The difference between shot blasting and sand blasting
Shot blasting is the use of a high-speed rotating impeller to throw small steel shots or small iron shots out of the surface of the part at high speed, so the oxide layer on the surface of the part can be removed. At the same time, the steel shot or the iron shot hits the surface of the part at high speed, causing the lattice distortion of the surface of the part to be deformed and increasing the surface hardness. It is a method for cleaning the surface of the part. The shot blasting is often used to clean the surface of the casting or to strengthen the surface of the part. deal with.
Generally, shot blasting is used for regular shapes, etc. Several heads are placed up and down together, with high efficiency and low pollution. Shipbuilding, shot blasting and sand blasting are commonly used. But whether it is shot blasting or sand blasting, it is in the form of compressed air. Of course, it is not the impeller that does not use high-speed rotation. In the repair and shipbuilding industry, shot blasting (small steel shot) is mostly used in steel plate pretreatment (pre-painting before rusting); sand blasting (repairing and shipbuilding is using ore) is often used in forming ships or segments. The role is to remove the old paint and rust on the steel plate and repaint. In the repair and shipbuilding industry, the main role of shot blasting and sand blasting is to increase the adhesion of steel coating paint.
In fact, the cleaning of casting parts is not only the use of shot blasting. For large parts, the roller cleaning is first carried out. The risers of the castings are cut off and placed in the drum. The parts collide with each other in the drum, and the sand of the surface is mostly Clear it and then blast or blast. The size of the shot blasting pellet is 1.5mm.
Studies have shown that in terms of damage, the tensile stress on the surface of the metal material is much easier than the compressive stress. When the surface is under compressive stress, the fatigue life of the material is greatly improved. Therefore, it is usually sprayed on components such as shafts that are susceptible to fatigue fracture. The pellet forms surface compressive stress and improves product life. In addition, the metal metal material is very sensitive to stretching, which is why the tensile strength of the material is much lower than the compressive strength. This is also the tensile strength of the metal material (yield, anti-wear). Pull) indicates the reason for the material properties.
The working surface of the steel plate of the car we ride every day is reinforced with shot peening, which can significantly improve the fatigue strength of the material.
Shot blasting is to use the motor to drive the impeller body to rotate. By the action of centrifugal force, the ball with diameter of 0.2~3.0 (with casting pill, cutting pill, stainless steel pill, etc.) is thrown to the surface of the workpiece, so that the surface of the workpiece reaches a certain rough. Degree, make the workpiece beautiful, or change the welding tensile stress of the workpiece to compressive stress, improve the service life of the workpiece. It is used in most fields of machinery, repair ship\auto parts\aircraft parts\gun tank surface\bridge \Steel structure\glass\steel\pipeline\etc. Sandblasting (pill) is to use compressed air as the power to spray the diameter of 40~120 mesh or 0.1~2.0 to the surface of the workpiece, so that the workpiece can reach the same Effect. The size of the pellets is different, and the treatment effect is different. The key point is that the shot peening can also play a strengthening role. Now the domestic equipment has entered a misunderstanding, and it is believed that only shot blasting can achieve the purpose of strengthening. \Japanese companies used to strengthen the blasting and use! Each has its own advantages. For example, a workpiece such as a gear, the shot angle of the shot blast can not be changed, only the frequency can be used to change the initial speed. But the amount it handles Big, fast, and shot peening is just the right The effect of blasting on a good shot no effect. Sand blasting is a method of using compressed air to blow out quartz sand at high speed to clean the surface of the part. The factory is also called sand blowing, not only to rust, but also to remove oil, which is very useful for painting. Commonly used for surface derusting of parts; surface modification of parts (small wet sand blasting machine sold in the market is this use, sand is usually corundum, medium is water); in steel structure, the application of high-strength bolts is a relatively advanced The method is because the high-strength joint uses the friction between the joint surfaces to transmit the force, so the quality of the joint surface is very high, and the joint surface must be treated by sand blasting.
Sandblasting is used for complex shapes, easy to remove by hand, low efficiency, poor on-site environment, and uneven rust removal. The general sand blasting machine has various types of sand blasting guns. As long as it is not a particularly small box, the gun can be put in and cleaned. The supporting product of the pressure vessel—the head is sandblasted to remove the scale on the surface of the workpiece. The diameter of the quartz sand is 1.5mm~3.5mm.
One kind of processing is to use water as a carrier to drive the emery to machine parts, which is a kind of sand blasting.
Both shot blasting and sand blasting can clean and decontaminate the workpiece. The purpose is to prepare for the next step, that is, to ensure the roughness requirements of the next process, and also for the consistency of the surface, the shot peening has on the workpiece. For reinforcement, sand blasting is not obvious. Generally, shot peening is a small steel ball, and sand blasting is quartz sand. According to different requirements, the number of points.
Precision casting is used almost every day with sand blasting and shot blasting.
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