Difference between shot blasting and sand blasting

Shot blasting is to use the high-speed rotating impeller to throw out small steel shot or small iron shot and hit 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, steel shot or iron shot impacts the part surface at high speed, resulting in lattice distortion and deformation of the part surface and increasing the surface hardness. It is a method to clean the part surface. Shot blasting is often used to clean the casting surface or strengthen the part surface.

Generally, shot blasting is used for regular shapes. Several polishing heads are up, down, left and right together, with high efficiency and little pollution.

Shot blasting and sand blasting are widely used in the repair and shipbuilding industry. However, whether shot blasting or sand blasting, compressed air is used. Of course, it is not shot blasting that requires a high-speed rotating impeller. In the repair and shipbuilding industry, shot blasting (small steel shot) is generally used in steel plate pretreatment (rust removal before coating); Sand blasting (mineral sand used in repair and shipbuilding) is mostly used in formed ships or sections to remove the old paint and rust on the steel plate and repaint it. In the repair and shipbuilding industry, the main function of shot blasting and sand blasting is to increase the adhesion of steel plate coating paint.

In fact, the casting cleaning is not just shot blasting. For large parts, the drum sand cleaning is generally carried out first, that is, the riser of the casting is cut off and then rolled in the drum. The parts collide with each other in the drum, and most of the sand on the surface is cleaned first, and then shot blasting or shot blasting is carried out.

The size of shot blasting ball is 1.5mm.

The research shows that in terms of damage, when there is tensile stress on the surface of metal materials, it is much easier than compressive stress. When there is compressive stress on the surface, the fatigue life of materials is greatly improved. Therefore, for parts prone to fatigue fracture such as shafts, shot peening is usually used to form surface compressive stress to improve the service life of products. In addition, metal materials are very sensitive to tension, which is why the tensile strength of materials is much lower than the compressive strength, This is also the reason why metal materials generally use tensile strength (yield, tensile) to represent material properties.

The steel plate working surface of our daily car is strengthened by 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 balls with a diameter of 0.2 ~ 3.0 (including cast shot, cut shot, stainless steel shot, etc.) are thrown to the surface of the workpiece to make the surface of the workpiece reach a certain roughness, make the workpiece beautiful, or change the welding tensile stress of the workpiece to compressive stress, so as to improve the service life of the workpiece Almost used in most fields of machinery, such as ship repair, auto parts, aircraft parts, gun and tank surface, bridge, steel structure, glass, steel plate, pipeline, etc Sand blasting (shot) is to use compressed air as power to spray sand with a diameter of 40 ~ 120 mesh or shot with a diameter of about 0.1 ~ 2.0 onto the surface of the workpiece to achieve the same effect The treatment effect is different with the size of pellets It is emphasized that shot peening can also play a strengthening role Now the domestic equipment has entered a misunderstanding that only shot blasting can achieve the purpose of strengthening Enterprises in the United States and Japan use shot blasting for strengthening! Each has its own advantages For example, for the workpiece like gear, the shot angle of shot blasting cannot be changed, and the initial speed can only be changed by frequency conversion However, it has large processing capacity and fast speed, while shot blasting is just the opposite. The effect of shot blasting is not as good as that of shot blasting.

Sand blasting is a method that uses compressed air to blow out quartz sand at high speed to clean the surface of parts. It is also called sand blowing in the factory. It can not only remove rust, but also remove oil. It is very useful for coating. It is often used for rust removal on the surface of parts; Surface modification of parts (this is the purpose of small wet sand blasting machine sold in the market. The sand is usually corundum and the medium is water); In the steel structure, the application of high-strength bolts for connection is a relatively advanced method. Because the high-strength connection uses the friction between the joint surfaces to transfer the force, the quality requirements of the joint surface are very high. At this time, the joint surface must be treated by sand blasting.

Sand blasting is used for complex shape, easy to remove rust by hand, low efficiency, poor site environment and uneven rust removal.

General sandblasting machines have sandblasting guns of various specifications. As long as it is not a particularly small box, you can put the gun in and clean it.

The supporting product of pressure vessel – the head adopts sand blasting to remove the oxide skin on the workpiece surface, and the diameter of quartz sand is 1.5mm ~ 3.5mm

One kind of processing is to use water as a carrier to drive emery to process 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 process, that is, to ensure the roughness requirements of the next process. In order to ensure the consistency of the surface, shot blasting can strengthen the workpiece, so sand blasting is not obvious. Generally, shot blasting is small steel ball and sand blasting is quartz sand. Number of sub items according to different requirements.

Sand blasting and shot blasting are used in precision casting almost every day.