The presentation outlines the principles and advantages of CNC (Computer Numerical Control) machining, including classifications of CNC machining centers: vertical, horizontal, and universal. It highlights the innovative features of CNC turning and milling operations, detailing their programming structure and operational capabilities to produce precise parts efficiently. The document emphasizes the broader applications of CNC technology in modern manufacturing, showcasing the reduced lead time, lower costs, and improved accuracy associated with CNC processes.

1. Presentation on
Presented by
ACHYUTH P & TEAM
BOARD OF TECHNICAL EDUCATION, KARNATAKA
DEPARTMENT OF MECHANICAL ENGINEERING

2. Information source: Internet
Reference websites:
www.wikipedia.com/metal lathe
www.elearning.vtu.ac.in
Contents
 Classification of CNC Machining centres
 Special features of CNC Turning and Milling centres
 Configuration of CNC Machine control unit
 Advantages of CNC Turning and Milling centres
 Introduction to CNC, Turning and Milling operations

3. CNC:-It indicates “Computer and Numerically controlled”, It is defined as
“Automation of machine tools operated by precisely programmed commands with
computer playing important role of control ”
Milling:-Milling is a machining operation of producing flat, helical surfaces by
means of multiple cutting edged rotating tools called “Milling Cutters”. After the
advent of computer numerical control (CNC), milling machines evolved into
milling machining centers
CNC MILLING CENTER

4. Turning:-Turning is a machining process carried out in lathe machine, Where tool
moves parallel to axis of lathe and removes diameter of material.
CNC Lathes or Turning centres are rapidly replacing older producing lathes
CNC LATHE or CNC TURNING CENTER

5. CNC Machining centres are classified THREE types
1.A vertical machining centre (VMC) :-It has its spindle on a vertical axis relative to
the work table vertical machining centre is typically used for flat work that requires
tool access from top.
Milling Centre is a type of vertical machining centre
2.A horizontal machining centre (HMC):-It is used for cube shaped parts where tool
access can be best achieved on the sides of the cube.
Turning centre or Lathe is a type of Horizontal machining centre

6. 3. A universal machining centre (UMC) :-It has a work head that swivels its spindle
axis to any angle between horizontal and vertical making this a very flexible machine
tool.

7. CNC machining centers are usually designed with features to reduce non productive
time. The features are:
• Automatic tool changer :-
The tools are contained in a storage unit that is integrated with the machine tool.
When a cutter needs to be changed, the tool drum rotates to the proper position and an
automatic tool changer (ATC) operating under program control, exchanges the tool in
the spindle for the tool in the tool storage unit. Capacities of tool storage unit
commonly range from 16 to 80 cutting tools.
• Automatic work part positioner:-
Many horizontal and vertical machining centers have the capability to orient the work
part relative to the spindle. This is accomplished by means of a rotary table on which
work part is fixtured. The table can be oriented at any angle about a vertical axis to
permit the cutting tool to access almost the entire surface of the part in a single setup.

8. • Automatic pallet changer:-
Machining centers are often equipped with two (or more) separate pallets that can be
presented to the cutting tool using an automatic pallet changer. While machining is
performed with one pallet in position at the machine, the other pallet is in a safe
location away from the spindle. In this location, the operator can unload the finished
part and then fixture the raw work part for next cycle.

9. Memory
• ROM – Operating System
• RAM – Part Program
Central Processing Unit (CPU)
• Operator panel
• Tape reader
Machine tool controls
• Position control
• Spindle speed control
Sequence controls
• Coolant
• Fixture clamping
• Tool changer
System bus
Configuration of CNC machine control unit

10. CNC PROGRAMMING
CNC is the part program is a set of encoding information, giving
co-ordinates and other details to indicate how a tool should move
in a relation to a work piece in a machine should perform
desirable operation on the job.
CNC controls will be the program and execute the operations. The
program is prepared by co-ordinate values (XYZ) of the entire tool
path as suited to machine to complete the component and it also
contains the following basic information.
•Preparatory function (G code)
•Miscellaneous function (M code)
•Spindle speed (S)
•Feed rate (F)
•Tool number (T)

11. A part program contains a set of instruction which is written in
different block in the order of execution of different operations to
be performed on the job.
The part program contains a string of blocks which defined as the
sequence of operations. Each block contains a set of letters and
numerical values and followed by and charecters. The length of
the block is sufficient to accommodate 120 charecters and at the
each time.It can display 80 charecters. The block numbers will be
entred with adress N. The block numbers are freely selectable.
Structure of CNC part program

12. Structure of CNC part program

13. Preperatory functions (Or) G codes
These codes are assosiated with the axis movement of the machine. The G code starts
from zero and end upto 96.Normally the G codes will define path of the tool.

15. M- codes (Miscellaneous functions)
These codes are concerned with the operation of the machine tool.
Following are some of the important M-codes used in the part
programming.

16. CNC milling is a specific form of computer numerical controlled (CNC) machining.
Milling itself is a machining process similar to both drilling and cutting, and able to
achieve many of the operations performed by cutting and drilling machines. Like
drilling, milling uses a rotating cylindrical cutting tool. However, the cutter in a milling
machine is able to move along multiple axes, and can create a variety of shapes, slots and
holes. In addition, the work-piece is often moved across the milling tool in different
directions, unlike the single axis motion of a drill.
CNC milling devices are the most widely used type of CNC machine. Typically, they are
grouped by the number of axes on which they operate, which are labeled with various
letters. X and Y designate horizontal movement of the work-piece (forward-and-back
and side-to-side on a flat plane). Z represents vertical, or up-and-down, movement, while
W represents diagonal movement across a vertical plane. Most machines offer from 3 to
5 axes, providing performance along at least the X, Y and Z axes. Advanced machines,
such as 5-axis milling centers, require CAM programming for optimal performance due
to the incredibly complex geometries involved in the machining process. These devices
are extremely useful because they are able to produce shapes that would be nearly
impossible using manual tooling methods. Most CNC milling machines also integrate a
device for pumping cutting fluid to the cutting tool during machining.

17. Example of CNC Milling program

18. HOW IT WORKS ?
During CNC milling the computer translates the design into
instructions on how the drill needs to move to create the
shape.
Typically, the drill can move up down, or tilt at an angle, and
the table moves the part laterally.
For complex parts, the part may need to be rotated at some
point in the milling process.
Because the process is run by a computer, high resolutions,
and greater throughput are possible.

19. Materials used for CNC Milling Tools
 Aluminum Carbon Steel
 Stainless Steel
 Titanium
 Brass
 Copper
 Fiberglass
 Magnesium
 Plastic
 Plasticized Woods
 Foam

20. CNC TURNING
CNC Turning is manufacturing process in which a
round(cylindrical) material is held in a chuck and rotated
while a tool is fed to the piece to remove material to create
the desired shape. CNC lathes or turning centers have
tooling mounted on a turret which is computer-controlled.
CNC’s with “live” tooling

21. Example for CNC Turning program
Program
O 1005
[BILLET X32 Z60
G21 G98
G28 U0 W0
M06 T03
M03 S1200
G00 X32 Z1
G01 X5 F45
Z0
X10 Z-10
Z-15
G02 Z-25 R10 F25
G01 Z-30 F45
G03 X25 Z-37 R10 F25
G01 X25 Z-37 R10 F25
G01 Z-42 F45
X30 Z-45
Z-52 G28 U0 W0
M05
M02

22. How it works ?
 Designed mainly for machining shaft-type workpieces
supported by chuck and heavy-duty tailstock center
 On four-axis machines, two opposed turrets, mounted on
separate cross-slides
 One above and one below center line of work
 Balance cutting forces so extremely heavy cuts can be
taken on workpiece

23. Turning Center Equipments
 Steady rest
◦ Allow facing and threading on end of shafts
 Follower rest
◦ Used to support long, thin shafts
 Bar-feeding mechanism
◦ Permits machining of shafts and parts from bar stock
smaller than spindle through-hole
 Production part loader
◦ Can complete part changeover when individual precut
shafts machined

24.  Reduced lead time
 Elimination of operator errors
 Less Operator activity
 Less Labor Cost
 Longer Tool Life
 Elimination of special Jigs and Fixtures
 Flexibility in changes of product design
 Reduced inspection
 Reduced Scrap
 Accurate costing and scheduling