By: Alexander Ayala, Date: 02/11/2018
What is Electromechanical machining?
- Electrochemical Machining (ECM) is the process of applying a direct current to a tool (cathode), which accompanied by a usually saline electrolytic solution, removes the surface metal debris from the workpiece (anode) through electrolysis. The speed of the removal process is controlled by the DC current applied. As the tool is forced closer to the anode, the predetermined gap between the two is maintained. This results in the shape of the workpiece being complementary to that of the tool. Because of this, it is possible to machine relatively complex surface geometries with extreme precision.
- In 1911, the early stages of ECM was shown through a process called electrolytic polishing. It wouldn’t be until 1928 when two Russian engineers, V.N. Gusev and L. Rozhkov, improved the process by flushing electrolytic fluid through the interelectrode space and the electrode feeding with velocity equal to that of the anode debris.
- Electrochemical machining as a technological method was offered by Russian chemist E. Shpitalsky in 1911 and was improved by V.N. Gusev and L. Rozhkov in 1928.
- In 1959, the Anocut Engineering Company in the USA began production of the traditional model of ECM.
- The following industries all benefit from the use of ECM: aerospace, automotive, biomedical, etc. Applications of ECM to the corresponding fields can produce pistons, turbine blades, surgical blades, etc.
- Benefits to using ECM include lowering the time required to cut the material because ECM does not depend on the hardness or toughness of the material. Also, the workpiece is not subjected to any mechanical or thermal stresses. Accompanied with no tool wear, this means the first finalized product will be the exact same as the next 85,000 copies. Another plus is the ability to machine parts at a nano level and have a clean surface finish, completely burr free.
- Tolerances of +/- 2-5 μm can be expected.
- Some shortcomings to using ECM are that it does not work on non-conducting materials and the initial tooling can be timely and costly.
- Before the ECM process can be started the tool needs to be machined so the resulting workpiece is its complementary form. Once the tool is created, the DC power source directly connected to the cathode is turned on. The machine forces the tool closer to the workpiece which causes the surface layer of the workpiece to continuously shed off the metal debris. While this occurs, the electrolytic solution is constantly being pumped between the gap of the tool and workpiece to remove the metal debris.
- The electric current combined with the electrolytic solution allows for the electrolysis process to take place at the cathode. This process frees the hydroxide ions (OH-) which combine with the metal ions of the anode. This forms insoluble metal hydroxides that are removed from the anode by the electrolytic fluid.
- An ECM machine requires only an operator. The operator must have the necessary programming experience and understanding of the final product to ensure accurate results.
- Specific equipment costs, tooling and unit costs vary by company and require a quote from the manufacturer, however, it is known to be quite expensive.