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Computer Numerical Control and Programming
Dr. Mandeep Dhanda, PIED, PEC Chandigarh
1945
▫ First digital electronic computer ENIAC
1952
▫ MIT demonstrated First NC Machine in laboratory
NC Development
▫ Direct Numerical Control DNC
▫ Computer Numerical Control CNC
▫ Distributed Numerical Control DNC
▫ Flexible Manufacturing System FMS
▫ Computer Integrated Manufacturing CIM
2
History of NC
3
Numerical Control ?
A CONTROL Strategy
to
operate a machine tool
using
NUMBERS, LETTERS and SYMBOLS.
Control Strategy applied to various machine
tools.
• Lathe/Turning Centers
• Milling Centers – Simple/Complex 2-5 Axis
• Grinding
• EDM/Wire EDM
• Laser Cutting
• Tool Grinding
4
NC MachineTools
5
Applications of CNC
CNC Plasma Cutter CNC Engraving
CNC Electric Discharge Machining CNC Milling
6
Why CNC Machining ?
• For the parts
 having complex contours
 requiring very high accuracy and repeatability
 requiring many set-ups and/or the setups very
expensive
 subjected to frequent design changes, flexibility
• Reduction of Lead Time from Design to Mfg.
• Accurate machining of Complex surfaces/parts
• Excellent repeatability and Interchangeability
• Greater Machine utilization – scrap reduction
• Improved Productivity
• Quick Turn-around for design revisions, Prototyping
7
Advantages of NC Technology
8
Elements of NC tool operation
Data Processing Unit & Control loop unit
Function
• Reading Program
• Decoding
• Data Computation
• Axis Control Data Creation
• Data transfer to motors, relays
• Feedback control of axes
• Machine control functions
9
Elements of NC tool operation
BS 3635
• Motion Control
▫ Point to Point p
▫ Paraxial- Straight Line L
▫ Continuous Path / Contouring C
• Capabilities
▫ No. of Axes controlled Simultaneously
▫ Interpolation
 Linear, Circular, Helical, Parabolic
• Axis Definition
• Machine Configurations
▫ 2-5 axis
10
Classification of CNC system
11
Classification of NC system
NUMERICAL CONTROL
FINITE POSITIONING
CONTROLS
POINT TO POINT
SYSTEMS STRAIGHT CUT
SYSTEMS
CONTINUOUS PATH
SYSTEMS
CONTOURING
SYSTEMS
Ex. Drilling, Boring, Robotics Frame Milling, CNC Turning 2,3 axis contouring, SSM
• Moving at Maximum Feed rate from point to
point
• Accuracy of the destination is important but not
the path
• Drilling is a typical application
12
Point To Point - PTP
• Precise control of both the displacement and
velocity along the path (Both pos. and path
are important)
• Machining of profiles
• Uses Linear and Circular interpolators
13
Continuous Path Control
14
2. Point-to-point(P-T-P) control is applicable in case of
(a) CNC drilling machine
Short Quiz
(b) CNC milling machine (c) CNC lathe (d) None of these
1. There is a stepper motor rotating at 20 rpm and is connected with a table through gear box, lead screw-nut
connection as shown in Fig. 1. The table has single axis of motion and is developing a speed of 20 mm/min
along that axis due to motor rotation. The stepper motor covers one rotation in 200 steps and moves one
step per pulse of the pulse generator. The Basic length unit (BLU) of the drive is (motion of table per pulse of
pulse generator) ?
(a) 0.01mm (b) 0.05mm (c) 0.1mm (d) 0.005mm (e) None of these
3. CNC machining has the following main advantage over conventional automated machining
(a) Ability to employ higher
cutting speed, feed, doc
(b) Flexibility (c) Feedback control (d) None of these
4. An interpolator is definitely present in
(a) A CNC P-T-P control machine (b) A CNC P-T-P control machine with feedback
(c) A CNC continuous control machine (d) All CNC machines
20 rpm 20mm/min
1rev 1mm
1/200 rev 0.005mm
CNC Axes Nomenclature and
Configuration
15
16
CNC Axes Nomenclature
Linear : X, Y, Z (Primary)
U, V, W (Secondary)
P, Q, R (Tertiary)
Rotary : A, B, C
Control : Sequential
Simultaneous
Spindle axis is always Z
17
CNC Axes Designation
Vertical axis Milling machine CNC turning center
Rotating and Tilting Head (B, C)
18
Rotating and Tilting Table (A,C) Rotating Table, Tilting Head (A,C)
5 Axes CNC Machine Configuration
19
CNC 5 Axes Configuration
HMC with 5 axes-Rotary table
VMC with 5 axes-Tilting tool head
Turbine Blade - 5 axis CNC machining
https://www.youtube.com/watch?v=SNoj5XtpEa8
20
Video-5 axis CNC Machining
V8 Engine Block - 5 axis CNC machining
https://www.youtube.com/watch?v=wHstzxuryMk
CNC Programming
21
22
CNC Program
1. Reading drawing
2. Programming
3. Inputting Program
4. Manufacturing
From the drawing to the workpiece
23
Machine and Part Zero
• Each CNC machine has a built-in location that is called Machine zero.
• Before moving and cutting a block, the CNC machine needs to know where to start, the start
position is the part zero used in programming.
• This location acts as the origin from which all the other dimensions are calculated during the
program and it is usually located on the edge of a workpiece.
N010 G20 G40 G80 G90;
N020 S3000 M03;
• Program consists of BLOCKS.
• Each BLOCK has WORDS.
• Each WORD denotes ACTION.
• Program has to EXPLICITLY specify the
ACTION to be done by Tool/Machine.
24
CNC Program
M/c tool action:
• Feed the Tool. Start the Machine. Rotate Spindle.
• Clamp the Job.
• Start the Coolant.
• Stop the Machine.
25
G00
RAPID TRAVERSE
G01
LINEAR INTERPOLATION
(STRAIGHT LINE MOVEMENT)
G02
CIRCULAR INTERPOLATION
(CLOCKWISE)
G03
CIRCULAR
INTERPOLATION
(COUNTERCLOCKWISE)
CNC Command G/M code
(Deckel Maho, Inc.)
G – Preparatory code
26
M03
DIRECTION OF ROTATION
(CLOCKWISE)
M04
DIRECTION OF ROTATION
(COUNTERCLOCKWISE)
M06
TOOL CHANGE WITH
AUTOMATIC RETRACTION
M30
END OF PROGRAM
AND
RETURN TO BEGINNING
OF PROGRAM
Word Address Format
(Deckel Maho, Inc.)
M – Miscellaneous code
CNC Command G/M code
27
(Kelmar Associates)
Absolute/Incremental Programming
G90- Absolute Programming G91- Incremental Programming
28
Tool Path without Cutter Compensation Tool Path with Cutter Compensation
Cutter Compensation G41/42
G40- Cancel Cutter Compensation
Cutter Compensation: G41- Left
and G-42 Right
Part
Entry
Exit
Tool Path Stages
• Entry – RAMP ON
• Machining Profile
• Exit – RAMP OFF
29
When to start Compensation?
Point to Point (PTP) Programming
• Repetition – GOO, X, Y
• Modal Words - Create Compact Code
30
Programming
31
15 Holes
8 Dia, 5 Deep
100
100
200
300
Plate: 400 X 200 X 25 mm
25
25
Example (PTP)
32
-- -- -- --
N – G99 G81 X100 Y100 Z-5 R2 F50
N- M98 P300
N- X200 Y100
N- M98 P300
-- -- -- --
N- M30
:300
N10 G91 X25
N20 X-25 Y25
N30 X-25 Y-25
N40 X25 Y-25
N50 G90
N60 M99
25
25
CNC PTP Program, Subroutine
Absolute – G90
Incremental – G91
(X100 Y100)
100 100
100
33
% O0001
---Initialization------(G90 G21 G40 G80)
---Zero Setting------(G92 X0 Y0 Z0)
-Tool Selection(M06T1),Spindle On(M03)
G41 G01 X0 Y-40.0 F 300
Y250.0
X200.0
G02 Y0 R125.0;
G01 X-40.0
G40 G00 X-100.0 Y100.0
-Spindle Stop(M05),Return Home(G28)
---Program Stop – (M30)
Part Program- Contouring
34
• https://academy.titansofcnc.com/files/Fundamentals_of_CNC_Machining
• https://www.engr.uvic.ca/~mech410/CAM_references/CNC_Computer_Numerical_Control_Programmig_Basics
• CNC Programming Handbook (3rd edition) by Peter Smid
• Computer Numerical Control Simplified by Steve Krar and Arthur Gill
• CNC Programming Techniques by Peter Smid
• CNC Trade Secrets by James Harvey
• Programming of CNC Machines by Ken Evans
• Deckel Maho inc.
References

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CNC -Intro to mfg.pptx

  • 1. Computer Numerical Control and Programming Dr. Mandeep Dhanda, PIED, PEC Chandigarh
  • 2. 1945 ▫ First digital electronic computer ENIAC 1952 ▫ MIT demonstrated First NC Machine in laboratory NC Development ▫ Direct Numerical Control DNC ▫ Computer Numerical Control CNC ▫ Distributed Numerical Control DNC ▫ Flexible Manufacturing System FMS ▫ Computer Integrated Manufacturing CIM 2 History of NC
  • 3. 3 Numerical Control ? A CONTROL Strategy to operate a machine tool using NUMBERS, LETTERS and SYMBOLS.
  • 4. Control Strategy applied to various machine tools. • Lathe/Turning Centers • Milling Centers – Simple/Complex 2-5 Axis • Grinding • EDM/Wire EDM • Laser Cutting • Tool Grinding 4 NC MachineTools
  • 5. 5 Applications of CNC CNC Plasma Cutter CNC Engraving CNC Electric Discharge Machining CNC Milling
  • 6. 6 Why CNC Machining ? • For the parts  having complex contours  requiring very high accuracy and repeatability  requiring many set-ups and/or the setups very expensive  subjected to frequent design changes, flexibility
  • 7. • Reduction of Lead Time from Design to Mfg. • Accurate machining of Complex surfaces/parts • Excellent repeatability and Interchangeability • Greater Machine utilization – scrap reduction • Improved Productivity • Quick Turn-around for design revisions, Prototyping 7 Advantages of NC Technology
  • 8. 8 Elements of NC tool operation
  • 9. Data Processing Unit & Control loop unit Function • Reading Program • Decoding • Data Computation • Axis Control Data Creation • Data transfer to motors, relays • Feedback control of axes • Machine control functions 9 Elements of NC tool operation
  • 10. BS 3635 • Motion Control ▫ Point to Point p ▫ Paraxial- Straight Line L ▫ Continuous Path / Contouring C • Capabilities ▫ No. of Axes controlled Simultaneously ▫ Interpolation  Linear, Circular, Helical, Parabolic • Axis Definition • Machine Configurations ▫ 2-5 axis 10 Classification of CNC system
  • 11. 11 Classification of NC system NUMERICAL CONTROL FINITE POSITIONING CONTROLS POINT TO POINT SYSTEMS STRAIGHT CUT SYSTEMS CONTINUOUS PATH SYSTEMS CONTOURING SYSTEMS Ex. Drilling, Boring, Robotics Frame Milling, CNC Turning 2,3 axis contouring, SSM
  • 12. • Moving at Maximum Feed rate from point to point • Accuracy of the destination is important but not the path • Drilling is a typical application 12 Point To Point - PTP
  • 13. • Precise control of both the displacement and velocity along the path (Both pos. and path are important) • Machining of profiles • Uses Linear and Circular interpolators 13 Continuous Path Control
  • 14. 14 2. Point-to-point(P-T-P) control is applicable in case of (a) CNC drilling machine Short Quiz (b) CNC milling machine (c) CNC lathe (d) None of these 1. There is a stepper motor rotating at 20 rpm and is connected with a table through gear box, lead screw-nut connection as shown in Fig. 1. The table has single axis of motion and is developing a speed of 20 mm/min along that axis due to motor rotation. The stepper motor covers one rotation in 200 steps and moves one step per pulse of the pulse generator. The Basic length unit (BLU) of the drive is (motion of table per pulse of pulse generator) ? (a) 0.01mm (b) 0.05mm (c) 0.1mm (d) 0.005mm (e) None of these 3. CNC machining has the following main advantage over conventional automated machining (a) Ability to employ higher cutting speed, feed, doc (b) Flexibility (c) Feedback control (d) None of these 4. An interpolator is definitely present in (a) A CNC P-T-P control machine (b) A CNC P-T-P control machine with feedback (c) A CNC continuous control machine (d) All CNC machines 20 rpm 20mm/min 1rev 1mm 1/200 rev 0.005mm
  • 15. CNC Axes Nomenclature and Configuration 15
  • 16. 16 CNC Axes Nomenclature Linear : X, Y, Z (Primary) U, V, W (Secondary) P, Q, R (Tertiary) Rotary : A, B, C Control : Sequential Simultaneous Spindle axis is always Z
  • 17. 17 CNC Axes Designation Vertical axis Milling machine CNC turning center
  • 18. Rotating and Tilting Head (B, C) 18 Rotating and Tilting Table (A,C) Rotating Table, Tilting Head (A,C) 5 Axes CNC Machine Configuration
  • 19. 19 CNC 5 Axes Configuration HMC with 5 axes-Rotary table VMC with 5 axes-Tilting tool head
  • 20. Turbine Blade - 5 axis CNC machining https://www.youtube.com/watch?v=SNoj5XtpEa8 20 Video-5 axis CNC Machining V8 Engine Block - 5 axis CNC machining https://www.youtube.com/watch?v=wHstzxuryMk
  • 22. 22 CNC Program 1. Reading drawing 2. Programming 3. Inputting Program 4. Manufacturing From the drawing to the workpiece
  • 23. 23 Machine and Part Zero • Each CNC machine has a built-in location that is called Machine zero. • Before moving and cutting a block, the CNC machine needs to know where to start, the start position is the part zero used in programming. • This location acts as the origin from which all the other dimensions are calculated during the program and it is usually located on the edge of a workpiece.
  • 24. N010 G20 G40 G80 G90; N020 S3000 M03; • Program consists of BLOCKS. • Each BLOCK has WORDS. • Each WORD denotes ACTION. • Program has to EXPLICITLY specify the ACTION to be done by Tool/Machine. 24 CNC Program M/c tool action: • Feed the Tool. Start the Machine. Rotate Spindle. • Clamp the Job. • Start the Coolant. • Stop the Machine.
  • 25. 25 G00 RAPID TRAVERSE G01 LINEAR INTERPOLATION (STRAIGHT LINE MOVEMENT) G02 CIRCULAR INTERPOLATION (CLOCKWISE) G03 CIRCULAR INTERPOLATION (COUNTERCLOCKWISE) CNC Command G/M code (Deckel Maho, Inc.) G – Preparatory code
  • 26. 26 M03 DIRECTION OF ROTATION (CLOCKWISE) M04 DIRECTION OF ROTATION (COUNTERCLOCKWISE) M06 TOOL CHANGE WITH AUTOMATIC RETRACTION M30 END OF PROGRAM AND RETURN TO BEGINNING OF PROGRAM Word Address Format (Deckel Maho, Inc.) M – Miscellaneous code CNC Command G/M code
  • 27. 27 (Kelmar Associates) Absolute/Incremental Programming G90- Absolute Programming G91- Incremental Programming
  • 28. 28 Tool Path without Cutter Compensation Tool Path with Cutter Compensation Cutter Compensation G41/42 G40- Cancel Cutter Compensation Cutter Compensation: G41- Left and G-42 Right
  • 29. Part Entry Exit Tool Path Stages • Entry – RAMP ON • Machining Profile • Exit – RAMP OFF 29 When to start Compensation?
  • 30. Point to Point (PTP) Programming • Repetition – GOO, X, Y • Modal Words - Create Compact Code 30 Programming
  • 31. 31 15 Holes 8 Dia, 5 Deep 100 100 200 300 Plate: 400 X 200 X 25 mm 25 25 Example (PTP)
  • 32. 32 -- -- -- -- N – G99 G81 X100 Y100 Z-5 R2 F50 N- M98 P300 N- X200 Y100 N- M98 P300 -- -- -- -- N- M30 :300 N10 G91 X25 N20 X-25 Y25 N30 X-25 Y-25 N40 X25 Y-25 N50 G90 N60 M99 25 25 CNC PTP Program, Subroutine Absolute – G90 Incremental – G91 (X100 Y100) 100 100 100
  • 33. 33 % O0001 ---Initialization------(G90 G21 G40 G80) ---Zero Setting------(G92 X0 Y0 Z0) -Tool Selection(M06T1),Spindle On(M03) G41 G01 X0 Y-40.0 F 300 Y250.0 X200.0 G02 Y0 R125.0; G01 X-40.0 G40 G00 X-100.0 Y100.0 -Spindle Stop(M05),Return Home(G28) ---Program Stop – (M30) Part Program- Contouring
  • 34. 34 • https://academy.titansofcnc.com/files/Fundamentals_of_CNC_Machining • https://www.engr.uvic.ca/~mech410/CAM_references/CNC_Computer_Numerical_Control_Programmig_Basics • CNC Programming Handbook (3rd edition) by Peter Smid • Computer Numerical Control Simplified by Steve Krar and Arthur Gill • CNC Programming Techniques by Peter Smid • CNC Trade Secrets by James Harvey • Programming of CNC Machines by Ken Evans • Deckel Maho inc. References

Editor's Notes

  1. NC is a method of automation and nowadays computer is an integral part of that so CNC. NC is a CONTROL Strategy to operate a machine tool using NUMBERS, LETTERS and SYMBOLS. Remember NC is a Control Strategy to operate machine, NOT a machining method. NC machines CANNOT Think, Evaluate, Judge, Decide or Adapt like human beings.
  2. Control Strategy applied to various machine tools,
  3. Parts requiring very tight tolerances. Casting, molding parts need to machine the part and even additive not able to do
  4. MCU: Reading Program, Decoding, Parity Checking, Data Computation, Axis Control Data Creation BLU: Basic length unit
  5. An interpolator provides two functions: It calculates individual axis velocities to drive the tool along the programmed path at the given feed rate. Controler always takes the shortest path
  6. PTP: Position is more important, path is not Continuous/contouring: Both pos and path are important. An interpolator provides two functions: It calculates individual axis velocities to drive the tool along the programmed path at the given feed rate. Controler always takes the shortest path CNC axis system
  7. CNC M/c can be 2-3-4-5 axis. To study that we need to study their axis nomenclature. How they are designated. 3 primary linear axis ,3 additional rotational axis
  8. Here VMC is a 3axis milling m/c. Spindle axis is always Z even in cnc turning center
  9. Why 5 axis is more important why not 3?... Intricate shape where tool can’t reach or require more setup, if we need very high accuracy and complex contours..like here impeller /turbine blade 2 additional rotational axis to 3 linear will configure 5 axis.
  10. VMC- Vertical machining center, HMC- Horizontal machining center, spindle axis is always Z
  11. Part print analysis, process planning, CAM/manual program via USB derive or R123 cable, finally manufacture the part
  12. Each CNC machine has a built-in location that is called Machine zero. Before moving and cutting a block, the CNC machine needs to know where to start, the start position is the part zero used in programming. This location acts as the origin from which all the other dimensions are calculated during the program and it is usually located on the edge of a workpiece. Program consists of BLOCKS. Each BLOCK has WORDS. Each WORD denotes ACTION. Program has to EXPLICITLY specify the ACTION to be done by Tool/Machine
  13. Why G/M code used: Provide M/c tool action: Feed the Tool,Start the Machine, Rotate Spindle, Clamp the Job, Start the Coolant. Stop the Machine. G00: no cutting, fast travel G01: cutting with slow feed
  14. These are very basic G and M code. We need not to mug up, just understand their application, all will be provided during exams and lab course.
  15. Part Print Analysis: A detail study of Part drawings for the manufacturing of the part is called as Part Print Analysis
  16. CNC( PTP-point to point program): G99-Referencing, G80-Drilling canned cycle, R-referencing level over top of surface
  17. From a rectangular block to make/cut this profile, how can we do that? First analyze the part print, make the process plan and then start writing the program. CNC Contour Programming, Linear/Circular Interpolation used , Part Surface Programming,Tool Diameter Compensation Point to Point (PTP) Programming, Canned cycles, Subroutines, Tool Length Compensation