Electrochemical Machining ECM

Electrochemical Machining fits in the category of machining as a manufacturing process. It involves

removal of material from a workpiece using electrolysis. This is achieved by connecting the

workpiece and the electrode to an electrical power supply. Similar to electrical discharge

machining the material for this process to work has to be electrically conductive, but unlike electrical

discharge machining the workpiece and electrode are immersed in an electrolyte fluid as opposed to

a dielectric fluid.

Electrochemical Machining Advantages

The main advantage of electrochemical machining is that it can be used to machine extremely hard

materials with no stressing. This is due to the absence of physical contact and heat. You will notice

that there are many similarities between electrochemical machining ECM and electrical discharge

machining EDM and consequently the advantages for both are also very similar, but ECM does have

some distinct advantages over EDM.

Advantages over EDM

thin section and fragile parts can be machined (no stress involved)

its faster than EDM

There is no tool wear with ECM, 

There is no heat involved

Tool can be made from soft electrode materials such as copper which is very easy to machine

Electrochemical Machining Disadvantages

The main disadvantage of electrochemical machining is that the process is not particularly

environmentally friendly. Not only is it a high energy process but it also produces a chemical sludge

that needs to be disposed of. In addition to that the equipment used has a tendency to become

corroded so requires frequent maintenance.

In terms of cost, equipment is also more expensive than standard machinery and equipment.

Electrochemical Machining Process

The process involves removing any electrically conductive material using anodic dissolution of the

workpiece in a stream of electrolyte. The electrolyte separates the workpiece which is the positive

anode side (+ve) from the tool electrode which is the negative cathode (-ve) side. The feed rate of

the tool is then matched to the dissolution rate of the workpiece with removal rate being governed by

Faraday's law which in practice means it is limited by the current and the electrolyte used. Features

machined into the workpiece are a mirror image of the tool and the quality of the machined finish is

inversely proportional to the rate of material removal.

Because there is no tool wear whatsoever, the tool can be made to any required shape out of a soft

material such as copper.

It is common practice to load several electrodes into one tool holder in order to machine complex

components with multiple cavities. The process can be duplicated very easily due to the fact there is

no tool wear. It is a simple case of changing out the workpiece and running the program again.

However compared to standard machining the cycle times would be considered quite long, but this is

somewhat offset by the faster setting up times involved and the lack of tool wear.