Shot blasting is to use the high-speed rotating impeller to throw small steel shot or small iron shot out of the high-speed impact part surface, so it can remove the oxide layer on the part surface. At the same time, steel shot or iron shot strikes the part surface at high speed, causing lattice distortion on the part surface and increasing surface hardness. It is a method of cleaning 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 shape, with several heads up and down, left and right, high efficiency and little pollution.
Shot blasting and sand blasting are widely used in repair and shipbuilding. However, both shot blasting and sand blasting use compressed air. Of course, it is not necessary to use high-speed rotating impeller for shot blasting. In the repair and shipbuilding industry, shot blasting (small steel shot) is generally used for steel plate pretreatment (rust removal before painting); Sand blasting (mineral sand is used in repair and shipbuilding industries) is mostly used in formed ships or sections to remove old paint and rust on steel plates and repaint them. In the repair and shipbuilding industry, the main role of shot blasting and sand blasting is to increase the adhesion of steel plate coating paint.
In fact, the cleaning of castings is not only by shot blasting. For large pieces, the drum sand cleaning is generally carried out first, that is, the riser of castings is cut off and rolled in the drum. Parts collide with each other in the drum, and most of the sand on the surface is removed before shot blasting or shot blasting.
The size of shot blasting ball is 1.5mm.
Research shows that, in terms of damage, it is much easier to damage metal materials when there is tensile stress on the surface than compressive stress. When there is compressive stress on the surface, the fatigue life of materials is greatly improved. Therefore, shot peening is usually used to form surface compressive stress for parts that are prone to fatigue fracture, such as shafts, to improve product life. 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, tension) to express material properties.
The working surface of the steel plate 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. With the effect of centrifugal force, shot with a diameter of 0.2~3.0 (including cast shot, cut shot, stainless steel shot, etc.) is thrown to the surface of the workpiece, so that the surface of the workpiece can reach a certain roughness, making the workpiece beautiful, or changing the welding tensile stress of the workpiece to compressive stress, so as to improve the service life of the workpiece It is almost used in most fields of machinery, such as ship building, automobile parts, aircraft parts, guns, tanks, surfaces, bridges, steel structures, glass, steel plates, pipes, etc. Sand blasting (shot blasting) 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 to the surface of the workpiece, so that the workpiece can achieve the same effect. Shot sizes are different, The treatment effect achieved is different. It is emphasized that shot peening can also play a role in strengthening. Now domestic equipment has entered a misunderstanding that only shot peening can achieve the purpose of strengthening. Enterprises in the United States and Japan use shot peening for strengthening! Each has its own advantages. For example, for a workpiece such as a gear, the shot blasting angle cannot be changed, and the initial speed can only be changed by frequency conversion However, it has a large amount of treatment and a fast speed, while shot peening is just the opposite. The effect of shot blasting is not as good as shot peening
Sand blasting is a method of using compressed air to blow quartz sand out 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, which is very useful for painting. It is commonly used for derusting the surface of parts; Surface modification of parts (small wet sand blasting machines sold in the market are used for this purpose. The sand is usually corundum and the medium is water); In the steel structure, it is an advanced method to use high-strength bolts for connection. Because high-strength connection uses the friction between the joint surfaces to transmit force, the quality of the joint surface is required to be high. At this time, the joint surface must be treated with sand blasting.
Sand blasting is used for complex shape, easy to remove rust manually, with low efficiency, poor site environment and uneven rust removal.
General sandblasting machines have sandblasting guns of various specifications, which can be put in and cleaned as long as the box is not too small.
The head, an auxiliary product of pressure vessel, is sandblasted to remove the oxide skin on the surface of the workpiece. The diameter of quartz sand is 1.5mm-3.5mm
One kind of processing is to use water as a carrier to drive the emery to process parts, which is sandblasting.
Both shot blasting and sand blasting can clean and decontaminate the workpiece, so as to prepare for the following sequence, that is, to ensure the roughness requirements of the next process, or to ensure the consistency of the surface, shot blasting can strengthen the workpiece, so the sand blasting is not obvious. Generally, shot blasting is small steel ball and sand blasting is quartz sand. Number of items according to different requirements.
Sand blasting and shot blasting are used almost every day in precision casting.
