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DEVELOPMENTS IN
CNC MACHINES
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INTRODUCTION
CNC machines are the most standardized form ofmanufacturing the parts required to produce a productand The earliest CNC machines received codeinstructions through hard-wired controllers, whichmeant that the programming format could not be alteredin 1970 s and in this presentation we can seedevelopments in the tools, tool holding devices, work
holding devices, machining technique, and referencemeasurement etc
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ELEMENTS OF A NC SYSTEM
1. PROGRAMMING
2. TOOLING3. MACHINING
4. TOOL HOLDING
5. WORK HOLDING
6. REFERENCE MEASURING
7. IN PROCESS INSPECTION
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1. PROGRAMMING SYSTEMS
O0013
N0005 G53
N0010 T0404
N0020 G57 G00 X26.00 Z0.0 S500 M04N0030 G01 X-0.20 F100
G01 Linear interpolation (cutting)
X-0.20 Move only in x direction until you pass
the center by 0.1 mm (facing)F100 Set feed rate to 100 mm/min.
G00 Move rapidly away from work piece (no
cutting) to location x= 23.0 (11.50 from zero)
and z = 2.0.
APT Program Interpretation
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Automatic Part Programming: Developments
Software can generate program automatically from model
Make 3D model
Define Tool
CNC data
Simulate
cutting
Part program
Generation andMachining
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Automatic part programming and CNC
Very complex part shapesvery large NC program
NC controller memory may not handle HUGE part program
computer feeds few blocks ofNC program to controller
When almost all blocks executed,controller requests more blocks
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2. DEVELOPMENTS IN TOOLING
HSS TOOLS
POLY CRYSTALLINEDIAMOND TOOLSCEMENTED CARBIDE
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3. Conventional machining
Rough machining and semi finishing with thematerial in a soft i state (30-40hrc)
Heat treatment to obtain the required hardness (55-60hrc)
Electron discharge machining of particular zones ofthe die or of the matrix with very small rays or very
deep cavities Finishing of the remaining part of the die
Manual working to obtain the geometry and accuracyrequired manual polishing
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HIGH SPEED MACHINING
High speed rough machining and semi finishing withthe material in a solid state (30-40hrc)
Heat treatment to obtain required hardness (55-60hrc)
High speed finishing and super finishing with the toolsuitable for the specified material
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DEVELOPMENTS IN PROGRAMMING
Cutter dia: 63mm(3/4th used)
Depth of cut: 6mm
Spindle speed: 800 rpm Feed rate: 0.6 meters/min
Metal removal rate:170cm
3/min
Cutter dia: 63mm
(3/4th
used)
Depth of cut: 2mmSpindle speed: 2800 rpm
Feed rate: 3.8 meters/min
Metal removal rate:
243cm 3/min
High speed machiningConventional machining
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HSK : Hohl Shaft Kegel
(German)Means
Hollow Shank Taper
Using centrifugal force
principal and through
coolant holders
USED FOR SPEEDS 10000
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5. WORK HOLDING DEVICES
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DEVELOPMENTS IN WORK HOLDING
DEVICESHydraulic clampingPneumatic clamping
Vacuum clamping Magnetic clamping
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6. REFERENCE MEASURING
Dial gauge : Used for dialing the fixtures andtaking references of the work pieces
Touch probe : Used for takingReferences of the work pieces
Which directly enters the
reference values in the work
Coordinates of the machine
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7. INPROCESS INSPECTION
The touch probe can inspect the preprogrammed
dimensions in the machine itself and the dimensionalReport can be saved and even taken a Print out.
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NC MACHINE OF 1970s LATEST 5-AXIS CNC MACHINE
5-AXIS MACHINE AT DIFFERENT ORIENTATIONS