Non-Traditional Machining

(NTM) processes

Samples Objects

Types

• Chemical: Chemical reaction between liquid

reagent and workpiece: etching

• Electrochemical: Electrolytic reaction at

workpiece surface

• Mechanical: High velocity liquid or abrasives

remove material

• Thermal: Evaporation due to localized high

temperature

Summary of NTM processesFeed, mm/m(ipm)

Roughness, AA

um(uin)

Accuracy mm(in) Feature size cm(in)

Contd..Feed, mm/m(ipm)

Accuracy mm(in) Feature size cm(in)Roughness, AA

um(uin)

NTM Finishing Processes

Roughness and Tolerance variation

Chemical Machining (CHM): Steps

Inconel 718 engine parts: Chemical milling to

remove weight

Formed work piece liquid rubber coated

template scribed finished part

Missile skin panel weight reduction

Typical CHM Defects

Photochemical machining

Etch Methods and undercutting

Etch Factor, E=U/d

Anisotropy, A = d/U = 1/E

Wm = Wf – 2*E*d

Different Etchants

min

Electrochemical Machining (ECM)

tIKn n-number of moles removed

I-current

t-time of current applied

ECM Relation

Parts

Typical parts made by electrochemical machining. (a) Turbine blade made of a nickel alloy, 360 HB; note the shape of the electrode on the right. Source: ASM International. (b) Thin slots on a 4340-steel roller-bearing cage. (c) Integral airfoils on a compressor disk.

Types of ECM

Mechanical NTM processes

Ultrasonic Machining

Waterjet Cutting

Waterjet machining

Hydrodynamic

machiningPressure: 60000 psi

Jet dia: 0.003-0.20in

Velocity: 3000ft/sec

Nozzle: Synthetic sapphire (wear

resistant)

Impinging pressure > compressive

stress

Soft non-metals, plastics, etc.

Water-Jet Machining

(a) Schematic illustration of water-jet machining. (b) A computer-controlled, water-jet cutting machine cutting a granite plate. (c) Examples of various nonmetallic parts produced by the water-jet cutting process. Source: Courtesy of Possis Corporation.

(c)

(a) (b)

Abrasive Waterjet cutting

Metals, plastics, rubber, glass, ceramics,

composites, etc.

Abrasive Flow

MachiningEdge finishing, deburring,

polishing, mirror surface

finishing..

Abrasives: Al.oxide, SiC,

BC, diamond.

Thermal NTM Processes

Electrical Discharge Machining

(EDM)

1000s of sparks/second.

Spark Erosion

Complex shapes

EDM principles

Erosion size depends on Current

and Time

Stepped EDM

•Coordinate x-y-z movement

•Special attachments

Wire EDM

E-Beam Machining

Laser Beam Machining

Types of Lasers

Micro/nano

fabrication