Ultrasonic Assisted Machining - Map Your Show

Ultrasonic Assisted MachiningIntroducing Intense Vibrations to EnhanceMetalworking

Presentation Overview—————Introduction to UltrasonicsHigh Power UltrasoundUltrasonic Assisted MachiningApplication ExamplesAcoustech Systems

Introduction to Ultrasonics— Intense, inaudible acoustic waves— Field of extreme breadth— Low‐intensity, high‐frequency applications— High‐intensity, low‐frequency applicationsEngineeringLife SciencesEarth SciencesLow BassNotes20 HzInfrasound20 kHzAcousticDiagnosticNDE2 MHzUltrasound200 MHz

Presentation Overview—————Introduction to UltrasonicsHigh Power UltrasoundUltrasonic Assisted MachiningApplication ExamplesAcoustech Systems

High Power Ultrasound— HPU is the application ofintense acoustic energy tocreate change in a material orprocess— Transducer is heart of system—Converts electrical energyto mechanical—Establishes resonanceClassic TransducerUS MachiningTransducerPower supplyUltrasonicTransducer60 Ultrasonic energycauses change inMaterial or ProcessTransmissionMaterial/Process

A Note on Vibrations Longitudinal mode is singlemost important mode ofvibrationStresslf xNodeAmplitude Expansion/contraction natureof longitudinal vibrations Natural frequency Nodes and antinodes Amplitude, stress distribution Wavelength - λAntinodeE Steel, Al : c 5.1 103 m / sat 20 103 Hz (20kHz)c5.1 103 2 f 2 20 103 0.128 m 12.8 cm 5 in. l λ/2c,c 2lcylinder-20khz.avi(1 MB)

Introduction of Cutting ToolsNode Antinodencfn 2 n 1, 2, 3,

Vibrations in Cutting Tools

Isolating Vibrations from Machine— Node of a resonant devicetheoretically has no displacement— There are no nodes in ultrasonics— Recall animation of simple bar— There has to be a means of holdingthe system and applying forceStatic, Case M ounted20.0018.0016.00Long. Node Amp Displacement14.00Radial Amp at Nodal PositionBore Face Amp Displacement12.00Tool Tip DisplacementBack Mass Long. Amp Displacement10.00Radial Amp at Back MassLong. Amp. @ Tool Holder Interface8.00Rad. Amp. @ Back End of Case6.00Rad. Amp. @ Node Position w ith 0%120.00%

Presentation Overview—————Introduction to UltrasonicsHigh Power UltrasoundUltrasonic Assisted MachiningApplication ExamplesAcoustech Systems Products

Ultrasonic Assisted MachiningWhat is Ultrasonic Machining?Ultrasonic Vibration Conventional Machining(Drilling, Reaming, Turning, Milling,.)Changing the Cutting Process Reducing Dynamic Friction Reduces cutting forces Reduces heat generated in cutNote: UM is not .Ultrasonic‐based Slurry Drilling Process

Fundamental Ultrasonic System— Ultrasonic Module— 20kHz nominal resonant frequency— 5‐25µm tool tip displacement— ER‐32 collet— Through spindle coolant— Acoustech Power supplyUltrasonic Assisted Machining Module— Operating bandwidth of 19,000‐21,000Hz— Controls operating frequency—Maintains desired tool tipdisplacement—2.5kW maximum output powerUltrasonic Generator

System Characterization— Amplitude— Critical process variable— Measured as tool tipdisplacement in peak‐to‐peakmicrometer values— Frequency— Critical velocity3070025600mV500Displacement ‐ micron— Matching processesToolTip Laser Vib Data800mV— Not a variable, determined bynatural resonance of drill— Changes with tool length andgeometry— Must be considered for everytooling 5060 %Amp708090100

A Note on Bandwidth————Some shifting of resonant frequency can beaccommodatedPresence of other modesAmplitude is most critical parameterLoading effectsHigher power required to maintainresonance200015001000Acceleration (g)—5000-500-1000-1500-200018.2kHz01234Time (sec)Strain Gauge toMeasure AmplitudeAmplitude Profile During Drillingof Off‐tuned System519.8kHz21.2kHz

Applying Ultrasonics to Drilling— Objective is to reduce force required to make cut—Friction phenomena of ultrasonics reduces forces andtranslates to less heat generation—Potential benefits with reduced heat—Better tool life, burr reduction, increased feed rates, better tolerances,improved surface finish, microstructure changes

Mechanism of UAD3 General MethodsThrust force and Torque in UAD Empirical Models Analytical Models Finite Element ModelsTime consuming and ExpensiveUse Regression analysis to fit the equationsMore precise model than the Empirical modelRequire study of cutting process in depthCheaper model and faster analysisUse to optimize the drill bit geometry and cutting conditions

Research ApproachesChang and Bone’s model for conventional drilling [1]Tool wedge model offered by Merchant (1941)The chips in this model are formed along shear planandMeasurable by dynamometerMerchant’s CircleMost of the fundamental works on metal cutting use the following relations derived from his work.FF cos λɣFF sin λɣ cos λ ɣsin φ cos φ λ ɣ sin λ ɣsin φ cos φ λ ɣ w h cos λ ɣsin φ cos φ λ ɣ w h sin λ ɣsin φ cos φ λ ɣ

AssumptionsTwo main assumptions in the current (Chang & Bone) model are:Cutting lips(1) Drill bit cutting edge forcesChisel Edge(10‐20%of total force)Twist Drill Cutting Sections(2) Orthogonal cutting rather than Oblique cuttingSecondary Cutting zoneIndentation zoneOrthogonal Vs. Oblique

Building Analytical ModelsEvaluating the current analytical modelsTotal ForceGeometry of the cutting edgeSumming the force components at each elementTotal Thrust forceCutting edge divided into a number of elementsΣ&Cutting force Feed forceFor each element

Analytical ModelsHow to calculateCutting Force FFeed Force FF cos λF sin λwhere shear strength of materialw width of cuth uncut chip thicknessɣɣ& cos λ ɣsin φ cos φ λ ɣ sin λ ɣsin φ cos φ λ ɣ w h cos λ ɣsin φ cos φ λ ɣ w h sin λ ɣsin φ cos φ λ ɣλ friction angleɣ rake angleφ shear angleThrust force for each element Total Thrust force ̅, sin cos, sin

Notes on ModelingUsing an Oblique Cutting Model rather than using the Orthogonal Cutting ModelOrthogonal cutting (2D cutting model)FTFCCutting edge is normal to the cutting velocityIn order to better understand this complex processSimplifiedOblique cutting (3D cutting model)The cutting edge is inclined by an angle I (or λ)More realistic chip flow representationComplicatedFTFCFR

Calculating Thrust ForcesInputChisel edgethickness (mm)Drill point litude (Micron)Web thickness(mm)2.249MFrequency (kHz)Chisel edgeDiameter (mm)12.7BetaSpeed (RPM)PFeed (mm/rev)W’Number ofelementsW(Degrees)D’Helix angleDDiameter(mm)Drill bit geometry and cutting conditions0‐200Test 1Test 2Test 3Test 4Test 51000Spindle speed (RPM)Feed rate (mm/rev)0.1140.1140.1140.1140.114A e thrust force (N)OutputThrust Force

FEA of ProcessFE modeling of ultrasonic assisted drilling process is in progress .

Presentation Overview—————Introduction to UltrasonicsHigh Power UltrasoundUltrasonic Assisted MachiningApplication ExamplesAcoustech Systems Products

Drilling of Titanium 6Al‐4V————Amplitude0%60%60%System setup after characterization and tuning of toolsTesting initiated to arrive at most significant force reductionIncrease feed rates to obtain near original forcesEvaluate surface finish, hole quality, burr formation, microstructureRPM995995995IPM13.513.517.5IPRForce (N) Torque (Nm)0.0136121829.380.0136 Data762.325.53Drilling0.0176884.537.74Ra (µm)1.44741.00631.3561Baseline testingLocation 1Baseline with U.S.Advanced with U.S.Location 22316.024860% ‐ 995RPM ‐ 13.5IPM16.014716.042616.037516.042616.034360% ‐ 995RPM ‐ g surface roughnessMeasuring hole diameter

Material Impact

Drilling of 4340 Steel and 6061 Aluminum4340 RForce (N) Torque (Nm).00698489.708Drilling Data.00694177.165.025586623.68Ra (µm)0.44150.16440.2397Baseline testingLocation 1xBaseline with U.S.Advanced with U.S.Location 2yxyTotal AverageBaseline12.5425212.5349 12.5374 12.539912.539100% ‐ 2161RPM ‐ 15IPM12.5374412.5349 12.5349 12.529812.534100% ‐ 2161RPM ‐ 55IPM12.5298212.5349 12.5399 12.529812.5346061‐T6 AlumRow .6311.631818IPR0.00750.00750.010.01IPT Avg. Force (N) # of 8.911Avg. Ra(µm)2.40742.62512.40642.6721Bore Size (mm)0.48470.48560.48250.4845Aluminum Test Sample

Micro‐Drilling Titanium Post— Application Details— Significant tool breakage at engagementdue to spherical geometry— Slow processing speeds— Ø 0.45mm solid carbide drill— Results— Increased throughput by increasing peckdepth, chip load, and RPM— Tool life increased due to betterengagement cutting on centerTrial Amplitude RPM IPM IPR10%3538 1.37 .00039230%4500 2.25 .0005Peck Depth (in).005.027DoC (in) Cycle Time.023:55.20:52Figure 1: Fixture and tooling setup.

Drilling Hard Materials— Powder Metallurgy – Rc 72

Milling and Drilling Tungsten— Objective to mill flat on cylinder andconduct drilling trials to evaluate toolingwear— Results— Milling used Guhring solid carbide end mill improvedsurface finish (Ra 2.12µm vs. 4.34µm)— 4538 RPM, 47.66 IPMInitial Tungsten Sample— Drilling used High‐Tech TSC carbide to drill 1.1” deep— 3600 RPM, 22.6 IPMPost Testing SampleEnd mill cutting edgepost milling two partsDrill edge post drilling12 test holes

Ultrasonic Assisted ReamingBaseline ResultsForce (N)169.0Torque (Nm)2.141Surface Finish (Ra µm)0.2648Bore Size (mm)8.014At baseline settings (1406RPM– 22.5IPM), an axial feed forceof 169N was achieved.Ultrasonic ResultsForce (N)108.0Torque (Nm)0.9525Surface Finish (Ra µm)0.6153Bore Size (mm)8.024At the same baseline settingsadding ultrasonic energy, thefeed force was dropped by36%.Ultrasonics Applied at 150% of baseline feed rateForce (N)123.9Torque (Nm)1.816Surface Finish (Ra µm)0.2839Bore Size (mm)8.031Utilizing ultrasonics, feed ratewas increased by 150%, from22.5IPM to 34.5IPM, and theaxial force was 27% less thanthe baseline force.

Ultrasonic Tapping— Evaluate force reductions on applied force and torque for solid carbide tap— Stainless steel and titanium “gummy materials”— Harder materials often rely on thread milling resulting in lower throughputUltrasonic AmplitudePowerSupplyRPMIPMIPRAxial Force (N)Torque 0.0591685.49530%L.D.80947.81190.0591625.975 0591455.48530%Std.80947.81190.0591386.272 9523.713Summary of Tapping Study performed on 4340 Alloy steel

US Milling Titanium Peripheral Plate Milling 1,700 RPM, 0.02” DoC, 0.5” engagement,7 IPM Flood coolant Guhring, Ø1/2” solid carbide, 5” OALScale reference: Plate thickness 0.75”, DOC 0.2” No UltrasonicsRa 198Climb millingTaper cut (DoC .018‐.012) Ultrasonics (7µm)Ra 50Climb millingNo taper (DoC .019)38% load reduction along feed axis

Titanium Milling cont. Peripheral T‐Plate Milling 1,700 RPM, 0.02” DoC, 0.5” engagement,7 IPM 0.25” thick rib, 5”tall, “T” section Guhring, Ø1/2” solid carbide, 5” OAL No UltrasonicsRa 130Climb millingTaper cut (DoC .017‐.011) Ultrasonics (7µm)Ra 40 (above cut)Climb millingNo taper (DoC 0.18)14% load reduction along feed axis

High Aspect Ratio MillingTop Surface EngagementSurface Finish Result

Understanding Tooling Affects— Understanding acoustics withconventional cutting tools— “Common” drill (3d, 5d, 8d) – symmetricaland same diameter— Insert or carbide tip – still symmetrical— Indexable tool with short flute length— Custom grind stepped carbide— Note gain in amplitude due to reductionat end of tool— Decrease in diameters does not directly impactfrequency, but massremoved from flutes does!— Custom form tooling— Note changes in flute design, diameters, andgeometry— All three tools will tune similarly because they areroughly the same lengthwhile having different amplitude profiles

Presentation Overview—————Introduction to UltrasonicsHigh Power UltrasoundUltrasonic Assisted MachiningApplication ExamplesAcoustech Systems Products

Historical BackgroundCincinnati Milacron USturning, 1960’sGrumman US Drilling,1970’sOSU, US Cutting 1970’sSonobond Drilling,Turning 1970’s