are the types of milling machine? Plain milling machine, vertical milling machine, universal milling machine, simplex milling machine, triplex milling machine. 4. What are the types of milling cutter?

Plain milling cutter, slide milling cutter, arbor cutters, shank cutters, face cutters. 5. What is the purpose of indexing head? The work piece held between centre of head stock and tail stock. Short work pieces are held in chuck fitted to head stock spindle.





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Title of the exercise : Machining for press fit Date of the exercise :

OBJECTIVE OF THE EXEPERIMENT To perform a machining operation for press fit in lathe machine.


S.No. Facilities/Material required Quantity 1. HSS Single point cutting tool 1 2. Vernier caliper 1 3. Steel rule 1

4. Chuck key 1 5. Tool post key 1 6. Drill bit socket 1


1. The given work piece is cut into two pieces to make an assembly with chuck key for its dimensions.

2. The end is faced and chucked for the centering of the tool.

3. The cutting tool is tighted by 30 for facing operation.

4. The step turning operation is repeated in the shaft to get accurate dimension by giving the gradual depth of cut and feeds,

5. The dimensions are checked by using the vernier caliper as per the specifications.

6. The above procedure is repeated with drill bit of 14 mm dia.





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c. Figure

d. Result: Thus the job was finished and checked for assembly.





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Viva questions:

1. What is meant by lathe? Lathe is a machine which removes the metal from a piece of work to the required shape and size. 2. Write any six specifications in lathe machine? The length of bed, swing over bed, swing over the cross slide, width of bed, spindle bore, spindle speed. 3. What are the main operations in lathe? Turning, Facing, Forming, Reaming, chamfering, Boring, Knurling. 4. Why lathe bed is made up of cast iron? To improve high strength. 5. What are the components of a lathe? Bed, head stock, tail stock, carriage, feed mechanism.





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Title of the exercise : Grinding to the required accuracy by surface grinding Date of the exercise :

OBJECTIVE OF THE EXEPERIMENT To perform a grinding operation in surface grinding machine.


S.No. Facilities/Material required Quantity 1. Steel rule 1 2. Try square 1 3. Vernier caliper 1


1. The given work piece is taken and checked for its dimensions.

2. The job is placed on the grinding magnet at opened position. 3. Then each face is grinded to the required accuracy by constant speed.

4. The job is removed from the required accuracy. It is checked by using vernier caliper and squareness is checked by using trysquare.

c. Figure





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d. Result: Thus the square section is grinded to the required accuracy in grinding machine.

Viva questions:

1. What is meant by surface grinding? Surface grinding machines are useful to produce and finish flat and plane surface. 2. What are the types of grinding machines? Transverse grinding, Plunger grinding. 3. How the grinding wheel is made? It is made up of abrasive material. 4. What is the purpose of magnetic chuck? Magnetic chuck is one type work holding devices. The chucks get magnetic power from electro magnet.





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Title of the exercise : Date of the exercise :

OBJECTIVE OF THE EXEPERIMENT To perform a cylindrical job using cylindrical grinding machine. FACILITIES REQUIRED AND PROCEDURE

a. Facilities/material required to do the exercise: S.No. Facilities/Material required Quantity

1. Steel rule 1 2. Vernier caliper 1 3. Outside caliper 1

4. Surface plate 1



2. The work piece is fired in between the live and dead centre and is rotated.

3. Machining is done by the movement of grinding wheel head into the work piece.

4. Remove the job and check its dimensional accuracy.

c. Figure





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d. Result: Thus the cylindrical job was done to the required accuracy in a cylindrical grinding machine.

Viva questions:

1. What is meant by surface grinding? Surface grinding machines are useful to produce and finish flat and plane surface. 2. What are the types of grinding machines? Transverse grinding, Plunger grinding. 3. How the grinding wheel is made? It is made up of abrasive material. 4. What is the purpose of magnetic chuck? Magnetic chuck is one type work holding devices. The chucks get magnetic power from electro magnet.





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Title of the exercise : Machining for clearance Fit Date of the exercise :

OBJECTIVE OF THE EXEPERIMENT To perform a machining operation for clearance fit in lathe machine.


S.No. Facilities/Material required Quantity 1. HSS Single point cutting tool 1

2. Vernier caliper 1

3. Steel rule 1 4. Chuck key 1 5. Drill bit socket 1 6. Surface gauge 1



2. In the shaft facing, turning, grooving, thread cutting operation were done to the required dimensions.

3. To obtain the required hole dimension pilot drill is properly fixed in the tail stock. The drill is moved along the axis of the job to carry out the drilling operation.

4. External thread cutting operation is carried out to the required TPI.

5. Finally the matching parts are fitted together to check assembly.





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c. Figure

d. Result: The jobs were finished to the required dimensions and assembly.





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Viva questions:

1. What is meant by lathe? Lathe is a machine which removes the metal from a piece of work to the required shape and size. 2. Write any six specifications in lathe machine? The length of bed, swing over bed, swing over the cross slide, width of bed, spindle bore, spindle speed. 3. What are the main operations in lathe? Turning, Facing, Forming, Reaming, chamfering, Boring, Knurling. 4. Why lathe bed is made up of cast iron? To improve high strength. 5. What are the components of a lathe? Bed, head stock, tail stock, carriage, feed mechanism.





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Title of the exercise : Making Bevel Gear Date of the exercise :

OBJECTIVE OF THE EXEPERIMENT To make a bevel gear in milling machine.


S.No. Facilities/Material required Quantity 1. Horizontal miller 1

2. Dividing head 1

3. 7/8 Arbor 1 4. 12 Pitch No.5 in volute gear cutter 1 5. Spacing collars 1


1. Mount the gear blank in the chuck on the dividing head.

2. Set the work to the cutter.

3. Take the first cut on the gear.

4. Finish cutting the teeth.

5. File the surfaces of the teeth.

c. Figure





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d. Result: Thus the bevel gear has make in a milling machine.





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Viva questions:







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Title of the exercise : Straddle milling Date of the exercise :

OBJECTIVE OF THE EXEPERIMENT To perform straddle milling in milling machine.



2. Dividing head 1


b. Procedure for doing the exercise:

Steps 1. Mount the gear blank in the chuck on the dividing head.









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c. Figure

Straddle Milling on Flatwork





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d. Result: Thus the straddle milling was performed in a milling machine.

Viva questions:







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Title of the exercise : Machine a cast iron bevel gear Date of the exercise :

OBJECTIVE OF THE EXEPERIMENT To machine a cast iron bevel gear in milling machine.



2. Dividing head 1



1. Mount the gear blank in the chuck on the dividing head.









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c. Figure





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d. Result: Thus the cast iron bevel gear is performed in a milling machine.

Viva questions:







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Question Bank 1. Making square from round rod using Shaper.

2. Drilling, Tapping &Counter sinking in radial drilling machine.

3. Making dovetail from round rod using shaper.

4. Making external key way cutting using slotter.

5. Making spur gear using milling machine.

6. Machining for press fit.

7. Grinding to the required accuracy by surface grinding.

8. Grinding to the required accuracy by cylindrical grinding.

9.

Machining for clearance fit.

Beyond the syllabus

10. Making bevel gear

11. Straddle milling

12. Machine a cast iron bevel gear




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