Electrochemical Machining (Electrochemical Machining, abbreviated as ECM) is a non-contact precision machining technology that uses the anodic dissolution principle of metals in electrolytes for material removal. It is widely used in the shaping processing of complex shapes, high-hardness materials, and difficult-to-machine materials. In the electrochemical machining process, the control of the corrosion rate is one of the key factors ensuring processing accuracy, surface quality, and processing efficiency. This article will discuss the main factors affecting the corrosion rate in electrochemical machining and the control methods.



Firstly, the type and concentration of the electrolyte are one of the key factors affecting the corrosion rate. Different electrolytes have different dissolution capabilities for metals. For example, sodium chloride (NaCl) and sodium nitrate (NaNO₃) are commonly used in the electrochemical machining of steel materials. Increasing the concentration of the electrolyte can enhance its conductivity and reactivity, thereby accelerating the corrosion rate; however, an excessively high concentration may also cause the temperature of the processing area to rise, even triggering side reactions, affecting processing quality.



Secondly, current density directly affects the dissolution rate of the anode metal. Within a certain range, increasing current density can significantly improve the corrosion rate, but an excessively high current density may cause local overheating or bubble accumulation, leading to non-uniform corrosion and reducing processing accuracy. Therefore, the rational selection of current density is crucial for achieving stable and controllable corrosion rates.



In addition, the control of the processing gap also has an important impact on the corrosion rate. A smaller processing gap can improve the uniformity of the current density distribution, accelerate the corrosion rate, and enhance processing accuracy; however, an excessively small gap may cause poor fluidity of the electrolyte, resulting in low concentration of electrolyte locally, which may reduce efficiency. Therefore, in actual processing, the gap parameters should be optimized according to material properties and processing requirements.



Temperature is also an important variable affecting the corrosion rate. During the electrochemical machining process, current passing through the electrolyte generates heat, leading to an increase in system temperature and consequently accelerating the reaction rate. However, an excessively high temperature can intensify side reactions, produce a large amount of gas, and affect processing stability. Therefore, it is usually necessary to maintain the stability of the electrolyte temperature through a cooling system.



In summary, the control of corrosion rate in electrochemical machining is a complex process with multi-factor coupling. By accurately adjusting key parameters such as the composition and concentration of the electrolyte, current density, processing gap, and temperature, corrosion rate can be effectively controlled while ensuring processing quality. In the future, with the development of intelligent control technology and new electrolytes, electrochemical machining will move towards higher efficiency and more precise control.