Chemical Milling is a method of selectively etching metal surfaces with chemical reagents to obtain specific shapes or sizes of processing. It is widely used in aerospace, electronics, automotive fields, especially suitable for thin-walled parts or complex shapes processing. However, in the process of chemical milling, in addition to the need to remove the material processing surface, the other non-processing surfaces (i.e., non-processing surfaces) are also prone to erosion by the etching liquid. Therefore, effectively protecting non-processing surfaces is a key link in the chemical milling process.



The core of protecting non-processing surfaces lies in the use of appropriate surface protection technology. Typically, this process includes the following steps:



1. Surface Cleaning and Pretreatment

Before applying the protective layer, the surface of the workpiece must be thoroughly cleaned to remove oil, oxides, and impurities to ensure that the protective layer can be firmly attached. Common cleaning methods include solvent cleaning, alkaline washing, acid washing, and ultrasonic cleaning.



2. Coating Protective Layer

The protective layer is generally made of materials with good corrosion resistance, such as rubber coatings, plastic coatings, wax materials, or special anti-etch inks. These materials are coated on the non-processing surface to form an isolation layer, preventing the etching liquid from contacting the metal surface. Coating methods include brushing, spraying, dipping, and screen printing, and the choice should be determined according to the shape of the workpiece and the requirements of mass production.



3. Precise Removal of Protective Layer

For areas that require processing, the protective layer must be precisely removed using mechanical or laser methods to expose the metal surface to be etched. This process requires high precision to avoid damaging the protective layer of non-processing areas.



4. Etching Processing and Post-treatment

After the etching is completed, residual etching liquid should be promptly removed, and the protective layer should be stripped off to carry out neutralization cleaning to prevent residual chemicals from causing secondary corrosion or contamination of the metal surface.



In practical applications, advanced processes such as masking technology (Masking Technology) and selective spraying can also be used to further improve the accuracy and efficiency of protection. For example, in the aerospace field, the use of photoresist as an etching material combined with ultraviolet exposure technology can achieve the protection of micrometer-level fine processing areas.



In summary, the protection of non-processing surfaces during chemical etching is not only related to the processing accuracy and surface quality of the product, but also directly affects the yield and production cost. Therefore, scientifically selecting protective materials, optimizing coating processes, and improving stripping accuracy is of great significance for improving the overall process level of chemical etching. With the continuous development of new materials and technologies, the future of chemical etching will achieve greater breakthroughs in terms of precision, efficiency, and environmental protection.