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Detailed introduction of sandblasting rust
removal technology knowledge
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.
Sandblasting precautions]
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.
【Cleaning grade
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.
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