General knowledge of sandblasting rust removal
Sandblasting to remove rust is to use compressed air as the power to form a high-speed jet beam to spray material (copper ore, quartz sand, diamond sand, iron sand, Hainan sand) at high speed to the surface of the workpiece to be treated, so that the appearance or shape of the outer surface of the workpiece surface changes, due to the impact and cutting effect of the abrasive on the surface of the workpiece, so that the surface of the workpiece obtains a certain degree of cleanliness and different roughness, so that the surface of the workpiece Mechanical properties are improved, so it improves the fatigue resistance of the workpiece, increases the adhesion between it and the coating, prolongs the durability of the coating film, and also facilitates the leveling and decoration of the coating.
Application range of sandblasting
1, workpiece coating, workpiece bonding pretreatment sandblasting can remove all the dirt from the surface of the workpiece, such as rust skin, and establish a very important foundation pattern on the surface of the workpiece (i.e., usually called the hairy surface), and can achieve different degrees of roughness by swapping abrasives of different grain sizes, such as the abrasives of Feizhan abrasives, greatly improving the bonding force between the workpiece and the coating and plating material. Or make the bonding parts bonding more firmly and better quality.
2, casting parts burr surface, heat treatment after the workpiece cleaning and polishing sandblasting can clean the casting and forging parts, heat treatment after the workpiece surface of all the dirt (such as oxidation, oil and other residues), and the workpiece surface polishing to improve the finish of the workpiece, can make the workpiece to reveal a uniform and consistent metal original color, so that the workpiece appearance more beautiful, good-looking.
3、Machined parts burr cleaning and surface beautification sandblasting can clean up the workpiece surface of the tiny burr, and make the workpiece surface more flat, eliminating the harm of burr, improve the grade of the workpiece. And sandblasting can play a very small rounded corners at the junction of the workpiece surface, so that the workpiece appears more beautiful and more precise.
4, improve the mechanical properties of the parts mechanical parts by sandblasting, can produce uniform fine bumpy surface on the surface of the parts, so that the lubricant is stored, so that the lubrication conditions improve, and reduce noise to improve the service life of machinery.
5, the role of light finishing for some special-purpose workpiece, sandblasting can achieve different reflective or matte at will. Such as stainless steel workpiece, plastic polishing, jade polishing, wooden furniture surface matte, frosted glass surface pattern pattern, and fabric surface furring processing, etc.
1, before work must wear protective equipment, not allowed to work with bare arms. Work with no less than two people.
2, gas storage tank, pressure gauge, safety valve to be regularly calibrated. Gas storage tank once a fortnight to discharge dust, sand tank in the filter once a month to check.
3, check whether the ventilation pipe and sand blasting machine door is sealed. Five minutes before work, shall open the ventilation and dust removal equipment, ventilation and dust removal equipment failure, prohibit sand blasting machine work.
4, compressed air valve to slowly open, air pressure is not allowed to exceed 0.8MPa.
5, sandblasting particle size should be adapted to the work requirements, generally between ten and twenty applicable, sand should be kept dry.
6, sandblasting machine work, prohibit the approach of extraneous personnel. When cleaning and adjusting the operating parts, should be stopped.
7, is not allowed to use compressed air to blow dust on the body or joke.
8, after work, ventilation and dust removal equipment should continue to run for five minutes before closing, in order to discharge indoor dust, to keep the site clean.
9、In the event of personal and equipment accidents, the site should be maintained and reported to the relevant departments.
【Sandblasting process flow】
Sandblasting process pretreatment stage: sandblasting process pretreatment stage refers to the surface of the workpiece before being sprayed, plating protective layer, the workpiece should be processed.
Sandblasting process pre-treatment quality is good or bad, affecting the adhesion of the coating, appearance, moisture and corrosion resistance of the coating. If the pre-treatment work is not done well, the rust will still continue to spread under the coating and make the coating come off in pieces. After careful cleaning of the surface and general simple cleaning of the workpiece, using the exposure method for coating comparison, the life expectancy can be 4-5 times different. There are many methods of surface cleaning, but the most commonly accepted methods are: solvent cleaning, acid cleaning, hand tools, and power tools.
【Sandblasting process stage】
Sandblasting process is the use of compressed air as the power to form a high-speed jet beam, the spray material and other high-speed jet to the surface of the workpiece to be treated, so that the external surface of the workpiece appearance changes, due to the impact of abrasive on the surface of the workpiece and cutting effect, so that the surface of the workpiece to obtain a certain degree of cleanliness and different roughness, so that the mechanical properties of the workpiece surface is improved.
That is, cleanliness, representative of two international standards: one is the United States in 85 years to develop “SSPC-“; the second is Sweden in 76 years to develop “Sa-“, which is divided into four levels were Sa1, Sa2, Sa2.5, Sa3, for International customary common standards, detailed as follows.
Sa1 level – equivalent to the U.S. SSPC-SP7 level. The technical standard of Sa1 level treatment: The surface of the workpiece should be free from visible dirt such as oil, grease, residual oxidation, rust spots, and residual paint, etc. Sa1 level is also called manual brush cleanup level. (or sweeping grade)
Sa2 grade – equivalent to U.S. SSPC-SP6 grade. The technical standards for Sa2 level treatment: the surface of the workpiece should be free from visible grease, dirt, oxide, rust, paint, oxides, corrosion, and other foreign substances (except blemishes), but the blemishes are limited to no more than 33% of the surface per square meter and can Including slight shading; a small amount of minor discoloration caused by blemishes, rust; oxide and paint blemishes. If the original surface of the workpiece has dents, minor rust and paint will also remain at the bottom of the dents. sa2 grade is also called commodity cleanup grade (or industrial grade).
Sa2.5 grade – is commonly used in industry and can be used as a technical requirement and standard for acceptance. sa2.5 grade is also called near-white cleaning grade (near-white grade or out-white grade). Sa2.5 level treatment technical standards: the same as Sa2 requirements of the first half, but defects limited to no more than 5% of the surface per square meter, can include a slight dark shadow; a small amount of blemishes, rust caused by minor decoloration; oxide and paint blemishes.
Sa3 level – level equivalent to the U.S. SSPC-SP5 level, is the highest level of treatment in industry, also known as white cleanup level (or white level). Sa3 level of treatment of technical standards: the same as Sa2.5 level but 5% of the shadow, blemishes, rust, etc. had to exist.
[Classification of sandblasting machine]
Sandblasting machine is the most widely used products in the abrasive jet, sandblasting machine is generally divided into two categories: dry sandblasting machine and liquid sandblasting machine, and dry sandblasting machine can be divided into two categories: inhalation type and press-in type.
A. Inhalation type dry sand blasting machine
1. General composition: a complete inhalation dry sand blasting machine is generally composed of six systems, namely, structural system, media power system, piping system, dust removal system, control system and auxiliary system.
2. Working principle: Inhalation dry sand blasting machine is powered by compressed air, through the high-speed movement of airflow in the gun to form the negative pressure, the abrasive through the sand tube. Sucked into the gun and shot out by the nozzle, sprayed to the processed surface, to achieve the desired processing purpose. In the inhalation dry sandblasting machine, compressed air is both for.
Press-in type dry sand blasting machine
1. General composition: A complete press-in dry blasting machine work unit is generally composed of four systems, namely, pressure tank, medium power system, piping system, control system.
2. Working principle: The press-in dry sand blasting machine is powered by compressed air, and through the working pressure established by compressed air in the pressure tank, the abrasive is passed through the sand valve. Pressed into the sand tube and shot by the nozzle, sprayed to the processed surface to achieve the desired processing purpose. In the pressed-in dry sandblasting machine, compressed air is both for.
Three, liquid sand blasting machine
Liquid sand blasting machine relative to the dry sand blasting machine, the biggest feature is a good control of sand blasting process dust pollution, improve the working environment of sand blasting operation.
1. General composition: A complete liquid sand blasting machine is generally composed of five systems, namely, structure system, medium power system, piping system, control system and auxiliary system.
2. Working principle: The liquid sand blasting machine takes the abrasive fluid pump as the feeding power of the abrasive fluid, and delivers the stirred abrasive fluid (the mixture of abrasive and water) to the gun through the abrasive fluid pump. Compressed air is used as the accelerating power of the abrasive fluid and enters the gun through the air delivery pipe. Inside the gun, the compressed air accelerates the abrasive fluid entering the gun and shoots out through the nozzle, spraying it to the processed surface to achieve the desired processing purpose. In the liquid blasting machine, the abrasive fluid pump is the supplying power and the compressed air is the accelerating power.