electrochemical machining nov16th2010

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


Sportscar logo


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


Thin wall profile

Thickness=60, 45, 30 & 15 µm

Length=7mm

Height=1,5 mm


Heat exchanger cell

Process time: 6 min

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:


•Phase 3:

Small series production to optimize the process and to analyze

the parts.

• Phase 4:

Implementation of the application at the customers location.


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


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


Representatives

Customers

Thank you for your

attention

For more info please visit

www.electrochemicalmachining.com

electrochemical machining nov16th2010

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