3. 1955 - US Air Force define a need to develop a machine tool capable of
machining complex and close tolerance aircraft parts.
1959 - MIT is the contractor and builds the machine for the project. MIT
announces Automatic Programmed Tools (APT) programming language
1960 - Direct Numerical Control (DNC). This eliminates paper tape and allows
programmers to send files directly to machine tools
1980’s - CNC machine is introduced. Unix and PC based systems
1997 - PC-Windows operating system is attached to cnc
8. Spindle in a vertical orientation.
VMCs are high-precision
Used for tight-tolerance
9.
10. Spindle in a horizontal orientation.
Horizontal orientation encourages
chips to fall away.
HMCs are high-precision
Used for tight-tolerance
11. Controlled by G and M codes.
These are number values and co-ordinates.
Each number or code is assigned to a particular operation.
Typed in manually to CAD by machine operators.
G & M codes are automatically generated by the computer
software.
12.
13. O - Program number
N - Sequence number
G - Preparatory function
X - X axis designation
Y - Y axis designation
Z - Z axis designation
R - Radius designation
F – Feed rate designation
S - Spindle speed designation
H - Tool length offset designation
D - Tool radius offset designation
T - Tool Designation
M - Miscellaneous function
15. M00 Program stop
M01 Optional program stop
M02 Program end
M03 Spindle on clockwise
M04 Spindle on counterclockwise
M05 Spindle stop
M06 Tool change
M08 Coolant on
M09 Coolant off
M10 Clamps on
M11 Clamps off
M30 Program stop, reset to start
20. • Posess hardness and strength at high
temperatures
• Able to withstand when heat is
generate
• Angle of the cutting face
• Flute width, number of flutes, teeth,
and margin size
21. Lubricating during cutting process
Cooling the workpiece at high cutting speeds
Improving tool life,
Improving surface finish
Flushing away chips from the cutting zone
Corrosion protection of the machined surface
22. STRAIGHT OILS -Non-emulsifiable and are used in machining operations in an
undiluted form they are composed of a petroleum oil , lubricants such as fats, vegetable oils
( BEST LUBRICATION )
SOLUBLE OILS -Contain no petroleum or mineral oil , composed of
alkaline inorganic and organic compounds ( BEST COOLING )
SEMISYNTHETIC FLUIDS- Emulsion when mixed with water
( LEAST EXPENSIVE )
SYNTHETIC FLUIDS-Combination of synthetic and soluble oil fluids
( COST AND HEAT TRANSFER PERFORMANCE )
23. High Accuracy e.g. Aircraft parts
Production rate is very high
Complex surfaces need to be machined
Flexibility in job change , automatic tool settings
More safe , higher productivity , better quality
Less paper work , faster prototype production
24. Costly setup
Skilled operators
Computers , Programming knowledge required
Maintenance is very difficult