Etching machine processing as a chemical cutting technology, its history can be traced back to a long time. In Europe, chemical etching machines became popular in the 15th century, mainly for the processing of armor and the etching of art. The earliest European text records that all etchant formulations are formulated with salt, activated carbon and vinegar. The earliest anti-corrosion material was recorded with a linseed oil coating as a protective layer. Later, some records also used paraffin wax as an anti-corrosion agent.

　　The 17th century is an era of medicinal chemistry and testing of the effects of acids and bases on various materials. John Graeberg has made a lot of progress in this area, including improvements to the hydrochloric acid manufacturing process. The application of chemical corrosion technology in the aviation industry in the future has also emerged. At that time, people used acid and iron filings to prepare hydrogen balloons for lifting. That is to say, in the initial stage of people's attempts to fly, the use of acid corrosion ability has been used to help the development of aviation. By the mid-1960s, due to the development of etching machine processing and anti-corrosion technology, etching machine processing has become a very practical production and processing method, which has been widely accepted in the aerospace industry.

　　Compared with other technologies, etching machining technology can make many parts simpler, easier and cheaper to produce, and it provides a method for machining some parts that is difficult to implement by machining methods. At the same time, etching machine processing, as a sophisticated and scientific chemical processing technology, is used in a variety of metal materials to etch a variety of different graphics and shape processing. In recent decades, with the development of the economy and the needs of the national defense industry, the application of etching machining technology has been paid more and more attention. For example, the development of tourist souvenirs, the manufacture of nameplates, medals, code plates and display electrodes, printing rolls and stencils, fine parts, etc., are inseparable from the etching process technology.

三. titanium alloy chemical etching machine processing liquid formula:

　　The titanium alloy etching machine mainly contains etching liquid, oxidizing agent and additives: (1) etching liquid

　　HF is a strong etchant over any other acid in the titanium alloy etching machine. In the HF solution at room temperature, titanium can be corroded, and as the acid concentration increases, the corrosion rate increases significantly.

　　(2)Oxidant

　　H2CrO4 and HNO3 are commonly used oxidants in etching machine fluids. Early titanium etching process, the etching solution widely used in the United States is a mixed acid etching machine based on HF and H2CrO4, and then the British adopt HF and HNO3. The basic mixed acid etching machine processing fluid. However, H2CrO4 has high cost, serious pollution to the environment, and the sample is easily hydrogen embrittled after reaction; while HNO3 acts as a strong oxidant and has strong oxidizing property, so that hydrogen is oxidized into water, inhibiting hydrogen absorption reaction and adsorbing titanium surface. Hydrogen is reduced.

　　(3)additive

　　The additive has the function of improving the surface quality of the sample. When the titanium alloy etching machine is processed, it is necessary to prevent defects such as air grooves, gullies, corrugations, ridges, pitting, etc. on the surface of the sample, and at the same time, reduce the hydrogen absorption and prevent the material. Hydrogen embrittlement occurs, and excellent surfactants have various effects such as reducing surface tension and wetting. It is difficult for an additive to have these effects at the same time. Therefore, it is necessary to simultaneously add several additives to synergistically on the premise of not affecting the mechanical properties of the material. Under the etching machine processing accuracy requirements. Titanium alloy etching machine processing should choose the following aspects when adding additive types:

　　① Whether the hydrogen absorption on the surface of the sample can be reduced during the reaction to prevent hydrogen embrittlement; ② No effect on the mechanical properties of the samples before and after processing; ③ The sample has a uniform dissolution rate and improves the surface quality of the sample.;

　　④ Does not affect the effectiveness of the various components of the etching machine processing fluid, so that the etching machine processing fluid life is extended

  四、Advantages and Limitations of Etching Machines: Etching machines have many advantages, and they are unique to some parts that are difficult to machine by mechanical methods:

1 It can process metal materials with high hardness and high toughness;

　　a. The etching machine can only perform cutting in a progressive manner based on the original surface state of the part. Therefore, the shape and surface quality of the parts after the etching process are directly related to the original shape and surface quality of the parts. More often, the machined surface after etching is completely parallel to the original initial reference surface state. It can be seen from these limitations that the etching machine cannot process parts with complicated shapes by using rough-surfaced plates, rods, and the like;

　　b. The etching process cannot be used to machine narrow and deep grooves because the bubbles generated during the etching process will accumulate under the edge of the corrosion protection layer. The bubbles trapped under the corrosion protection layer will make the metal surface The etchant is separated, causing a very irregular corrosion, forming very irregular edges, which is very disadvantageous for deep part processing;

　　c. Drilling can not be performed by etching machine. The etching machine is different from the mechanical method and the electrolytic method. It cannot process the hole shape that can be processed by the latter two. The right process can be used to drill a hole with a straight hole in the hole wall, while the etching machine can only drill an irregular hole. For deep etching machined drill holes, the etching time is increased due to the long corrosion time, so the etching machine drilling holes are generally not used;

　　d. During the processing of the etching machine, various acid liquids volatilize, which is easy to cause environmental pollution and affect personal health. 

五、Titanium alloy precision etching machine processing:

　　The dimensional accuracy of the etching machine is affected by two aspects: a. The deviation of the etching process itself during the machining process, which is caused by different corrosion speeds on the surface to be machined, which makes the thickness of the metal removed by the corrosion. Or the depth of corrosion is different. b. The accuracy of the corroded material. This refers to the deviation of the raw material itself before the chemical corrosion of the part, also known as the blank deviation. The tolerance in the etching process is the sum of these two precision deviations, so both deviations must be taken into account when performing the etching process, otherwise the parts machined by the etching machine will have a large degree of dimensional deviation. The machining tolerances of the etching machine are mainly affected by the following factors:

 1 The influence of the material composition of the parts:

　　六、Effect of etching machine on mechanical properties of materials:

　　After the metal is processed by the etching machine, the original mechanical properties will be affected to some extent, and this effect will increase as the degree of corrosion increases.