Sandblasting service


Abrasive blasting, more commonly known as sandblasting, is the operation of forcibly propelling a stream of abrasive material against a surface under high pressure to smooth a rough surface, roughen a smooth surface, shape a surface or remove surface contaminants. A pressurised fluid, typically compressed air, or a centrifugal wheel is used to propel the blasting material (often called the media).



There are several variants of the process, using various media; some are highly abrasive, whereas others are milder. The most abrasive are shot blasting (with metal shot) and sandblasting (with sand). Moderately abrasive variants include glass bead blasting (with glass beads) and plastic media blasting (PMB) with ground-up plastic stock or walnut shells and corncobs. Some of these substances can cause anaphylactic shock to individuals allergic to the media. A mild version is sodablasting (with baking soda). In addition, there are alternatives that are barely abrasive or nonabrasive, such as ice blasting and dry-ice blasting.


Why should sandblasting be pre-treated?


The pretreatment stage of the sandblasting process refers to the treatment that should be carried out on the surface of the workpiece before the workpiece is sprayed and sprayed with a protective layer. The quality of the pre-treatment of the sandblasting process affects the adhesion, appearance, moisture resistance and corrosion resistance of the coating. If the pretreatment work is not done well, the rust will continue to spread under the coating, causing the coating to fall off in pieces. The surface that has been carefully cleaned and the workpiece that is generally cleaned simply can be compared with the coating by exposure method, and the lifespan can be 4-5 times different. There are many methods of surface cleaning, but the most commonly accepted methods are: solvent cleaning, pickling, hand tools, power tools.


What equipment is required for the sandblasting process?


Sandblasting machine is the most widely used product of abrasive jet. Sandblasting machine is generally divided into two categories: solid sandblasting machine and liquid sandblasting machine. Solid sandblasting machine can be divided into two types: suction type and pressure type.


1. Solid sand blasting machine


1-1, Suction type solid sand blasting machine is composed of six systems, namely structural system, medium power system, pipeline system, dust removal system, control system and auxiliary system.


The suction-type solid sand blasting machine is powered by compressed air, and the negative pressure formed in the spray gun through the high-speed movement of the air flow, the abrasive is sucked into the spray gun through the sand conveying pipe and ejected through the nozzle, and sprayed onto the surface to be processed to achieve the desired processing purpose. . In a suction dry blasting machine, compressed air is both the power supply and the acceleration power.


1-2, the press-in solid sand blasting machine consists of four systems, namely pressure tank, medium power system, pipeline system, and control system.


The press-in dry sand blasting machine is powered by compressed air, and through the working pressure established by the compressed air in the pressure tank, the abrasive is pressed into the sand conveying pipe through the sand outlet valve and injected through the nozzle, and sprayed onto the surface to be processed to achieve the desired processing purpose. In the press-in dry sandblasting machine, the compressed air is both the feeding power and the acceleration power.


2. Liquid sandblasting machine


Compared with the solid sandblasting machine, the biggest feature of the liquid sandblasting machine is that the dust pollution during the sandblasting process is well controlled and the working environment of the sandblasting operation is improved.


A complete liquid sandblasting machine generally consists of five systems, namely structural system, medium power system, pipeline system, control system and auxiliary system. The liquid sandblasting machine uses the grinding liquid pump as the feeding power of the grinding liquid, and the grinding liquid (mixture of abrasive and water) is evenly stirred into the spray gun through the grinding liquid pump. As the acceleration power of grinding fluid, compressed air enters the spray gun through the air pipe. In the spray gun, the compressed air accelerates the grinding fluid entering the spray gun, and is ejected through the nozzle and sprayed onto the surface to be processed to achieve the desired processing purpose. In the liquid sandblasting machine, the grinding liquid pump is the feeding power, and the compressed air is the acceleration power.


Sandblasting grade classification:


There are two representative international standards for the cleanliness of sandblasting: one is “SSPC-” formulated by the United States in 1985; the second is “Sa-” formulated by Sweden in 1976, which is divided into four grades: Sa1, Sa2, Sa2.5, Sa3 are international common standards. The details are as follows:


Sa1 level – equivalent to the US SSPC-SP7 level. The general simple manual brushing and abrasive cloth grinding methods are used, which is the lowest level of the four cleanliness levels, and the protection of the coating is only slightly better than that of the untreated workpiece. Technical standard for Sa1 level treatment: The surface of the workpiece should be free of oil, grease, residual oxide scale, rust, and residual paint. Sa1 level is also called manual brushing and cleaning level. (or cleaning grade)


Sa2 level – equivalent to the US SSPC-SP6 level. The sandblasting method is adopted, which is the lowest level in sandblasting, that is, the general requirement, but the protection of the coating is much higher than that of manual brushing. Technical standard for Sa2 level treatment: The surface of the workpiece should be free from greasy, dirt, scale, rust, paint, oxides, corrosion, and other foreign substances (except for defects), but the defects are limited to no more than the surface area per square meter. 33%, may include slight shadow; a small amount of slight discoloration caused by defects and rust; oxide scale and paint defects. If the original surface of the workpiece is dented, slight rust and paint will remain on the bottom of the dent. Sa2 grade is also called commodity cleaning grade (or industrial grade).


Sa2.5 level – is a level commonly used in industry and can be used as acceptance technical requirements and standards. Sa2.5 level is also called near-white clean-up level (near-white level or out-of-white level). Technical standards for Sa2.5 treatment: the same as the first half of Sa2, but the defects are limited to no more than 5% of the surface per square meter, which may include slight shadows; a small amount of slight discoloration caused by defects and rust; oxide scale and paint defects .


Sa3 level – equivalent to the US SSPC-SP5 level, is the highest treatment level in the industry, also known as white cleaning level (or white level). The technical standard of Sa3 level treatment: the same as Sa2.5 level, but 5% of shadows, defects, rust, etc. must not exist.


Application of sandblasting process:


(1) The coating of the workpiece and the sandblasting before the workpiece bonding can remove all dirt such as rust on the surface of the workpiece, and establish a very important basic schema (the so-called rough surface) on the surface of the workpiece, and can By exchanging abrasives with different particle sizes, for example, the abrasives of Feizhan abrasives can achieve different degrees of roughness, which greatly improves the bonding force between the workpiece and the paint and plating. Or make the bonding parts more firm and better in quality.


(2) Cleaning and polishing of rough surfaces of castings and workpieces after heat treatment Sandblasting can clean all contaminants (such as oxide scale, oil and other residues) on the surfaces of castings and forgings and workpieces after heat treatment, and polish the surface of workpieces to improve the smoothness of workpieces , can make the workpiece reveal a uniform and consistent metal color, so that the appearance of the workpiece is more beautiful and good-looking.


(3) Burr cleaning and surface beautification of machined parts Sandblasting can clean the tiny burrs on the surface of the workpiece, make the surface of the workpiece smoother, eliminate the harm of burrs, and improve the grade of the workpiece. And sandblasting can make small rounded corners at the junction of the workpiece surface, making the workpiece more beautiful and more precise.


(4) Improve the mechanical properties of the parts. After sandblasting, the mechanical parts can produce uniform and fine uneven surfaces on the surface of the parts, so that the lubricating oil can be stored, thereby improving the lubrication conditions, reducing noise and improving the service life of the machine.


(5) Lighting effect For some special-purpose workpieces, sandblasting can achieve different reflections or matts at will. Such as the grinding of stainless steel workpieces and plastics, the polishing of jade articles, the mattization of the surface of wooden furniture, the pattern of frosted glass surfaces, and the textured processing of cloth surfaces.

Examples of Sandblasting service

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