Nonconventional machining

Nonconventional machining

Nonconventional machining

Machine Tools and ProcessesBy Rushikesh Urunkar JJMCOE

Abrasive jet machining (AJM)Electrical discharge machining(EDM) Electro-chemical machining (ECM)Laser beam machining (LBM)Ultrasonic machining (USM)Water jet machining(WJM)

By Rushikesh Urunkar JJMCOE

Abrasive jet machining (AJM)


Abrasive materials Aluminum oxide Silicon carbide Dolomite (calcium magnesium carbonate)Sodium bicarbonate Glass beads Size of abrasive Around 25mMedium Air or co2Velocity -150 to 300m/secPressure 2 to 8kg/cmNozzle WC with orifice .05-0.2mmNozzle tip distance 0.25-15mm


Work material Hard and brittle materials like glass, ceramics, mica etcMachining operations Drilling, cutting, debarring, cleaning




Advantages of AJMAbility to cut intricate hole shapes in hard and brittle materials Ability to cut fragile and heat sensitive materials without damage because there is no heating of working surface Low capital cost Machining of semiconductors

Limitations of AJMSlow material removal rate Low accuracy (0.1mm) due to stray cutting (taper effect) Embedding of the abrasive in the w/p surface may occur while m/cing softer materialsAbrasive powder can not be refuse unwanted waste material, especially material that is regularly thrown away from a house, factory, etc.:By Rushikesh Urunkar JJMCOE

Taper is also a problem Abrasive powder can not be reusedMachining accuracy is relatively poorerIt is not suitable for machining ductile materials There is always a danger of abrasive particles getting embedded in the work material, hence cleaning needs to be necessarily done after the operation By Rushikesh Urunkar JJMCOE

Applications :Cutting slots, thin sections, contouring, drilling, deburring and for producing intricate shapes in hard and brittle materials It is often used for cleaning and polishing of plastics , nylon and teflon components Frosting of the interior surface of the glass tubes Etching of markings on glass cylinders etc Machining of semiconductors By Rushikesh Urunkar JJMCOE

Electrical discharge machining (EDM)



Small Spark gap is about 0.01-0.50mm and spark frequency 200-500 KHzThe electric current is varied within a wide range from .5 to 400amp at 40-300V dc The dielectric fluid is pumped through the tool or w/p at a pressure of 2kg/cm Material removal rate(max) 5000mm/min Specific power consumption 2-10W/mm/min


Tool material Brass, copper, graphite, copper tungsten, tungsten carbide Dielectric fluid Hydrocarbon oils, kerosene liquid paraffin, silicon oils, aqueous solution of ethylene glycol

Materials that can be machinedAll conducting metals and alloys


Advantages The process can be applied to all electrically conducting metals and alloys irrespective of their melting points, hardness, toughness or brittleness Time of machining is less than conventional machining No mechanical stress is present in the process Fragile and slender w/ps can be machined without distortion Hard and corrosion resistant surfaces, essentially needed for die making, can be developed


Limitations Machining times are too long Excessive tool wear High specific power consumptionMachining heats the w/p considerably and hence causes change in surface and metallurgical properties Profile m/cing of complex contours is not possible at required tolerances


Applications The EDM provides economic advantage for making stamping tools, wire drawing and extrusion dies, header dies, forging dies, intricate mould cavities etc It has been extremely used for m/cing of exotic materials used in aerospace industry, refractory metal, hard carbide and hardenable steels Typical EDM applications includefine cutting with thread shaped electrode (wire cutting EDM)Drilling of micro-holes Thread cuttingHelical profile millingCurved hole drilling


Electro-chemical machining (ECM)



ECM is the controlled removal of metal by anodic dissolution in an electrolytic medium in which the w/p is the anode and a shaped tool or electrode is the cathode Tool material Cupper, brass or steel Power supply Constant voltage DC supply Voltage 5-30V dc Current 50-40000 Amp


Electrolyte Sodium chloride (common salt) Sodium nitrate Material removal rate 1600mm/min Specific power consumption7 W/mm/min (around 150 times more in comparison to conventional methods )


Advantages of ECM The machined work surface is free of stresses Burr- free surface Reduced tool wear No cutting forces are involved in the process No thermal damage Used for machining difficult to machine materials and complex shaped parts Any good electrically conducting material can be machined High surface finish of order of 0.1 to 2.0 microns Very thin sections, such as sheet metals can be easily m/ned without any damage or distortion


Disadvantages of ECM Non-conducting materials can not be machined high specific power consumption High initial and working cost Large floor space is required Designing and fabrication of tools is relatively more difficult Extremely fine corner radii, say less than 0.2mm, can not be produce Specially designed fixtures are required to hold the w/p in position, because it may be displaced due to the pressure of the inflowing electrolyteCorrosion and rusting of w/p, m/c tool, fixture etc by electrolyte is a constant menance


Applications Machining of hard to machine and heat resistant materials Machining of blind holes and pockets, such as in forging dies Machining of complicated profiles, such as of jet engine blades, turbine blades, turbine wheels etc Drilling small deep holes, such as in nozzle Machining of cavities and holes of irregular shapes Deburring of parts By Rushikesh Urunkar JJMCOE


Laser Beam Machining (LBM)LBM is a machining process in which the work material is melted and vaporized by means of an intense, monochromatic beam of light called the laser The heat produced in the small area where the laser beam strikes can melt almost any of the known material Light Amplification by Stimulated Emission of RadiationBy Rushikesh Urunkar JJMCOE

Energy level (Ruby LASER)


Energy level (Ruby LASER)By Rushikesh Urunkar JJMCOE


Principle :By Rushikesh Urunkar JJMCOE

Material removal technique Heating, melting and vaporization Tool material Laser beams in wavelength range of 0.4-0.6 mPower density As high as 107 W/mmOutput energy of laser and its pulse duration 20J, 1milli second Peak power 20 KWSpecific power consumption 1000 W/mm/min


Material removal rate 5mm/min Material of work piece All materials except those with high thermal conductivity and high reflectivity


Materials :Almost all materials can be cut/drilled with laser (steel and steel alloys(including those coated with lead, tin, zinc, nickel, paint or plastic), titanium, tantalum, nickel)Non metals which can be cut are pvc, reinforced plastic, leather, wood, rubber, wool and cotton, Inorganic materials like glass, ceramics, asbestos, mica, stone, alumina and graphite can also be cut or drilledDynamic balancing of precision rotating components, such as of watches


Applications Machining very small holes and cutting complex profiles in thin, hard material like ceramics and tungsten. Application includes sheet metal trimming, blanking and resistor trimming Drilling micro holes (up to 250m)Cutting or engraving patterns on thin films The laser beam is effectively used in welding and heat treatment of material


Engraving patterns on thin films


There is direct contact b/w tool (laser) and w/pMachining of any material including non-metals is possible, irrespective of their hardness and brittlenessWelding, drilling and cutting of areas not readily accessible are possible There is no tool wear problem Soft materials like rubber and plastics can m/cned Extremely small holes can be m/cned i.e drilling micro holes (up to 250 m)Cutting very narrow slots can be effectively used for welding of dissimilar metal as well Advantages :By Rushikesh Urunkar JJMCOE

High capital investment needed Highly skilled operator are needed Very large power consumptionLow material removal rate The process is limited to thin sheet plates(depth limitation) and where a very small amount of metal removal is involved Can not be effectively used to m/c highly heat conductive and reflective materials The machined holes are not round and straight Certain materials like fiber-glass reinforced materials, phenolics, vinyls etc. cannot be worked by laser as these materials burn, char and bubbleDisadvantages :By Rushikesh Urunkar JJMCOE

Life of the flash lamp is short Effectively safety procedures are required By Rushikesh Urunkar JJMCOE

Ultrasonic Machining (USM)


USM, Impact grinding or Ultrasonic grinding

Tapered shankBy Rushikesh Urunkar JJMCOE

Material removal mechanism : complex mechanism involving both fracture and plastic deformation by impact of grains due to vibrating tool

Tool material :Soft steel (generally used), monel metal or stainless steel Monel is a group of nickel alloys, primarily composed of nickel (up to 67%) and copper, with small amounts of iron, manganese, carbon, and silicon. Stronger than pure nickel, Monel alloys are resistant to corrosion by many agents, including rapidly flowing seawater.By Rushikesh Urunkar JJMCOE

Abrasive : Silicon carbide, Aluminium oxide, boron carbide or diamond dust (size:200 to 2000 grit 1000 for finishing) This process is suitable only for hard and brittle materials like carbide, glass, ceramics, silicon, precious stones, germanium, titanium, tungsten, tool steel, die steel, etc Medium : Slurry of water with 30-60% by volume of the abrasives Power : 0.2-2.5KWVibrating frequency and amplitude : 15 to 30 kHz as vibrating frequency 0.01 to 0.06 mm as amplitude of vibration


Cutting rate :Grain size of abrasiveAbrasive materialConcentration of slurryAmplitude of vibration FrequencyDecreases with ratio W/P hard. to tool hard.

Cooling System : A refrigerating cooling system is used to cool the abrasive slurry to a temp 5-6c


Extremely hard and brittle materials can be easily machinedIn machining operations likes drilling, grinding, profiling and milling operations on all materials both conducting and non conducting The operation is noiseless The machined workpieces are free of stressesVery high degree of surface finish is obtainedMetal removal cast is lowOperation of the equipment is quite safe

AdvantagesBy Rushikesh Urunkar JJMCOE

Low metal removal rate High rate of tool wearHole depth to diameter ratio of 10:1The cost of tool is also high Power consumption is quite high Difficulties are encountered in machining softer materials In order to maintain an efficient cutting action, the slurry may have to be replaced periodically The size of the cavity that can be machined is limitedThis process does not suit to heavy metal removal

Limitations : By Rushikesh Urunkar JJMCOE

Applications :This process is suitable only for hard and brittle materials like carbide, glass, ceramics, silicon, precious stones, germanium, titanium, tungsten, tool steel, die steel, etc Holes as small as 0.1 mm can be drilled as well as large holes can be made.It is mainly used for drilling, grinding, profiling, coining and threading operations on all materials both conducting and non conductingTool and die making , especially wire drawing dies, extrusion dies and forging dies


Available in portable 20 W to heavy machines 2000 WStomatology : Enabling a dentist to drill a hole of any shape on teeth without creating any painCoining operations for materials such as glass, ceramics etc Threading by appropriate rotating and translating the workpiece or tool. By Rushikesh Urunkar JJMCOE

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Water jet machining (WJM)

High-pressure waterOrifice Abrasive Focusing tube Cover By Rushikesh Urunkar JJMCOE

Material removal mechanism : High velocity jet made to impinge on workpiece. Jet pierces the work material and performs desired action.Water under pressure from Hydraulic accumulator is passed through orifice of nozzle to increase its velocity.In another type of machine abrasive particles added in high stream of water jet. (Hydrodynamic Abrasive Jet Machine)Orifice of nozzle : Dia. is usually varies from 0.08 to 0.5Exit Velocity : 920 m/s

Materials : Relatively softer and non metallic materials like paper boards, wood, plastics, asbestos, rubber, fibreglass, leather.All type of ferrous and non ferrous metals and alloys. By Rushikesh Urunkar JJMCOE

Abrasives : Silica, Aluminium oxide and garnet Grit Sizes : 60, 80, 100 and 120Focusing Tube WC 0.8 to 2.4 mm Pressure 2500 to 4000 bar Abrasive garnet and olivine - #125 to #60 Abrasive flow - 0.1 to 1.0 Kg/min Stand off distance 1 to 2 mm Machine Impact Angle 60o to 900 Traverse Speed 100 mm/min to 5 m/min Depth of Cut 1 mm to 250 mm Parameters : By Rushikesh Urunkar JJMCOE

Almost no heat generated on your partThere is no tool changingFast setup and programmingBetter edge finishNo mechanical stressesboth metal and non-metallic materialsAre very safeEnvironmentally friendly

Advantages :By Rushikesh Urunkar JJMCOE

Limitations :Water jet technology cuts slower than laser or other cutting processReducing material processing productivityHigher entry cost than the other cutting machinesAbrasive material used for cutting harder materials tends to be quite expensive.By Rushikesh Urunkar JJMCOE

Paint removal Cleaning Cutting soft materials Cutting frozen meat Textile, Leather industry ArtistsSurgery AerospaceCutting Pocket Milling Drilling Turning Nuclear Plant Dismantling

Application :


Engineering

Nonconventional machining