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Electrochemical
MachiningA non-conventional metal machining technology
Metaalbewerking middels alternatieve
technieken vereist alternatieve kijk op
materiaaleigenschappen
SIG Material Analysis Hans-Henk Wolters
November 16th 2010
ECM
� What is ECM?� Fundamentals of ECM/ theory� Process description� Process animation� Material characteristics� Advantages and disadvantages of ECM� Photo gallery� Introduction of ECM Technologies
What is ECM?
•Electrochemical machining is a metal machining technology
based on electrolysis where the product is processed without
contact and thermal influence. The metal work piece is partially
dissolved (Machined) through electricity (Electro) and
chemistry (Chemical) until it reaches the required complex 3D
end shape.
•Unlike previous ECM techniques, the current ECM technique
benefits from pulsating power supplies and vibrating axis. This
concept enables processing products with a minimum process-
gap varying by single micrometers. The shape accuracy of the
end product depends on the size of the gap.
Fundamentals of ECM
Fundamentals of ECM•ECM
Electro Chemical Machining
•AMAnodic Machining•ECP
Electro Chemical Processing
•ECP
Electro Chemical Polishing
•ECP•ECP
Electro Chemical Plating
•CEChemical Etching•PPPlasma Polishing
•ECD
Electrochemical Deburring•ECD
Electrochemical Drilling•ECG
Electro Chemical Grinding•ECM
Electro Chemical Milling
Process description
Proces animation
http://www.youtube.com/watch?v=Z_U_ZZty5Ns
For a computer animation copy the following link into
your browser
Material characteristics
•Conventional machining
•Hardness
•Toughness
•Sintered
•Electrochemical machining
•Electrical conductivity
•Chemical composition•Chemical composition
•Heat treatment
•Existence of metal carbides
•Structure/ homogeneous/ phases
Fundamentals of ECMElectrochemical machinability coefficient Kv , specific
charge Qspec en velocity of dissolution Vf for various
materials
Specific charge Qspec:
(C/g)
F = Faraday constant
( =96485 C/mol)
x = fraction of element i
n = valence of dissolution of element i
Mw = molecular weight
(g/mol)
Ti 6-4 element percentage Oplosvalentie Molgewicht (g/mol)
ρ
(g/cm3)Qspec
(C/g)Vf / j
(µm/s)/(A/cm2)
Kv
(mm3/C)
Ti 90 4 47.904.5 8274
(8047)
0.267 0.0267Al 6 3 26.98V 4 5 (2) 50.94
Material characteristics
•Electrical parameters
•Current (density)
•DC, pulsed, bipolar
•Pulse length
•Pause length
•P/P ratio
•Electrolyte parameters•Electrolyte parameters
•Temperature
•pH
•Conductivity
•Salt type (single/ mixtures)
•Passivating/ non-passivating
•Measurements
•Efficiency
•Surface quality
•Surface roughness
•SEM analysis
Anode reaction : Me → Men+ + ne-
Anode reaction : 6H2O → O2↑ + 4H3O+ + 4e-
Phase 1: high speed machining, v ≈ 2,5 mm/min at 150A/cm2 DC
Phase 2: accurate machining
Fundamentals of ECM
High current density,
high MRR
Optimal current density,
accurate machining
Machining strategy in
passivating elecrolyte
Phase 3: polishing range
Non passivating electrolyte
Fundamentals of ECM
Increasing concentration
Fundamentals of ECM
Decreasing temperature
Advantages of ECM
•The product is free of burrs after processing
•No-contact process
- The process does not cause thermal or physical strain on the
product
- Unlike other machining techniques, no upper-layer deformation
occurs
•3-Dimensional products can be processed in one single step •3-Dimensional products can be processed in one single step
•High quality level attainable (Ra < 0,05 µm) depending on
material
•High dimensional accuracy attainable
•Material stress which releases during the process will be
compensated where possible
•Stainless steel in the upper-layer will be affected through various
machining techniques, as a result of which local rust formation
can occur. This is not the case with ECM
•Due to the ECM application it is possible to generate more
design of freedom for the product
•ECM is a technique with high machining speed at relatively low
costs
Advantages of ECM
•The hardness, toughness and thermal resistance do not affect
the material removal rate (MRR). For the machining of the
product it is also irrelevant if it is processed before or after a
heat treatment (hardening) step.
•MRR is high, approx. 1,5 cm3/min by 1000A DC.
•MRR is almost independent on the type of material
- Hard and tough alloys are machined as “quick” as for instance - Hard and tough alloys are machined as “quick” as for instance
aluminum
•Low running and tooling costs
•Initial investment in process design and electrode construction
are high, however the recurring costs are low
•“No” electrode wear
Disadvantages of ECM
•ECM was previously known as a environmental unfriendly
process. Through developments in the treatment of
electrolytes, the process has become less harmful to the
environment. The sludge can be re-used depending on the
machined material.
•Each product and material requires new research
•Higher production numbers are essential, as a special electrode •Higher production numbers are essential, as a special electrode
must be developed for each product. The ultimate best depends
on complexity and material.
•High power consumption but in general lower than other non-
conventional machining techniques.
•Design of electrode is complex and initially expensive,
however “the electrode will not wear”.
•ECM requires relatively high skilled staff.
Watch case
Process time: 25 min
Turbine wheel
Process time: 12 min
Sportscar logo
Process time: 22 min
Polished part
Ra< 0,05 µm
Process time: < 1 min
Microstructure
Diameter pilar 60-70 µm
Centre centre distance 200 µm
Height pilar 250 µm
Process time: 12 min
Thin wall profile
Thickness=60, 45, 30 & 15 µm
Length=7mm
Height=1,5 mm
Process time: 45 min
Heat exchanger cell
Process time: 6 min
1 mm
Introduction of ECM Technologies
ECM Technologies offers research on the feasibility of
applying electrochemical machining on metal products.
Consultancy and research (fundamental and application
based) is being offered for realizing new or optimizing
existing ECM processes.
The results from the research are used to design and specify The results from the research are used to design and specify
an electrochemical machining process to be implemented at
customers location.
Founded March 2003
When a customer requires a research, small series production/
prototype production and a customized machine then it is
possible to define the following phases.
• Phase1:
Fundamental research on the specific material.
•Phase 2:
Application research
•Phase 3:
Introduction of ECM Technologies
•Phase 3:
Small series production to optimize the process and to analyze
the parts.
• Phase 4:
Implementation of the application at the customers location.
Introduction of ECM Technologies
ECM Technologies is a small company with high skilled
ECM specialists on board.
ECM Technologies equipment;
•PEM Tec machine for application research
•ECD equipment developed by University of Eindhoven
•FCC research cell for fundamental research•FCC research cell for fundamental research
•Plasma polishing research set up
•VMB deburring/ polishing equipment
•Micro ECM machine
Introduction of ECM Technologies
ECM Technologies is working for customers in different
industries:
•Automotive
•Aerospace
•Space
•Medical
•Steel industry•Steel industry
•Energy market e.g. fuel cells
•Offshore industry
•Consumer products
•Watch industry
•Hygiene market
•etc
Introduction of ECM Technologies
Representatives
Customers
Thank you for your
attention
For more info please visit
www.electrochemicalmachining.com
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