SEMINAR ON
HIGH SPEED MACHINING
(HSM)
CONTENTS
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Introduction
Definition of HSM
Advantages
Application areas
Machining system
Some recommended parameters
Comparison
Disadvantages
Conclusion
DEFINITION OF HSM
Carl Salomon assumes that
“At a certain cutting speed
which is 5-10 times
higher than in
conventional machining
the chip removal
temperature at the cutting
edge will start to
decrease”
DEFINITIONS
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High cutting speed machining
High rotational speed machining
High feed machining
High speed and feed machining
High productive machining
Finally,
“HSM is a powerful machining method that combines
high feed rates with high spindle speeds, specific
tools and specific tool motion.”
ADVANTAGES
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High material removal rate
High surface finish
Increased productivity
Possibility of machining of very thin walls
Reduction in lead times
Low cutting force
Cutting tool and work piece temperature are kept low
Connection time between the cutting edge and work piece is
short
It eliminates the need of coolant
Reduction of production process
FEATURES
Reduced heat
transfer in to the
work piece
Reduction of
cutting forces
Increased cutting
speed
EFFECTS
Part accuracy
Part accuracy
Surface quality
Stability of rotating
cutting tool feed rate
Increased material
removal
APPLICATION AREAS
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Industry which deals with the machining of Al to
produce automotive components, small computer
parts or medical devices
Aircraft industry involves machining of Al often
with thin walls
Die mould industry which requires dealing with
finishing of hard materials .
Used to machine such parts as die casting dies,
forging dies, injection moulds and blow moulds,
milling of electrodes in graphite and copper,
modeling and prototyping of dies and moulds.
MACHINING SYSTEM
MACHINE TOOLS
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3-axis horizontal and vertical milling machines
CNC 4-axis milling machine offers the option of
tilting the milling cutters to improve the cutting
conditions
5-axis machine with inter changeable spindle units
allow to rough, semi finish and finish with a single
set up.
DEMANDS ON THE MACHINE
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Spindle speed range <=40000 rpm
Spindle power >22 KW
Programmable feed rate 40-60 m/min
Rapid travels <90 m/min
Block processing speed 1-20 ms
High thermal stability and rigidity in spindle
Air blast/coolant through spindle
Advanced look ahead function in the CNC
CUTTING TOOLS
1.
2.
3.
4.
5.
TiN and TiCN coated Carbide for materials with
hardness less than 42 HRC
TiALN coated Carbide for materials with hardness
42 HRC and above
For special applications like hard turning
(HRC 60-65) PCBN is used
Cubic boron nitrite (CBN) and ceramic for cast iron
Poly crystalline diamonds (PCD) and Cermets are
used for aluminum
RECOMMENDED PARAMETERS
1.True cutting speed
As the speed is dependent on both spindle speed
and diameter of tools HSM should be defined
as “true cutting speed” above a certain level
2.Material removal rate
Material removal rate,
Q = (ap* ae * vf)/1000 cm3/min
where ap = vertical dist from tool tip to the
reference point mm
ae = step over distance mm
vf = feed speed mm/min
3. Surface finish
Surface finish is depends upon cutting tool
geometry, coating of the cutting tool, wear
status of the cutting tool etc.
COMPARISONS
Conventional machine
High speed machine
Max speed 600 m/min
Speed starts at 600 m/min
Max feed ~40 ipm
Feed starts at 100 ipm
Require high levels
coolant
With coolant ,feed rate
can go more than 2000
ipm
No need for coolant for
low feed rate
Between conventional and high speed machines
Comparison between speeds used in conventional and high speed
machining
Conventional
HSM
The contact time between
tool and work is large
Contact time is short
Less accurate work piece
More accurate work piece
Cutting force is large
Cutting force is low
Low surface finish
High surface finish
Material removal rate is low
Material removal rate is
high
Cutting fluid is required
Cutting fluid is not required
Comparison between convl and HSM process
HSM
EDM
Material removal rate
high
Material removal rate is
low
Dimensional tolerance
0.02 mm
Dim tolerance
0.1- 0.2 mm
Cutting tool has to be
made according to the
contour to be machined
There is no need of
making cutting tool
according to the contour
to be machined
Comparison between HSM and EDM
DISADVANTAGES
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Need for expensive and special machine tools
with advanced spindle and controllers
Excessive tool wear
Good work and process planning necessary
It can be difficult to find and recruit advanced
staff
CONCLUSIONS
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HSM is not simply high cutting speed .It should be
regarded as a process where the operations are
performed with very specific methods and precision
equipment
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HSM is not necessarily high spindle speed
machining. Many HSM applications are performed
with moderate spindle speeds and large sized cutters
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HSM is performed in finishing in hardened steel with
high speeds and high feeds often with 4-6 times
conventional cutting speeds
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HSM is high productive machining in small
sized components in roughing to finishing and
in finishing to super finishing in components
of all sizes.
Even though HSM is known for a long time,
the research are still being developed for
further improvement of quality and
optimization of cost.