Electrochemical Machining

From Wikipedia, the free encyclopedia:

Electrochemical machining (ECM) is a method of removing metal by an electrochemical process. It is normally used for mass production and is used for working extremely hard materials or materials that are difficult to machine using conventional methods. Its use is limited to electrically conductive materials.
ECM is often characterized as “reverse electroplating“, in that it removes material instead of adding it. It is similar in concept to electrical discharge machining (EDM) in that a high current is passed between an electrode and the part, through an electrolytic material removal process having a negatively charged electrode (cathode), a conductive fluid (electrolyte), and a conductive workpiece (anode); however, in ECM there is no tool wear. Unlike EDM, no sparks are created. High metal removal rates are possible with ECM, with no thermal or mechanical stresses being transferred to the part, and mirror surface finishes can be achieved.
As far back as 1929, an experimental ECM process was developed, although it was 1959 before a commercial process was established.
The process remains a niche technique.
The ECM process is most widely used to produce complicated shapes such as turbine blades with good surface finish in difficult to machine materials. It is also widely and effectively used as a deburring process.

Advantages of our technology and the process in sharpening (pointing) Tungsten electrodes

  • Dimensional repeatability in series of parts is up to ± 0.5 micron (0.0005 mm) for tip radius.
  • No damage to sharp points possible, unlike with point grinding machines
  • Clean room safe packaging
  • 100% inspection on laser vision system for all critical dimensions
  • Ability to meet high volume demands
  • Competitive pricing due to highly automated process

Q & A about our Tungsten Needles, Pins, and Electrodes

Here we have answers to questions that we are asked frequently. Please send us an e-mail in case you have more questions. We will be glad to respond to you as soon as possible.


Q: What purity has your Tungsten wire?

A: All Tungsten wire we use in our process has a content of Tungsten => 99.5% unless otherwise specified.

Q: Why do you use ECM for pointing Tungsten electrodes, pins, and needles?

A: Using taper point grinding machines is good for stainless steel, but not for Tungsten wire. Due to the nature of the grinding process, the tip of a needle, electrode, pin, etc. is always in contact with the grinding wheel and can leave micro burrs. Also the transport of the finished needles in the point grinding machine can damage a sharp tip.

In contrast, ECM is done with the wire blanks in a special fixture where the blanks are spaced and not touching each other, or come in contact with any grinding media. The finished tip is always free of burrs. The tip geometry is much more consistent with ECM than when produced on a taper grinding machine.


Q: What is the shelf life of the Tungsten needles, pins, or electrodes?

A: For all practical purposes the shelf live is unlimited.


Q: Why do Tungsten needles or electrodes become black over time?

A: When Tungsten is exposed to air (oxygen) it will turn black on the surface.


Q: How can the black oxidation of Tungsten wire, needles, electrodes, etc. be cleaned?

A: A simple dip into water, best into an ultrasonic cleaner, will take the discoloration off in seconds. However, the wire has to be air dried immediately, for example with compressed air.


Q: Why is the surface finish of the tapered tip of a Tungsten needle, pin, or electrode matt and the shaft shiny?

A: The Tungsten wire material is shiny to begin with but the machining process of the tapered tip will leave a matt finish.


Q: Can I get Tungsten needles, pins, or electrodes with a shiny finish of the taper?

A: Yes, you can. This will be an additional step in the manufacturing process.


Q: Are there any disadvantages for a shine finish of the tapered tip?

A: The sharpness of the tip radius will be about 10% less than on tips with matt finish.


Q: What is the smallest tip radius you can produce?

A: The smallest tip radius depends on the wire diameter. For example, the tip radius on a wire of 0.75 mm (.030″) diameter can be as small as 1 my (0.001 mm). Smaller wire can result in an even smaller tip radius.


Q: How do you measure the tip radius?

A: We have several automatic Nikon vision systems that have a maximum magnification of 1,720 X. We measure the tip radius, length, as well as the tip profile. The collected data is saved in an Excel spreadsheet.


Q: Can you produce electrodes with sharp tips on each end? 

A: Yes, we have the capability to do so.