Commonly used metal surface treatment methods and their characteristics

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Commonly used metal surface treatment methods and their characteristics

In the process of heat treatment, machining, transportation and storage, the metal surface will inevitably be oxidized, resulting in a layer of uneven thickness of oxidation. Let's summarize what are the common methods of metal surface treatment?
       Mechanical treatment method: mainly including shot blasting method and shot blasting method. Shot blasting method is a method of cleaning using centrifugal force to accelerate the projectile, and then blast it to the workpiece for rust removal. However, the flexibility of shot blasting is poor, limited by the site, some blindness when cleaning the workpiece, the inner surface of the workpiece is prone to clean up the dead angle. Equipment structure is complex, wearing parts, especially the blade and other parts wear fast, maintenance time, high costs, one-time investment.
       Chemical treatment: mainly is the use of acidic or alkaline solution and the surface of the workpiece oxides and oil chemical reaction, so that it dissolves in acidic or alkaline solution, in order to remove the surface of the workpiece rust oxidation and oil purpose. Chemical treatment is suitable for thin plate clean-up, but the disadvantage is: if the time is not properly controlled, even with corrosion inhibitors, can make the steel over-etching phenomenon.
       Manual processing: such as scrapers, wire brushes or grinding wheels. By hand can remove the surface rust and oxide skin, but manual processing is labor-intensive, low productivity, poor quality, and incomplete cleaning. For the hinge complex structural parts and parts with holes, after acid solution pickling, the residual acid immersed in the crevices or holes is difficult to remove completely, if not handled properly, will become a hidden danger of future corrosion of the workpiece, and the chemicals are easy to volatile, high cost, the chemical discharge after treatment is difficult, if not handled properly, will cause serious pollution to the environment.
       With the improvement of people's environmental protection, this treatment method is being replaced by mechanical treatment method. Shot peening is also divided into shot peening and sand blasting. The surface treatment with shot blasting, the strike force is large, the cleaning effect is obvious. However, the treatment of thin plate workpiece by shot blasting, easy to make the workpiece deformation, and steel shot to the workpiece surface deformation of the metal substrate, due to Fe3O4 and Fe2O3 no plasticity, broken and peeled, and oil film with the substrate deformation, so the workpiece with oil, shot blasting, shot blasting can not completely remove the oil.
       In the existing workpiece surface treatment methods, the best cleaning effect is also sandblasting cleaning. Sandblasting is applicable to the workpiece surface requirements of high cleaning. But our current general sandblasting equipment is mostly composed of hinged dragon, scraper, bucket elevator and other primitive and bulky sand transfer machinery.