micro mach
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RECENT TRENDS OF“NON-CONVENTIONAL MICROMACHINING”
Taha Ali El-TaweelProduction Engineering and Mechanical Design
Faculty of Engineering, Shebin El-Kom, Menoufiya University
By
INTRODUCTION Electrochemical micro-machining (EMM)
Through-maskless - Through-mask Micro-electrodischarge machining (MEDM) Laser micro-machining (LMM)
Mask projection techniques - Direct writing techniques Micro-ultrasonic machining (MUSM) Chemical- micro machining (CMM)
Dry chemical etching - Wet chemical etching FUTURE POTENTIAL
LAYOUT OF THE PRESENTATION
Thermal Action- EDM- LBM- IBM
Mechanical Action- USM- WJM- AJM
INTRODUCTION
The need for fabricating parts from hardened high-strength and heat-resistant metals and alloys has created difficult machining problems for industry. To meet these problems, non-conventional machining methods have been developed. (no mechanical force)
Chemical ActionChemical Milling
Electrochemical Action- ECM
Non-conventional Machining
Micro-machining
The term micro-machining refers to material removal of small dimensions that range from several microns to one millimeter.
NON-CONVENTIONAL MICROMACHINING
• Electrochemical micro-machining (EMM)• Micro-electrodischarge machining (MEDM) • Laser micro-machining (LMM) • Ultrasonic micro-machining (USMM) • Chemical micro-machining (CMM)
The unit of removal can be of the order of atomic quantities through;
Electrochemical machining (ECM)Electrochemical machining (ECM) Ion exchange is the metal removal mechanism.- Reverse of electroplating- Workpiece must be electrically conductive- Electrolyte acts as a current carrier
- High rate of electrolyte movement; washes metal ions. - ECM for the production of gas turbine compressor blades
Principle of ECM machining
EMM through-maskless EMM through-mask
Electrochemical micro-machining
- Capillary drilling- MEJM
- One-sided EMM- Two-sided EMM
Electrochemical micro-machining (EMM)
Requires highly localized material removal induced by the impingement of a fine electrolytic jet.
Electrochemical micro-machining (EMM)
EMM through-maskless Micro electrochemical jet machining (MEJM)
Capillary drilling workpiece(anode)
nozzle diameter
electrolyte jet (cathode)
Insulation
glass tubeplatinum (cathode)
workpiece (anode)
electrolyte
MEJM Capillary drilling
Removes material by using an electrolyte jet from a small nozzle, which works as cathode without advancement of the jet.
Fine cathode tool in the form of a capillary that is advanced at constant rate towards the workpiece.
EMM through-mask
Involves selective metal dissolution from unprotected areas of a one- or two-sided photoresist-patterned workpiece.
The sample is held in a stationary holder while the multi-nozzle cathode, which is attached to the table, moves at a constant speed facing the sample
One-sided
Localized dissolution induced by scanning two cathode assemblies over a vertically held work-piece providing movement of the electrolyte
Two-sided
One-sided EMM Two-sided EMM
Electrochemical micro-machining (EMM)
Fabrication of micro-electronic components
Ink-jet nozzle plates Metal masks Micro-hole drilling Micro-surface production
Ink-jet nozzle
Photograph of micro holes Cylindrical micropin DC current
Pulse current
EMM applications
Micro gear pattern
Machining with ultra-short voltage
pulses
EMM applications
Micro grooves by wire ECM
Electrodischarge machining (EDM)
Electrical Discharge Machining (EDM) is a non-conventional machining technique in which the material is removed by the erosive action of electrical discharges (sparks) provided by a generator.
Benefits Widely accepted production technology -
2% of worldwide machining. High surface finishes Hardness of material not a concern Odd/Delicate shapes easier to produce Small holes easy to produce Heat treatment usually unnecessary
Drawbacks Slower machining time Surface integrity effects
Electrodischarge machining (EDM)
EDM Process Mechanism
Different Types of EDMDie-sinking EDM Wire EDM Machinable material » electrically conductive » semiconductor materials
Schematic illustration of EDM system Principle of WEDG
Can be made » micro shafts » micro holes » other complex shapes
Micro-electrodischarge machining (MEDM)
It is required for micro-machining to maintain the energy of a single discharge in the order of 10-6J to10-7J
E =1/2 (C + C') V 2
Reducing the discharge energy: » By reducing the discharge voltage » By reducing the total capacitance (C + C') Effective discharge control can be achieved,by Controlling parameters:» Discharge current» Open circuit voltage » Off-time» Polarity of electrode
Description of eroding pattern and overlapping pattern of discharge
MEDM applications
. MEDM of ceramics
Cross-sectional shape on the TiN coating and the EDMed surface
Micro-electrodes for and micro-pins
Fabrication of Micronozzle
Micro-hole drilling
positive polarity negative polarity
MEDM applications
Pagoda machined by micro wire EDM
Laser machining (LM)
– Heat treatment– Welding– Ablation– Deposition– Etching– Focused beam milling
Laser applications
Setup of the laser micro-machining
Highly focused optical energy of Laser is used to melt and evaporate workpiece portions in a controlled manner.- Refectivity and thermal conductivity of workpiece are important
- Widely used in automotive and electronics industries due to its accuracy, reproducibility, flexibility, ease of automation.
LMM applications
» Micro-machining of electrostatic electron lenses» Ink-jet printer nozzles» Micro-hole drilling » Micro-channels produced by mask projection» Manufacturing of 3D structures
Example geometries in WC/Co
Ink-jet printer nozzles
Micro-channelsMicro-holes
Ultrasonic machining (USM)Ultrasound - above 20 kHz, can be generated using peizoelectric or magnetostictive effects
- A formed tool, with the shape of the cavity to be machined is made to vibrate against the workpiece surface and between the two are placed abrasive particles (slurry).
- The material is removed in the form of grains by shear deformation, brittle fracture of work material; and by impact, cavitation and chemical reaction
Principle of USM
Micro-ultrasonic machining (MUSM)
Micro USM procedure
MUSM tools
The WEDG/EDM combination is used to generate co-axial micro-tool first, which MUSM of brittle materials carried out
Non-thermal, non-chemical and thus can produce a high-quality surface finish
The machining procedure of microtool
MUSM applications
» Micro-hole drilling
The entrance The exit
Micro air turbine.Center pin diameter 70 µm; rotor diameter 350 µm
Finishing
» Manufacturing of 3D s tructures
» Finishing EDMed parts
Chemical machining (CM))
# Chemical milling# Chemical blanking# Photochemical blankingUsed to make precise, microscopic holes microscopic grooves
Material removal from the surface by controlled chemical dissolution using reagents, etchants- acids/alkalies
» Dry chemical etching » Wet chemical etching
» Photoetching (lithography and isotropic etching)
Chemical-micro machining (CMM)
CMM applications
Surface etching Electrochemical etching
Chemical milling (surgical knife tool)
FUTURE POTENTIAL The use of ultra-short pulses
in EMM, MEDM & Laser to machine the widest choice of materials with very high quality.
Studying the effect of machining parameters on surface integrity of micro component.
Newest hybrid processes are suggested for micro-machining.
EMM with Laser Assistance (EMML)
EMM with MEDM MUSM with EMM & MEDM
Nanomachinery
Nanofabrication as another way to get into the nano domain
Nanomachinery
Aerospace: Gyroscopes, transducersBiomedical: DNA detection/separation devicesMolecular: sieves for protein sortingElectronics: Flexible (paper like) displays,nanowiresAutomotive: Accelerometers, pressure sensorsHealthcare: Nanotherapeutic devices, catheters,infusion pumps, intrauterine products
Industry Application Examples
Nanomachinery
Scanning probe microscopes have been used for the machining of nanofeatures ranging from ~100 nm down to atomic dimensions
Various approaches used are based on lithography, atomic and molecular level manipulation and material transfer, material modification by tip induced oxidation desorption hydrogenation or decomposition mechanical scratching of metals semiconductors and polymers.
Nano Machining Using SPM
Nanomachinery
Bottom-up processes Top-down processesContact printing, ImprintingTemplate growth Spinoidal wetting/dewettingLaser trapping/tweezerAssembly and joining (Self- and directed assembly)Electrostatic (coatings and fibres)Colloidal aggregation.
Lithography (E-beam, ion beam, Scanning probe, optical near field)
Energy beam machining (Laser, electron beam, ion beam)
Erosive processes (electrical, chemical, mechanical and ultrasonic)
Typical nanomachining processes
Nanomachinery
Nano groove (1000 × 150 × 2.4 nm )machinedin copper using atomic force microscope
Nanomachinery applications
5 μm deep spiral machined in Ni sheet Nanomachining by ECM
(a) Tungsten Tool(b) Structure in
Ni
Nanomachinery applications
Nanomachinery applications
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