Fabrication of micro-features and micro-tools using electrochemical micromachining

FABRICATION OF MICRO-FEATURES AND MICRO-TOOLS
USING ELECTROCHEMICAL MICROMACHINING
Submitted by:
Sayan Mallick (16ME61R14)
Mechanical Engineering Department
IIT Kharagpur

 Abstract
 Introduction
 Experimental Setup
 Micro Hole Drilling
 Micro Channel Cutting
 Micro Tool Fabrication
 Discussion
 Conclusion
 References

 Advanced machining process for
electrically conductive materials.
 In this setup a sewing needle with 47 μm
tip diameter as a tool.
 The fabrication of micro-tools
is done on a different setup.
 Variations of wire diameter and the
material removal rate with time are
studied.

 When ECM is used for fabricating features or structures in the
range from 1 to 999 μm, it is called electrochemical
micromachining.
 Used in many biomedical and engineering applications, especially
micro electro-mechanical systems and semiconductor industries.
 Effective for large scale production.
 Theoretically tool wear is zero.

Experiment
Fabrication of
micro-holes and
micro-channels
using
electrochemical
Micromachining.
production
of straight
micro-tools
using
electrochemical
Micromachining.

 A pulsed DC power supply is
used.
 Feed can be given simultan-
eously to all the motors or one
or any two at a time.
Tool & workpiece arrangement

 High conductivity, low viscosity, and non-corrosiveness.
 Environment friendly, and has a low cost.
Electrolyte
Non-Passive
electrolyte
(oxidizing anions such as
NaCl)
Passive electrolyte
(oxidizing anions such as
NaNO3, NaClO3)

Machining Parameters
Pulsed voltage - 02–10 V
Electrolyte - NaNO3
Concentration - 15–40 g/L
Feed rate - 00–1 mm/min
Inter-electrode gap -1000–4000
μm
Ton - 2.5–1,000 μs
Toff - 50–1,200 μs.
Measurements of the sewing needle

a. Completely insulated tool.
b. Tool after removal of insulation
from the tip
Needle and workpiece
arrangement

 Micro holes are drilled using Nickel coated Steel wire
(needle no. 8) as tool.
 Copper sheet with a thickness of 700 μm as workpiece.
Mathematical
Modeling

Machining Conditions For Making The Drills

Fabrication of micro-features and micro-tools using electrochemical micromachining

Drilled Holes Using Insulated Tool
Machining Parameters
Ton = 1,000 μs, Toff = 400 μs
Feed rate = 0.125 mm/min
Electrolyte concentration = 28 g/L.
Inter-electrode gap = 250 μm
Machining time is same for both

 Voltage, Ton, Toff & Electrolyte concentration are kept
constant.
 Variable parameters are IEG & Feed rate.
Machining condition for
Channel cutting

Schematic diagram of machined
channel cutting

Chemical Reactions
At anode: Fe → Fe++ + 2e− (dissolution of anode)
At cathode: 2H2O + 2e− → H2↑ + 2(OH)− (electrolysis)
In solution: Fe++ + 2(OH)− → Fe(OH)2 (reaction product)

Machining Parameters :
 A 0.1-M solution of H2SO4 with water is used as the
electrolyte.
 Pulsed DC voltage having amplitude = 6 V.
 Ton = 1,000 μs and Toff = 400 μs.

The amount of volume removed is calculated as
where L (30 mm) is the length of the electrode dipped in the
electrolyte, r2 is the initial radius & r1 is the radius calculated at every
5 minutes interval.
Initial Wire Fabricated Wire

Variation of MRR
With Time
Variation of Diameter
With Time

Variation of Diameter & MRR With Time

 The fabrication of several kinds of microstructures is possible using
ECMM.
 By controlling feeds in the X and Y directions, many kinds of shapes
of different sizes can be realized.
 A mathematical model is also developed which gives a relationship
between the machining parameters and the resultant hole diameter.
 In the case of straight-sided tool fabrication, when the diameter
reaches the range of 80–100 μm, the wire completely dissolves into
the solution in a short time because of the high MRR.

 Micro-holes and channels can be machined with high accuracy
using an insulated tool.
 The smallest micro hole of 51 μm diameter and a micro-channel of
average 315 μm width have been obtained on the sheets.
 The designed setup can be used for making straight micro-tools,
which in turn can be used to machine the desired micro-features on
the workpiece without changing the tool position.

 This process will be very useful for mass production
industries.
 The tool is able to maintain its positional accuracy.
 By maintaining the minimum gap between the tool and
workpiece in the case of channel cutting, a uniform width
of micro-channel can be achieved.

 V. K. Jain & Subodh Kalia & Ajay Sidpara & V. N. Kulkarni (2012)
Fabrication of micro-features and micro-tools using
electrochemical micromachining. Int J Adv Manuf Technol (2012)
61:1175–1183DOI 10.1007/s00170-012-4088-1
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