Surface treatment technology: the difference between blasting and shot blasting

2019-12-02
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  Huicong surface treatment network: shot blasting is the use of high-speed rotating impeller to small steel or small iron shot throwing high speed impact on the surface of parts, so can remove the oxide layer on the surface of parts. At the same time, the steel or iron shot hits the surface of the part at high speed, causing the lattice distortion on the surface of the part and increasing the surface hardness. It is a method to clean the surface of the part. Shot blasting is often used to clean the surface of the casting or to strengthen the surface of the part.
  Generally, shot blasting is used for regular shape, etc., with high efficiency and little pollution.
  Repair, shipbuilding, shot blasting, sandblasting is widely used. But both shot blasting and sandblasting use compressed air. Of course, it is not shot blasting with high - speed rotating impeller. In repairing and shipbuilding industry, shot blasting (small steel shot) is mostly used in steel plate pretreatment (rust removal before coating); Sandblasting (repair, shipbuilding industry with ore) in the shape of the ship or section, the role is to remove the old paint and rust on the steel plate, repainting. In repair, shipbuilding, shot blasting, blasting the main role is to increase the adhesion of painting steel plate.
  In fact, casting part cleaning is not only with shot blasting, generally for large pieces of the first drum sand-cleaning, is the casting piece of the rising after the removal of the drum roll, by the parts in the drum collision, the surface of most of the sand to clear the first shot or shot blasting.
  The size of the shot balls is 1.5mm. Research shows that in terms of damage, and metal materials surface tensile stress is easier than compressive stress, when the surface is compressive stress, the fatigue life of material is greatly increased, therefore, for easy to fatigue fracture axial parts usually adopt shot peening forming surface compressive stress, increase product life, in addition, the metal is sensitive to tensile metal materials, this is the tensile strength of the material is larger than that of low compression strength of reason, it is also a general metal materials with the tensile strength (yield, tensile) show that the performance of materials.
  The steel plate working face of our daily car is reinforced by peening, which can significantly improve the anti-fatigue strength of the material. Blasting is a body with a motor to drive the impeller rotation, by the effect of centrifugal force, the diameter is 0.2 ~ 3.0 balls (have pills for casting, cut shots and stainless steel, etc.) to the surface of the workpiece, makes the artifact as beautiful, or change the workpiece welding tensile stress to compressive stress, improve the service life of the workpiece. Almost most areas for machinery, shipbuilding and ship repairing, auto parts, aircraft parts, guns tank surface, Bridges, steel structure, glass, steel, pipe, and so on. Sandblasting (pill) is using compressed air as power to sand diameter in 40 ~ 120 purpose or about 0.1 ~ 2.0 pill is sprayed to the surface of the workpiece, the workpiece to achieve The same effect. Pellet size is different, the treatment effect is not the same.
  Mainly put forward: peening can also play the role of strengthening. Now domestic equipment into a misunderstanding, that only blasting can achieve the purpose of strengthening. Each has its own advantages. For the workpiece like the gear, the shot blasting Angle cannot be changed, so the initial velocity can only be changed by frequency conversion.
  Sand blasting is a method of using compressed air to blow quartz sand out at high speed to clean the surface of parts. Also called blowing sand in the factory, not only to rust, but also to remove oil, very useful for painting. Often used for parts surface rust; Surface modification of parts (this is the purpose of small wet sandblasting machines sold in the market, where the sand is usually corundum and the medium is water); In the steel structure, the application of high-strength bolt connection is a more advanced method, because the high-strength connection is the use of friction between the joint surface to transfer the force, so the quality of the joint surface requirements are very high, this time must be treated with sandblasting on the joint surface.
  Sand blasting for complex shape, easy to use manual derusting, low efficiency, poor site environment, uneven derusting.
  General sandblasting machine has a variety of specifications of sandblasting gun, as long as it is not particularly small box, can put the gun into the clean.
  The head of the pressure vessel is sandblasted to remove the oxide skin from the workpiece surface. The diameter of quartz sand is 1.5mm ~ 3.5mm.
  There is a kind of processing is the use of water as a carrier, drive emery to process parts, is a kind of blasting.
  Shot blasting and sandblasting can clean and decontaminate the workpiece for the purpose of preparation for the next process, that is, to ensure the roughness of the next process requirements, but also for the consistency of the surface, shot peening on the workpiece has a strengthening effect, sandblasting is not obvious. Generally, peening is a small steel ball and blasting is quartz sand. According to different requirements, the number of items. Casting almost every day with sandblasting, shot blasting.
  Supplement:
  1. Shot blasting and sandblasting are surface treatments, but it doesn't mean only castings are shot blasting
  2. The main function is to surface derusting of sandblasting, in addition to scale, etc., such as the parts after heat treatment, and more: the role and function of blasting is not only cleaning, in addition to the surface scale, also improve the surface roughness, remove parts machining burrs, eliminate parts internal stress, reduce the deformation of parts after heat treatment, to improve the surface wear resistance parts, compression ability, etc
  3. There are many processes for shot peening, such as casting, forging, parts table after machining, parts table after heat treatment, etc
  4. Sandblasting is mainly manual operation, and shot blasting automation and semi-automatic more 5. The steel shot and iron shot used by shot blasting are not in fact balls in the sense, it is accurate to say that it is small steel wire or small steel rod, only after using for a period of time to look like the shot to hold? The so-called sandblasting sand, that is, river sand, and construction with no different, just sandblasting with the screen system, containing less mud, particle size specifications. Of course, some industries also have different, such as ship industry shot blasting with steel shot, sandblasting with metal ore (not river sand - quartz sand).
  Add (some repetitions, some conflicts) :
  1. Balls and sand balls are generally spherical particles without edges and corners, such as steel wire cut balls; Sand refers to angular sand grains, such as brown corundum, white corundum, river sand and so on.
  2. Spraying and jetting use compressed air as the driving force to spray sand or pellet onto the surface of the material to achieve cleaning and certain roughness. Blasting is the method of centrifugal force generated when the pellet is rotated at high speed, which impacts the surface of the material to achieve cleaning and certain roughness.

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