Rotary Ultra Sonic Machining

8/10/2019 Rotary Ultra Sonic Machining

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R OTARY U LTRA S ONIC M ACHINING Presented ByAriz HusainAnkesh KapilSohan Lal SwamiAkshay Kumar

Pradeep Meena


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WORKING P RINCIPLE

Rotary ultrasonic machining (RUM) is a hybridmachining process that combines the materialremoval mechanisms of diamond grinding andUSM, resulting in higher material removal rate(MRR) than that obtained by either diamondgrinding or USM.In RUM, the slurry is replaced with abrasivesbonded to the tool. A rotating core drill with metal-bonded diamond abrasives is ultrasonically vibratedand fed toward to the work piece at a constantpressure or a constant feed rate.


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WORKING P RINCIPLE

Coolants pumped through the core of the drill washaway the swarf, prevent jamming of the drill, and keep itcool so that the RUM process could be conductedsmoothly.


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MECHANISM OF M ATERIAL R EMOVAL


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ROTARY ULTRASONIC MACHININGOF TITANIUM ALLOY: EFFECTS OF

MACHINING VARIABLESMachining Science and Technology: An

International Journal

N. J. Churi a , Z. J. Pei a & C. Treadwell


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ABSTRACT

This paper reports the experimental results on theeffects of spindle speed, feed rate, and ultrasonicpower on cutting force, material removal rate, andsurface roughness during rotary ultrasonicmachining of a titanium alloy.The experimental conditions and procedure aredescribed next. Then, experimental results arepresented and discussed, followed by the

conclusions.


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EXPERIMENTAL S ETUP AND C ONDITIONS

Machining experiments were performed on a machine ofSonic Mill Series 10.It mainly consists of an ultrasonic spindle system, a dataacquisition system, and a coolant system.

The ultrasonic spindle system comprises of anultrasonic spindle, a power supply, and a motor speedcontroller. The power supply converts 60 Hz electricalsupply to high frequency (20 kHz) AC output.

This is fed to the piezoelectric transducer located in theultrasonic spindle. The ultrasonic transducer convertselectrical input into mechanical vibrations.


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Experimental Setup


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MEASUREMENT P ROCEDURE

During rotary ultrasonic machining, the cutting forcealong the feed direction was measured by aKISTLER 9257 dynamometer.The dynamometer was mounted atop the machinetable and beneath the workpiece, as shown in theprevious Figure.The electrical signals from the dynamometer weretransformed into numerical signals by an A/Dconverter. Then the numerical signals to measurethe cutting force were displayed and saved on thecomputer with the help of LabVIEW


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MEASUREMENT P ROCEDURE

The material removal rate (MRR) in the rotaryultrasonic machining was calculated using thefollowing equation:

where, D out is the diameter of machined hole, D inthe diameter of machined rod, d workpiecethickness, and T the time it takes to drill the hole.


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Illustration of the hole and rod machined by rotary ultrasonicmachining


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RESULTS AND D ISCUSSIONS

Effects of Spindle SpeedOn Cutting ForceThe maximum cutting force vs. spindle speed curve isshown in Figure.The cutting force decreases significantly as the spindlespeed increases.It is also observed that the rate of decrease in thecutting force decreases when the spindle speedincreases.In summary, the spindle speed has significant effects oncutting force; the lower the spindle speed, thehigher thecutting force.


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Effects of spindle speed on cutting force.


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RESULTS AND D ISCUSSIONS

On Material Removal Rate (MRR)It can be seen that the spindle speed has no obviouseffects on MRR.


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On Surface Roughness Measured on the MachinedHole

The surface roughness becomes significantly lower asthe spindle speed increases.It is also observed that the rate of decrease of surfaceroughness decreases with the increase in spindlespeed. It can be concluded that spindle speed has

significant effects on surface roughness on themachined hole.

On Surface Roughness Measured on the MachinedRod

The surface roughness becomes significantly lower asthe spindle speed increases.It is also observed that the rate of decrease of surfaceroughness decreases with the increase in spindlespeed.


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EFFECTS OF F EED R ATE

On Cutting ForceThe cutting force increases significantly as the feed rateincreases, which is consistent with the observation byJiao et al. (33) and Li et al. (34) for rotary ultrasonic

machining of alumina and ceramic matrix composite,respectively.


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EFFECTS OF F EED R ATE On Material Removal Rate (MRR)

As shown in Figure, when the feed rate increases, MRRincreases.This is because that, as the feed rate increases, the tooltravels faster in downward direction causing an increase

in material removal rate.


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EFFECTS OF F EED R ATE

On Surface Roughness Measured on the MachinedRod

At lower feed rates, there is no significant increase insurface roughness. But at higher feed rates, the surface

roughness increases significantly.


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EFFECTS OF ULTRASONIC P OWER

On Cutting ForceCutting force decreases initially as ultrasonic powerlevel increases and then increases at the higher powerlevel.


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On Material Removal RateThe ultrasonic power has no significant effect on MRR.The MRR observed at various levels of ultrasonic poweris almost constant.


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The surface roughness measured on the machined holedecreases significantly as the ultrasonic power

increases.


It is observed that as the ultrasonic power increases,the surface roughness measured on the rod surfacedecreases significantly.


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Effects of ultrasonic power onsurface roughness measured onmachined hole.

Effects of ultrasonic power onsurface roughness measured onmachined rod.


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CONCLUSIONS The spindle speed has significant effects on cuttingforce and surface roughness, but its effects on materialremoval rate are not significant. Cutting force andsurface roughness decrease as the spindle speedincreases.

The feed rate has significant effects on cutting force,material removal rate, and surface roughness. Cuttingforce, material removal rate, surface roughnessincreases significantly as the feed rate increases.The ultrasonic power has significant effects on cuttingforce and surface roughness, but its effects on materialremoval rate are not significant. Cutting force decreasesinitially and then increases as the ultrasonic powerincreases. Surface roughness decreases as theultrasonic power increases.


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ADVANTAGES

Experimental results [Prabhakar 1992] have shown thatthe machining rate obtained from RUM is nearly 6-10times higher than that from a conventional grindingprocess under similar conditions.

It is much easier to drill deep and small holes with RUMthan with USM.Other advantages of improved hole accuracy and lowtool pressure are also reported [Graff 1975, Stinson1979].RUM is a non-thermal, non-chemical and non-electricalprocess. As a result the metallurgical, chemical orphysical properties of the workpiece do not change postmachining

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Rotary Ultra Sonic Machining