SEMINAR ON HIGH SPEED MACHINING (HSM)

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SEMINAR ONHIGH SPEED MACHINING (HSM)
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CONTENTS

• Introduction
• Definition of HSM
• Advantages
• Application areas
• Machining system
• Some recommended parameters
• Comparison
• Disadvantages
• Conclusion

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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

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DEFINITIONS

• 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.

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ADVANTAGES

• 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

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FEATURES EFFECTS
Reduced heat transfer in to the work piece Part accuracy
Reduction of cutting forces Part accuracy Surface quality
Increased cutting speed Stability of rotating cutting tool feed rate Increased material removal
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APPLICATION AREAS

• 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.

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MACHINING SYSTEM

• MACHINE TOOLS
• 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.

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DEMANDS ON THE MACHINE

• Spindle speed range lt40000 rpm
• Spindle power gt22 KW
• Programmable feed rate 40-60 m/min
• Rapid travels lt90 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

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CUTTING TOOLS

1. TiN and TiCN coated Carbide for materials with
   hardness less than 42 HRC
2. TiALN coated Carbide for materials with hardness
   42 HRC and above
3. For special applications like hard turning
   (HRC 60-65) PCBN is used
4. Cubic boron nitrite (CBN) and ceramic for cast
   iron
5. Poly crystalline diamonds (PCD) and Cermets are
   used for aluminum

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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

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• 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

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• 3. Surface finish
• Surface finish is depends upon cutting tool
  geometry, coating of the cutting tool, wear
  status of the cutting tool etc.

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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
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Comparison between speeds used in conventional
and high speed machining
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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
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HSM EDM
Material removal rate high Material removal rate is low
Dimensional tolerance 0.02 mm Dim tolerance 0.1- 0.2 mm
There is no need of making cutting tool according to the contour to be machined Cutting tool has to be made according to the contour to be machined
Comparison between HSM and EDM
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DISADVANTAGES

• 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

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CONCLUSIONS

• 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
• HSM is not necessarily high spindle speed
  machining. Many HSM applications are performed
  with moderate spindle speeds and large sized
  cutters
• 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.

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THANK YOU