Metal surface treatment series knowledge——shot blasting/sand blasting

　　Surface treatment is to form a layer with one or more special properties on the surface of the material through physical or chemical methods. Surface treatment can improve product appearance, texture, function and other aspects of performance. The Development of Metal Surface Treatment With the rapid development of the metal processing industry, railway manufacturing industry, and automobile industry, there are higher requirements for the quality of various metal products and railway and automobile parts products. Long-term practice has proved that some simple , Simple pre-treatment methods can no longer meet the basic requirements of metal processing and painting. Only by adopting standard pre-treatment production processes can a standard layer of phosphate film and protective film be formed on the steel surface to meet the quality requirements of metal processing and coating treatments. Therefore, choosing low-cost, low-energy consumption, and high-quality metal pretreatment products is an important factor for companies to ensure the stability of coating quality and protection quality. The principle of shot blasting/sand blasting is to use a motor to drive the impeller body to rotate (directly driven or driven by a V-belt), and rely on centrifugal force to remove projectiles with a diameter of about 0.2 to 3.0 (including cast steel shots and steel wires). Cut shot, stainless steel shot and other different types) are thrown to the surface of the workpiece to make the surface of the workpiece reach a certain roughness, making the workpiece beautiful, or changing the welding tensile stress of the workpiece to compressive stress to increase the service life of the workpiece. By increasing the roughness of the workpiece surface, the paint film adhesion of subsequent painting on the workpiece is also improved. Sandblasting Sandblasting uses compressed air as power to form a high-speed jet beam to spray the spray material (copper ore, quartz sand, emery, iron sand, Hainan sand) onto the surface of the workpiece that needs to be processed at high speed.The appearance or shape of the outer surface of the workpiece surface changes. Due to the impact and cutting effect of the abrasive on the workpiece surface, the surface of the workpiece obtains a certain degree of cleanliness and different roughness, which improves the mechanical properties of the workpiece surface, thus improving the The fatigue resistance of the workpiece increases the adhesion between it and the coating, prolongs the durability of the coating film, and is also beneficial to the leveling and decoration of the coating.

　　Compared with other cleaning processes (such as pickling, tool cleaning), the sandblasting process has the following characteristics:

　　1.Sandblasting is the most thorough, most versatile, fastest and most efficient cleaning method.

　　2. Sandblasting can arbitrarily choose between different roughnesses, but other processes cannot achieve this. Manual polishing can produce a matte surface but the speed is too slow, while chemical solvent cleaning will make the surface too smooth, which is not conducive to coating adhesion.

　　Features of shot peening:

　　1. Great flexibility in cleaning. It is easy to clean the inner and outer surfaces of complex workpieces and the inner walls of pipe fittings; and it is not restricted by the site and can be moved to the vicinity of extra large workpieces for cleaning.

　　2. The equipment has a simple structure, low investment in the whole machine, few wearing parts, and low maintenance costs.

　　3. It consumes a lot of energy and must be equipped with a high-power air compressor station.

　　4. The cleaning surface is prone to moisture and embroidery.

　　5. The cleaning efficiency is low, there are many operators, and the labor intensity is high.

　　Characteristics of shot blasting:

　　1. Poor flexibility. Due to the limitations of the site, cleaning the workpiece is somewhat blind, and it is easy to create blind spots on the inner surface of the workpiece that cannot be cleaned.

　　2. There is no need for compressed air to accelerate projectiles, and there is no need to set up a high-power air compressor station.

　　3. The cleaned surface is not prone to moisture and embroidery.

　　4. The equipment structure is relatively complex and has many wearing parts, especially blades and other parts, which require long maintenance hours and high costs.

　　5. High cleaning efficiency, low cost, few operators, easy to realize automatic control, and suitable for mass production.