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HIGH SPEED MACHINING HIGH SPEED MACHINING (HSM)(HSM)

CONTENTSCONTENTS

IntroductionIntroduction Definition of HSMDefinition of HSM AdvantagesAdvantages Application areasApplication areas Machining systemMachining system Some recommended parametersSome recommended parameters ComparisonComparison DisadvantagesDisadvantages ConclusionConclusion

DEFINITION OF HSMDEFINITION OF HSM

Carl Salomon assumes that Carl Salomon assumes that

“ “At a certain cutting speed At a certain cutting speed which is 5-10 times which is 5-10 times higher than in higher than in conventional machining conventional machining the chip removal the chip removal temperature at the cutting temperature at the cutting edge will start to edge will start to decrease”decrease”

DEFINITIONSDEFINITIONS

High cutting speed machiningHigh cutting speed machining High rotational speed machiningHigh rotational speed machining High feed machiningHigh feed machining High speed and feed machiningHigh speed and feed machining High productive machiningHigh productive machining

Finally,Finally, “ “HSM is a powerful machining method that combines HSM is a powerful machining method that combines

high feed rates with high spindle speeds, specific high feed rates with high spindle speeds, specific tools and specific tool motion.” tools and specific tool motion.”

ADVANTAGESADVANTAGES High material removal rateHigh material removal rate High surface finish High surface finish Increased productivityIncreased productivity Possibility of machining of very thin wallsPossibility of machining of very thin walls Reduction in lead timesReduction in lead times Low cutting forceLow cutting force Cutting tool and work piece temperature are kept lowCutting tool and work piece temperature are kept low Connection time between the cutting edge and work piece is Connection time between the cutting edge and work piece is

shortshort It eliminates the need of coolantIt eliminates the need of coolant Reduction of production processReduction of production process

FEATURESFEATURES EFFECTSEFFECTS

Reduced heat Reduced heat transfer in to the transfer in to the work piecework piece

Part accuracyPart accuracy

Reduction of Reduction of cutting forcescutting forces

Part accuracyPart accuracy

Surface qualitySurface quality

Increased cutting Increased cutting speedspeed

Stability of rotating Stability of rotating cutting tool feed rate cutting tool feed rate

Increased material Increased material removalremoval

APPLICATION AREASAPPLICATION AREAS Industry which deals with the machining of Al to Industry which deals with the machining of Al to

produce automotive components, small computer produce automotive components, small computer parts or medical devicesparts or medical devices

Aircraft industry involves machining of Al often Aircraft industry involves machining of Al often with thin wallswith thin walls

Die mould industry which requires dealing with Die mould industry which requires dealing with finishing of hard materials . finishing of hard materials .

Used to machine such parts as die casting dies, Used to machine such parts as die casting dies, forging dies, injection moulds and blow moulds, forging dies, injection moulds and blow moulds, milling of electrodes in graphite and copper, milling of electrodes in graphite and copper, modeling and prototyping of dies and moulds. modeling and prototyping of dies and moulds.

MACHINING SYSTEMMACHINING SYSTEM

MACHINE TOOLSMACHINE TOOLS 3-axis horizontal and vertical milling machines3-axis horizontal and vertical milling machines CNC 4-axis milling machine offers the option of CNC 4-axis milling machine offers the option of

tilting the milling cutters to improve the cutting tilting the milling cutters to improve the cutting conditionsconditions

5-axis machine with inter changeable spindle units 5-axis machine with inter changeable spindle units allow to rough, semi finish and finish with a single allow to rough, semi finish and finish with a single set up.set up.

DEMANDS ON THE MACHINEDEMANDS ON THE MACHINE

Spindle speed range <=40000 rpmSpindle speed range <=40000 rpm Spindle power >22 KWSpindle power >22 KW Programmable feed rate 40-60 m/minProgrammable feed rate 40-60 m/min Rapid travels <90 m/minRapid travels <90 m/min Block processing speed 1-20 msBlock processing speed 1-20 ms High thermal stability and rigidity in spindleHigh thermal stability and rigidity in spindle Air blast/coolant through spindleAir blast/coolant through spindle Advanced look ahead function in the CNCAdvanced look ahead function in the CNC

CUTTING TOOLSCUTTING TOOLS

1.1. TiN and TiCN coated Carbide for materials with TiN and TiCN coated Carbide for materials with hardness less than 42 HRChardness less than 42 HRC

2.2. TiALN coated Carbide for materials with hardness TiALN coated Carbide for materials with hardness 42 HRC and above42 HRC and above

3.3. For special applications like hard turning For special applications like hard turning (HRC 60-65) PCBN is used(HRC 60-65) PCBN is used

4.4. Cubic boron nitrite (CBN) and ceramic for cast ironCubic boron nitrite (CBN) and ceramic for cast iron

5.5. Poly crystalline diamonds (PCD) and Cermets are Poly crystalline diamonds (PCD) and Cermets are used for aluminumused for aluminum

RECOMMENDED PARAMETERSRECOMMENDED PARAMETERS

1.1.True cutting speedTrue cutting speed

As the speed is dependent on both spindle speed As the speed is dependent on both spindle speed and diameter of tools HSM should be defined and diameter of tools HSM should be defined as “true cutting speed” above a certain level as “true cutting speed” above a certain level

2.2.Material removal rateMaterial removal rate

Material removal rate, Material removal rate,

Q = (aQ = (app* a* ae e * v* vff)/1000 cm)/1000 cm33/min/min

where awhere app = vertical dist from tool tip to the = vertical dist from tool tip to the reference point mm reference point mm

aaee = step over distance mm = step over distance mm

vvff = feed speed mm/min = feed speed mm/min

3. 3. Surface finishSurface finish

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

COMPARISONSCOMPARISONS

Conventional machineConventional machine High speed machineHigh speed machine

Max speed 600 m/minMax speed 600 m/min Speed starts at 600 m/minSpeed starts at 600 m/min

Max feed ~40 ipmMax feed ~40 ipm Feed starts at 100 ipmFeed starts at 100 ipm

Require high levels Require high levels coolantcoolant

With coolant ,feed rate With coolant ,feed rate can go more than 2000 can go more than 2000 ipmipm

No need for coolant for No need for coolant for low feed ratelow feed rate

Between conventional and high speed machines

Comparison between speeds used in conventional and high speed machining

ConventionalConventional HSMHSM

The contact time between The contact time between tool and work is largetool and work is large

Contact time is shortContact time is short

Less accurate work pieceLess accurate work piece More accurate work pieceMore accurate work piece

Cutting force is largeCutting force is large Cutting force is lowCutting force is low

Low surface finishLow surface finish High surface finishHigh surface finish

Material removal rate is lowMaterial removal rate is low Material removal rate is Material removal rate is highhigh

Cutting fluid is required Cutting fluid is required Cutting fluid is not requiredCutting fluid is not required

Comparison between convl and HSM process

HSM HSM EDMEDM

Material removal rate Material removal rate highhigh

Material removal rate is Material removal rate is lowlow

Dimensional tolerance Dimensional tolerance 0.02 mm0.02 mm

Dim tolerance Dim tolerance

0.1- 0.2 mm0.1- 0.2 mm

There is no need of There is no need of making cutting tool making cutting tool according to the contour according to the contour to be machinedto be machined

Cutting tool has to be Cutting tool has to be made according to the made according to the contour to be machinedcontour to be machined

Comparison between HSM and EDM

DISADVANTAGESDISADVANTAGES

Need for expensive and special machine tools Need for expensive and special machine tools with advanced spindle and controllerswith advanced spindle and controllers

Excessive tool wearExcessive tool wear Good work and process planning necessaryGood work and process planning necessary It can be difficult to find and recruit advanced It can be difficult to find and recruit advanced

staffstaff

CONCLUSIONSCONCLUSIONS HSM is not simply high cutting speed .It should be HSM is not simply high cutting speed .It should be

regarded as a process where the operations are regarded as a process where the operations are performed with very specific methods and precision performed with very specific methods and precision equipmentequipment

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

HSM is performed in finishing in hardened steel with HSM is performed in finishing in hardened steel with high speeds and high feeds often with 4-6 times high speeds and high feeds often with 4-6 times conventional cutting speedsconventional cutting speeds

HSM is high productive machining in small HSM is high productive machining in small sized components in roughing to finishing and sized components in roughing to finishing and in finishing to super finishing in components in finishing to super finishing in components of all sizes.of all sizes.

Even though HSM is known for a long time, Even though HSM is known for a long time, the research are still being developed for the research are still being developed for further improvement of quality and further improvement of quality and optimization of cost.optimization of cost.