Cnc t 100

CNC TRAIN MASTER LATHE
MODEL : CNC T – 100 (S)
SUBMITTED TO :- SUBMITTED BY :-
Prof. R.K. Mathur Rajeev Kumar Mandal Prof. O.P. Arora (H.O.D.) Kumar Gaurav DEPARTMENT OF MECHANICAL ENGINEERING FINAL YEAR (ME) BHAGWANT UNIVERSITY,AJMER RAJASTHAN

CAUTION
1. Proper earth connection for CNC system and machine.
User should be ensure proper earth connection to the
equipements.
2. Safety against input supply variation.
The machine operates successfully with an input voltage of three
Phase, 415 Volts +/- 10%, 50 Hz +/- 3% in case of variation in input
supply voltage beyond the range, user is advised to use a suitable
voltage stabilizing device like voltage stabilizer/ isolation
transformer etc.

INDEX
1.
INTRODUCTION
PAGE NO.
1.1
Develoment in metal cutting machine tools.
4
1.2
An insight to CNC machine.
4
1.3
CNC programming concept.
5
1.4
Need for training in CNC.
6
1.5
Advantages of CNC machines.
6
1.6
Objectives of CNC machine training.
6
1.7
Training method.
7
1.8
Knowledge level of trainee.
7
2.
SPECIFICATION AND FEATURES
2.1
Machine specifications.
8
2.2
CNC system features.
9
3.
MECHANICAL MACHINES DETAILS
3.1
Bed.
10
3.2
Saddle and cross slide.
10
3.3
Head stock.
10
3.4
Tail stock.
10
3.5
Tool turret.
10
3.6
AC servo motor and drives.
10
4.
OPERATING OF THE CNC SYSTEM
4.1
Putting machine in to operation.
11
4.2
Feed ON control ON.
11
4.3
Manual Movements.
11
4.4
Reference Point approach.
12
5.
PART PROGRAMMING
5.1
Coordinate system of CNC lathe.
13
5.2
Programming methods.
14
5.3
Preparatory function (G codes).
17
6.
TOOL SETTING
6.1
Work piece reference point setting.
18
6.2
Tool used.
18
7.
PRACTICAL EXERCISES
7.1
Description of standard cycles.
25
8.
Material needed for exercises.
Annexture-1
9.
Selection of working parameters for cutting in a lathe.
Annexture-2
10.
Electrical circuit diagrams.
28

1. INTRODUCTION:-
1.1 Development in metal cutting machine tools
The general purpose machine tools like lathe, milling, boring and grinding machine etc, were being operated manually until 1950 components needed in large numbers were catered by automats and special purpose machines. There were no machines available for catering special purpose machines. There were no machine available for catering to the need of batch production, where the higher productivity of special purpose machines is combined with the ease for job change over as in general purpose machine. If the general purpose machines could be operated automatically, and at higher speed, without the operator actually turning the hand wheels it would improve the productivity of these machines.
Such an automated machines is numerically controlled machine. Numerical control was developed in 1952 in USA and is commercially available since 1960s.In the last two decades rapid development and miniaturization in the field of electronics has made it possible to build controllers which can effectively control basic machine and also their peripheral devices reliably.
Production of CNC machine is increasing proportion of CNC machines among the total metal cutting machine tools also growing rapidly.
1.2 An insight to CNC machines
In manufacturer of part on machine tools, the work piece shape and dimension are achieved either by moving the tool against a rotating work piece or by moving the work piece against a rotating tool. The movement of tool/work piece is commanded manually through the help of hand operated controls through associated kinematics arrangements. This procedure is to be repeated to every piece produced. The dimension obtained by the operator setting have to be verified by measurements and suitable correction made. To produce component of high accuracy the operator must have high skill.
For complicated components the production cycle time be very large as each dimension must be measured and controlled. Components having special profiles which requires two or more slides to be moved simultaneously cannot be without special profile generation system. These factors are responsible for low production rates one conventional machines.
In a CNC machine, the slide (axes) movement are controlled by AC servo motors. The main objective is to be able to reach a particular point accurately at the required speed. The spindle speed is selectable according to needs of a particular job.

The selection and usage of the right tool for each of the machining operation as to be repetitively done each work piece by the machine operator on conventional machine. On NC machine, presenting the correct tool to the work piece is automatic by automatic indexing (as commanded) of multi-tool turret or automatic tool changer.
For achieving higher production rates, multiple activities of the machine such as speed changes, motions of various slides, presentation of the right tool should be made concurrent activities to the maximum extent. This would call for an ability for coordination and execution of multiple activities which is beyond the human capability. Electronics system use in the numerical control system can do this task with the required speed and precision with the development of the computer and microprocessors, the logic control functions are achieved through computers. Such systems are called CNC systems.
1.3 CNC Programming Concepts
CNC machines are controlled by CNC systems through the intermediate drive elements like motors, hydraulic actuators etc. in order to execute any particular task. CNC system required are technological like cutting speeds, feeds, dept of cut, type of tool and geometrical data like size and shope of the work piece to be cut.
The information input to such CNC system is to be in standard format such as
EIA-RS-274B for positioning and contouring control.
The programming format contains the letter code for each word with a special out number of digits for each numerical information. The letter codes includes the program the number, preparatory command, direction and distance to be moved for each axis, co-ordinates of the center of segments of circles for profile contouring, the feed rate , the tool number, spindle speed and other miscellaneous functions.
The general program format is :
Wkord sequence :
N…G…X…Y..Z..S..T..D…M..
N01G02X4Z8F42M2T6S4
The details of the format used for the machine is explained in the chapter.
5- part programming.
Also refer programming manual of siemens 802s CNC system supplied with machine.

1.4 Need for training in CNC
As explained in sections 2 and 3 CNC machines are fairly complex with many special functions added to those found on conventional machines to achieve better productivity through automation . these machines require instruction from the machine operator in a different medium then the conventional machines. To facilitate learning of operating CNC machines , it is essential to impart proper training and operating the machine with the prepared part program.
For preparing the part program, the geometrical information from the part drawing has to be converted to the program format. To get familiarization in program preparation, confidence in its correctness and operation of the CNC machine through th program ‘hand on training ‘ is required.
A full fledged CNC machine suitable for such a machine is very high making it consequently machine hour rates of such a machine is very high making it uneconomical for usage for training purpose. Any error by the learner in programming or operation of the machine will be expensive to correct as these could damage the machines apart from loss of production time. Trainer machines are built in such a way that there will be no damage to the machine even during the execution of faulty program. Thus the familiarly with CNC machining obtained by training machines will develop the confidence of the learner to a level where he can take up operation for machines.
1.5 ` Advantages of CNC machines:
1. High productivity for small/medium batch quantity manufacture.
2. Requires no special tool setting.
3. High repeatability and accuracy of work pieces.
4. Reduction in rejections
5. Can do complicated jobs not normally possible on conventional machines
6. Reduction in operator fatigue
7. Reduction in skill required for machining operations
8. Ease of product change over
9. Reduction in lead- time for staring production
1.6 Objectives of CNC machine training
1. To understand the operation of CNC control
2. To operate CNC machines based on the theoretical instructions obtained
3. Imparting the ability to write program for different parts, which are difficult to cut in conventional machines
4. To edit and execute these programs for different parts, which are difficult to cut in conventional machines
5. To reduce the difficulty for change over to production CNC machines
6. To understand the requirements of other features and peripherals needed for optimum machining.

1.4 Training method
Following sequential steps are generally to be followed to train person in
CNC machine operation:
1. Understanding specifications, features and functions of the machine
2. Familiarisation with the machine features and control for operation of the machine
3. Operating the machine through the CNC system
4. Familiarization with part programming methods
5. Took setting and tool selection
6. Practical exercises
1.8 Knowledge level of Trainee
The trainee should have the ability to read simple drawings, do simple arithmetical calculations. He must be able to select the cutting parameters such as speed, feed etc. for the machining operations.
The trainee should also be familiar with the use of a PC.

2. SPECIFICATIONS & FEATURES OF CNC T- 100 (S) LATHE
CNC T-100 Train Master Lathe is designed for training of operators, methods engineers in CNC turning technology, turning operations involving plain turning taper turning , threading cutting , radius turning can be performed on this lathe.
2.1 Machine Specifications
1. Height of centres. mm 100
2. Distance between centres. mm 310
3. Swing over bed. mm 150
4. Swing over cross slide mm 75
5. Traverse of cross slide mm 75
6. Max. turning Diameter mm 45
7. Max. turning length mm 150
8. Longitudinal traverse mm 180
HEAD STOCK
9. Hole through work spindle mm 16
10. Spindle taper MT
11. Type of drive AC variable
12. Speed range (step less) RPM 50 – 3200
13. Power Kw 0.75
TAIL STOCK
14. ` Spindle diameter mm 22
15. Spindle taper MT 1
16. Sleeve stroke mm 35
FEED RATE
17. Type of drive for both axis AC Servo motor
18. Rapid traverse rate mm/min 700
19. Programmable feed rate mm/min 0-0.700
CNC System
20. No. of axis 2
21. Type Siemens 80 2C
22. Weight of the machine (approx.) Kg. 250
23. Tool (Turret model, Pragati make) BTP 40
24. Tools stations Nos. 8
25. Turret indexing position - 8
26. Turning tool shank size mm 12*12

2.2 CNC system Features
 Table top model suitable for machining of non ferrous material,
however light cut of 0.2 mm on diameter without coolant can be
taken on mild steel.
 Step less AC drive.
 Antifriction preloaded high precision spindle bearing.
 Precision slide motion through for recirculating ball screw/ nut
arrangement for longitudinal and cross direction.
 Number of axes 2.
 Incremental and continuous JOG.
 Reference point approach.
 MDI/SINGLE BLOCK/AUTOMATIC execution.
 Axis homing.
 Feed hold.
 Feed rate over ride 0 to 120%.
 Standard G&M codes as per ISO.
 Linear and circular interpolation.
 Dwell time.
 Rapid feed rate 700mm/min.
 Thread cutting.
 Turning and threading cycles.
 Inch/metric mode of input.
 Feed programmable in per minutes and per revolution.
 Zero off sets.
 Tool nose radius compensation.
 Full screen editor.
 Cursor motions to selected block delete.
 Program handling function like dir.del.copy.remane.
 Block move, copy and delete.
 Graphic simulation.
 Block skip.
 MPG.
 A/C Panel

3. Mechanical Machine Details
The mechanical machine has the following:
1. Bed
2. Saddle and cross slide
3. Head stock
4. Tail stock
5. Tool turret
6. Axes drive system.
7. Spindle drive system.
3.1 BED
Bed is built with projected high quality cast iron and has V and flat
guideways & without side keeper plate. The head stock is mounted
on the left hand side of the bed. The bed is fixed on the base plate.
3.2 SADDLE AND CROSS SLIDE
The saddle is fitted over the bed guide ways using two keeper plates
lined with Turcite. The saddle is moved over the bed using the Z-axis
ball screw nut mechanism. The feed movement is obtained by a Stepper
motor and ball screw. It also houses the ball screw connected to the X
axis stepper motor through a timing belt. The cross slide carries the
tool turret on which the external turning tools and boring tools are mounted.
3.3 HEAD STOCK
The head stock contains the spindle of the machine. The spindle has a
MT2 taper and a adopter flange can be fixed for mounting three or four
jaw chucks.
3.3 TAIL STOCK
The tail stock can be fixed at any point along the bed guide ways using
a keeper plate. The tail stock has a sleeve with MT1 taper and can be
moved in or out using the small hand wheel. This can also be used for
mounting drills and centering bits.
3.5 TOOL TURRET
The auto tool turret having 4 internal and 4 external tools is mounted in
the cross sleeve. The turret is in directional drives in 24V DC motor.
3.6 MOTOR DRIVE
Stepper motor and drive are used in both the axes of siemens make.
Spindle drives with AC servo motor.

4. OPERATION OF THE SYSTEM
In the following pages the main operations are described. The operator is
advised to study earlier chapters regarding the location of the control and description of the control and be familiar with all controls to prepare for
this section.
To prepare part programme vis manual input mode observe guidelines of the programming and operating instructions of the CNC system manual supplied along with this manual.
Refer to appropriate operating manual of the CNC system supplied with the machine for the specific operation of the system control.
4.1 PUTTING MACHINE INTO OPERATION:
- Keep the emergency push button athe conrrol post pressed This - latches on its own and will remain closed. - Switch on the man incoming single phase supply. - Turn the mains switch at the control post to ON position(1S1). - Mains ON indication light on control post will be ON. - The emergency push button is now released and machine is ready for operation.
4.2 Feed ON/Control ON
Preconditions:
- Emergency push button EPM is not pressed.
- Light LTO is ON.
START:
- Press control ON push on machine control panel.
- Relay CRI will be ON.
- Message “NOT READY ON CNC SCREEN WILL GO AND AXES
DRIVE WILL BE ENABLES.”
4.3 Manual movement: a. Job mode Preconditions:
- Jog mode is selected on CRT
- Control/Feed ON
- Axes drives are healthy.
Note :- TOOL TURRET CAN BE INDEXED BY ONE POSITION BY PRESSING
TURRET INDEX KEY.

Start:
A)
- Select feed rate by feed over-ride switch.
- To move the X-axis slide towards inward,press - X key and
towards operator side,press + X key. - Rapid jog movement is effective by pressing two keys
simultaneously i.e. rapid movement key alongwith respective jog
movement key.
- To move Z axis slide towards left side, press –Z key and to move
- Towards right side,press +Z key.
B) Incremental mode : Preconditions ` - Select increment jog mode. - Select incremental mode on CRT as per requirement i.e. inc 1 or Inc 10 or inc 100. - Slide will move 0.001,0.01 and 0.100 mm respectively by selecting inc1, inc10 and 100. - Inc 1000 and inc 10000 are not effective.
C) Manual pulse generators MPG - Select MPG on CRT. - Manual pulse generator is provided for X and Z axis Slides depending upon selection and correction factor. Individual respective slide will move by the selected inc 1 or 10 per pulse desired direction.
4.4 Reference point approach : - Control/Feed ON - Drive for axes are enable i.e. CR1+ - Home mode selected on CRT, X and Z soft keys starts blinking. - Feed over-ride switch not at zero position. X-Axis - Select X axis by pressing +X key. - Slide X moves to reference position. Z-Axis - Select Z axis by pressing +Z key. - Slide Z mode to reference position, now X and Z axes are reference.
TOOL TURRET REFERENCE Press TURRET REFERENCE Key Turret moves to reference position.

PART PROGRAMMING
As explained in chapter 1.3 the part program provides the instructions to the CNC
control the execute the machine operations.The coordinate system of the machine has been explained is in the chapter.The programming methods program structure and explanation of each operating codes have also been provided.
5.1 Coordinate system of CNC lathe
The information “move the longitudinal slide in the head stock direction” is a very long one. besides, in each language, it would be different that’s why the traverse path movements in machine tools are described within the coordinate system. Coordinate system on a NC lathe is shown below.
Z-axis - Axis parallel to the turning axis
X- axis - Axis perpendicular to the turning axis
-Z movement - Movement of the longitudinal slide towards the
direction of the head stock.
+Z movement - Movement of the longitudinal slide away from
the head stock.
-X movement - Movement of the cross slide towards the spindle
axis.
+X movement - Movement of the cross slide away from the spindle
axis.

5.2 Programming methods
There are two method to describe the path of motion in a CNC machine:
1.Absolute programming method.
2.Incremental programming method.
In absolute programming method,the next point on the work piece is Taken as a reference or zero point and all the other dimensions are represented with respect to that point.
In incremental programming method,the next point dimension in each block is referred with respect to the final point on the previous block.
The system of dimensioning in each method is shown in the Illustrations.
ABSOLUTE SYSTEM OF DIMENSIONING
INCREMENTAL SYSTEM OF DIMENSIONING

Programming method comparison
Absolute system Incremental system
The path information given to the turning The zero reference point for Tools is always calculated from a definite each path information is the Starting point. Current position of the tool Itself.
Path X Z Path X Z
A -3 0 A -3 0
B -3 -2.5 B 0 2.5
C -2 -2.5 C 1 0
D -2 -4 D 0 -1.5
E 0 -0 E 2 -2
Only point 0 is the reference Point 0,1,2,3,4 are all new reference point.

Absolute system Incremental system
If you have to change the position of a If you have to change position Point all other points still remain of one point,all the Following Unchanged. Ones will have to be changed As well.
Point 1 has to be changed to point 1 since point 1 was changed, the The description for point 2 and 3 description for point 2&3 also Changes. remains unchanged.
Path X Z Path X Z
A -1 -1 A -1 1
B -1 -2.5 B 0 1.5
C 0 -2.5 C 1 0
D -1.5 -0.5 D -1.5 -0.5
E 0 -2.5 E 1 0
Effective until cancelled by G00,G01

5.3 PREPARATORY FUNCTION (G FUNCTION)
G code Table :
G CODE
FUNCTION
G00
Positioning (Rapid traverse)
G01
Linear interpolation (Feed)
G02
Circular interpolation CW
G03
Circular interpolation CCW
G04
Dwell time
G9
Non-model exact stop
G17
(Required for center drilling)
G18
Z/X Plane selection
G22
Radius input
G23
Diameter input
G25
Lower spindle speed limit
G26
Upper spindle speed limit
G40
Tool radius compensation off
G41
Tool radius compensation left of cotour
G42
Tool radius compensation right of cotour
G53
Non-model suppression of settable of zero offset
G54
1st settable zero offset
G55
2nd settable zero offset
G56
3rd settable zero offset
G57
4th settable zero offset
G60
Exact positioning
G64
Contineous path mode
G70
Dimensions in inches
G71
Dimensions in metric values
G74
Reference point approach
G75
Fixed point approach
G90
Absolute dimensions
G91
Incremental dimensions
G94
Feed rate F in mm/min.
G95
Feed rate F in mm/rev of spindle
G96
Constant cutting speed for turning on (F in mm/rev,S in m/min)
G97
Constant cutting speed of turning off
G158
Programmable offset
G450
Transition circle
G451
Point of intersection
G500
Settable zero offset off
G601
Exact positioning window fine for G60,G9
G602
Exact positioning window coarse for G60,G9

6. Tool Setting
6.1 Work piece reference point setting
Switch the spindle on set the spindle RPM ` By joggong the X and Z axis bring the tool to the desired position (i.e. when the tool just scratches the work piece). Using PRESET mode preset X and Z axis value to zero.
6.2 Tool used on this lathe
Depending upon the operation and configuration of the components
Following tools can be used on the machine.
1. Right hand side tool
2. Left hand side tool
3. Neutral tool
4. External threading tool
5. External grooving tool
6. Parting off tool
7. Internal threading tool
8. Boring tool
The detailed application of the above tools is given in the following
pages.

THE RIGHT HAND SIDE TOOL
Dimensions and applications
Shape turning
Beta(β) Must not be bigger than 50 deg.
Otherwise there will be interference
and rubbing.
Clearance angle C=93 deg. Radius Turning
Longitudinal turning,facing
The depth of cut ‘a’ in the facing should Not be larger than 0.3 mm.

THE LEFT HAND SIDE TOOL
Shape turning
Γmust be atleast 2 deg. and β max is equal to 50 deg.
Longitudinal turning facing
The depth of cut ‘a’ within facing should not exceed 0.3 mm.

THE NEUTRAL TOOL
Longitudinal and angle turning The max. depth of cut ‘a’ when turning must not be larger than 0.3 mm,with the turning angle of 70 deg. Turning of partial radius turning
The angle of the arc must not be largest than 70 deg.
Max. angle = 70.5 deg. Clearance angle = 2.5 deg.

EXTERNAL THREADING TOOL
For external threads with pitches from 0.5-1.5 mm index able tips are used.
Plunge Cutting Tool Width of the tips = 1.1 mm Max. depth of cut = 2.1 mm

PARTING – OFF TOOL HSS
INTERNAL THREADING TOOL
Internal threading can be done on jobs with minor thread diameter of 20 mm or more. Inexorable tips of pitches from 0.5 to 1 mm can be used.
Note : Alternatively, brazed internal threading tools may be used.

INSIDE TURNING TOOL
Inside turning (Boring) can be performed on jobs with internal diameter more than 16 mm.
Dimensions : Max. clearance angle when turning inwards = 90 deg. Max. depth of cut (Facing) is 0.3 mm.

7. Practical Exercises
Please refer chapter 9 of programming manual of SIEMENS 802S CNC
System supplied with the machine, containing following standards cycles:
7-1 Drilling, Spot-facing. - LCYC82
7-2 Deep hole drilling - LCYC83
7-3 Tapping with compensation chuck. - LCYC840
7-4 Boring. - LCYC85
7-5 Recess. - LCYC93
7-6 Undercut (Forms E and F to DIN) - LCYC94
7-7 Stock removal with relief cuts. - LCYC95
7-8 Thread cutting. - LCYC97

Annexure – 1
Material needed for training
SL.
No.
Description
Specification
No. off
Remarks
1.
Raw material
A1 rod
IS D734-1975 Dsgn,22588
45*65mm & dia 45*30mm
2
2.
Raw material
Mild steel
IS 1732-1971
45*65mm
2
3.
Chuck
3 Jaw self centering chuck
1
4.
Tools
Rt. Hand turning tool with inserts
1
Lt. Hand turning tool with inserts
1
Neutral tirning tool with insert
1
Parting off tool
1
External thread cutting tool
1
Internal thread cutting tool
1
Boring tool with inserts
1
5.
Standard tools
Spanners 7*8,8*10,13*17 Allen key
3,4,5,6
1 set

Annexure – 2
Selection of working parameters for cutting in a lathe
1. Cutting speed (Vs)
Vs (M/min)= ( ) ( ) ⁄
d = Diameter of the work piece
s = Spindle speed (RPM)
Cutting speed to be used in this lathe
For turning : 150 to 200 M/min.
For parting off : 60 to 80 M/min.
2. Calculation of spindle speed
S(Revolution/min)= ( ) ⁄ ( )
3. Cutting of feed F
F (mm/min.)= S(Rev/Min.) * F (mm/Rev)
For normally used for turning : 0.02 to 0.1 mm/Rev.
For used for parting off : 0.01 to 0.02 mm/Rev.

10. Electrical circuit diagrams.

Cnc t 100

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