Your PECM Expertise Database

Know How and Frequently Asked Questions

Why ECM and PECM?

Electrochemical machining (ECM) is a method of removing metal by an electrochemical processy. It is employed in mass production for working extremely hard materials or materials that are difficult to machine using conventional methods.

Its use is limited to electrically conductive materials. ECM can cut small or odd-shaped angles, intricate contours or cavities in hard and exotic materials such as titanium, aluminides, inconel, Waspaloy and high nickel, cobalt and rhenium alloys.

Both external and internal geometries can be machined.

ECM is often characterized as reverse electroplating in that it removes material instead of adding it.

Pulsed electrochemical machining (PECM) is also non-contact, unconventional machining process based on the principles of electrolysis. The machining operation involves a tool (the cathode) in the inverse shape of the desired workpiece (the anode).

As the tool moves towards the workpiece surface, it machines the workpiece into the complementary shape of the tool. This occurs as a pulsed DC current is applied, allowing for high precision and superior surface quality.

At the same time, an electrolyte is pumped between the cathode and anode at high speed, removing dissolved metal and heat. 

The result is an operation capable of producing a burr-free 3D shape with no tool wear in alloys that are difficult or impossible to machine through traditional methods.

How exactly does PECM work?

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 PECM there is no tool wear.

The PECM cutting tool is guided along the desired path close to the workpiece but without touching the piece. Unlike EDM, however, no sparks are created. High metal removal rates are possible, with no thermal or mechanical stresses being transferred to the part, and mirror surface finishes can be achieved.

In the PECM process, a cathode (tool) is advanced into an anode (workpiece). The pressurized electrolyte is injected at a set temperature to the area being cut. The feed rate is the same as the rate of "liquefication" of the material. The gap between the tool and the workpiece varies within 80–800 micrometers (0.003–0.030 in.)

As electrons cross the gap, material from the workpiece is dissolved, as the tool forms the desired shape in the workpiece. The electrolytic fluid carries away the metal hydroxide formed in the process.

The ECM process is most widely used to produce complicated shapes such as turbine blades with very smooth surface finishes in difficult to machine materials.

Where does the technology originate from?

Electrochemical machining, as a technological method, originated from the process of electrolytic polishing offered as early as 1911 by the Russian chemist Shpitalsky.

As far back as 1929, an experimental ECM process was developed by Gussef, although it was 1959 before a commercial process was established by the Anocut Engineering Company. B.R. and J.I. Lazarenko are also credited with proposing the use of electrolysis for metal removal.

Much research was done in the 1960s and 1970s, particularly in the gas turbine industry. The rise of EDM in the same period slowed ECM research in the west, although work continued behind the Iron Curtain.

The original problems of poor dimensional accuracy and environmentally polluting waste have largely been overcome, although the process remains a niche technique.

In what applications is the technology used?

PECM technology is most widely used to produce complicated shapes such as turbine blades with good surface finish in difficult to machine materials.

What materials can be machined with PECM?

  • 4140

  • A2 Tool Steel

  • Al MMCs

  • Aluminum 6061

  • Aluminum 7075

  • AMZ4

  • Brass

  • Bronze

  • CMSX-4

  • Cobalt Chrome

  • Copper

  • Ferrium C64

  • GaSb

  • Germanium

  • Haynes 230

  • Inconel 625

  • Inconel 718

  • Inconel 738

  • Inconel 740h

  • InSb

  • M4 Tool Steel

  • MarM247

  • Molybdenum

  • MP35N

  • NdFeB

  • Nickel

  • Nitinol

  • Nitronic 60

  • Pyrowear 53

  • Rene N-5

  • Stainless 17-4

  • Stainless 304

  • Stainless 316

  • Stainless 440C

  • Ti Grade 2

  • Ti 64

  • TiAl

  • Vit105