What is Sand blasting?
Sand blasting is the process of scrubbing the surface of any material by application of a propelling jet of abrasive substances (generally used sand) in order to smoothen or roughen the surfaces by filling layer of it.
The abrasive materials used must be more tough and hard than the material layered over the surface of the surface. As we know sand contains a crystal of quartz crystal & feldspar, which is number as 7 and 6 respectively Mohr’s scale, and have very good abrasive property.
Sometimes synthetic silica, carbon materials, silicon carbides, garnet are also additionally added in order to improve the quality of the abrasion.
Sanding is the simplest and traditional method used before sandblasting, in which the sand dust adheres to high-quality paper or fiber, and those materials are scrub against the surface either by hand or rotating mechanical equipment kike grinder. Thus, one can simply understand sandblasting as the continuous stream of the sand flint driven in air.
Sanding is a traditional and time-consuming process for the big and sophisticated substance or material having different shapes. Thus the concept of sandblasting was introduced with patent right in the US in 1870. The concept of sandblasting is generally adopted from the natural phenomena of Aeolian erosion caused by dust in the desert area.
The sand blasting consists of the mechanical equipment which continuously blows a jet of the mixture of sand and air in high compressive pressure through the nozzle made up of high-quality material like boron carbide so that the mix of sand and air cannot erode the material of the nozzle.
Types of sand blasting equipment, depending upon mechanism they work
- Suction feeder blaster: Here the mechanism operates by siphoning action. The abrasive material is sucked upon compressed air units and discharged through nozzles.
- Pressure feed blaster: The abrasive material is stored within the equipment along with air. and then compressed or pressurized. The pressurized mix is then released or discharged with help of the nozzles and valve.
Use of sandblasting
Sand blasting is a modern and improvised version of the sanding, which sole purpose is to modify the surface strata of material whether by smoothing it to give polish surface or by roughing it or filling it is a very simple and effective way in less time. Sand blasting can be applied to various materials like wood, metal, stone(having less hardness scale than sand material), painting layers, plastic, synthetic carbon material, etc.
Some major uses of sandblasting are;
- Sand blasting is often done before the application of paint. The rust, dust, and unwanted layers of paints can be easily removed with a jet of propelling sands. Sandblasting not only removes such layers but also roughen the surface by creating microscopic ridges and serrated lines because of which paint can easily form good adhesive bonding.
- Sandblasting with finer graded sands are also used to smoothen the surface of the piece of work of wood, metal plastic, resins, etc. which to give a shiny and smooth surface.
- It is very useful for the sophisticated and complicated geometry of materials or equipment where hand sanding is extremely difficult.
- Sandblasting corrodes the layer of material. So with help of sandblasting and different rough grade of sand, one can simply file the unnecessary surface material over the surface and also can provide smoothen shapes. However, the filing must be only within the limit of 2-5mm only.
Thus they are used for chamfering and rounding of the structures.
During welding many unwanted extra welded material are adhered to the surface. So with the help of the sandblasting with small nozzle they can be targeted to remove easily.
- Sand blasting is very useful to create the clearance space between the shaft and holes and two intersecting joints as it a file or corrode the layer evenly overall surface.
How to perform sand blasting?
The sandblasting equipment simply includes three major working parts or components, the blasting media cabinet, the air compressor unit, and the discharging nozzle. Beside some sandblaster equipment for minute works for the small dedicated substance or part, the sandblasting equipment is also provided with sandblasting cabinet and dust collector.
The sand or the abrasive material is first filled in the collecting compartment of the sandblasting equipment. Then with help of the air compressor such sand (sand mix with air, depends upon the type of the sandblasting equipment operating mechanism) are forcefully propelled in form of the strong jet through the nozzles.
The head of the nozzle with a switch nearby is held by the operator and he/she applies the jet over the surface where the sandblasting operation is required to be performed.
The operator must have a specially designed dress and gloves to perform the sandblasting for his/her safety. And the operator must apply a jet of propelling sand evenly over the surface else there may be a problem of undulated surfaces over the sandblasted area.
Advantages of sand blasting
- It is a very easy, efficient, and time-saving method than sanding.
- The abrasive action of sandblasting is more even
- The sandblasting can be easily used to the corners and the sophisticated geometrical areas without much effort
- Sandblasting is a very powerful method so can even remove tough layers of concrete, slag of welded material, and highly adhered paint colors (like in the car)
- Sandblasting can be easily performed. Moreover, the abrasive material used is sand which is abundantly available in many parts of the world.
Sand blasting have high efficiency , however it has several disadvantages to use. Come of them are,
- Sand blasting over the smooth area and hardened area like glass are not useful. As it is ineffective to such surface ad moreover they create a scratch over such a smooth surface.
- The residual dust remnants after sand blasting can cause pollution in the air. And also causes difficulty in breathing. the operator associated with it may have Respiratory Track Infectious disease.
- The use of silica might cause a siliceous hazard as the silica sand breaks easily causing a large amount of minute dust.
- There is a probability of harm by the rebounded abrasive material near the area. Thus the protective casing is used for small work however cannot be used for large voluminous works.
- The equipment might not be easily available and accessible. Moreover, it is not economic for small projects.
- High precaution measures are to be taken by operators.
I hope this article remains helpful for you.
Happy Learning – Civil Concept
Civil Engineer – Rajan Shrestha