What Is Shot Blasting?

Photo from mesblate

Shot Blasting is also known as shotblasting or wheel blasting. It is an industrial and automated process to remove metal surface scales, impurities and contaminants.

To know what is shot blasting , definition of each word is a good way to get detailed pictures.
“Shot” refers to spherical steel shots made of molten steel through an automatic process, available in different sizes and hardness. Steel grit and cut wire also characterize shots with a predominantly angular shape. All of these metallic abrasives are used as media in Shot Blasting process.
“Blasting” is a process where small angular or spherical particles are propelled at a substrate by compressed air, mechanical high-speed rotating wheels or water pumps. Compressed air blasting is categorized as sand blasting. Blasting by mechanical high-speed rotating wheels is categorized as shot blasting and wheel blasting. This process is widely used because it is efficient, economical and fast. This is key to learn what is shot blasting.

Mesblate recommends that shot blasting is an excellent method for removing rust, heat-treat scale, corrosion, old paint, flash burn and dirt. It prepares for assembly, plating, anodizing, painting, priming and coating.

Working principle is another way to figure out what is shot blasting.

Steel shots are loaded into turbine wheels in shot blasting machine. Three-phase asynchronous motors provide power for turbine wheels. Motors can be directly connected to blast turbine wheel shaft. Or motors can be connected to pully on wheel with rubber belts. Electric motor energy is converted into centrifugal force energy by rotating a turbine wheel. These shots are accelerated to reach 2950 rpm in high rotating enclosure (impeller and control cage). And then, shots are released from housing windows to form high speed abrasive stream with speed over 70 m / s.

The capacity of each wheel goes from approximately 120 kg per minute up to 600kg/min by Mesblate.These large amounts of accelerated abrasives impact on metal surface of different metals, steels, castings and fabricated work pieces. Quantity and power of blast wheels for shot blasting depend on metal work pieces to be blasted as well as required finish level, roughness and efficiency.

Several factors should be considered to reach expected cleanness and finish level. Right abrasives should be used like material, shape, density, and particle size. Sufficient abrasives stream should be covered on each square meter metal surface. Parts and work pieces are de-rusted, descaled, deburred, de-sanded or cleaned in some form. Further surface treatment, treatment and preparation can be followed, such as priming, painting, coating, hot dip galvanizing, etc…

Normally the way of transportation of the work pieces to be blasted will define the type of shot blasting machine : from simple table shot blasting machines, tumble shot blasting machines and drum shot blast machines to integrated wheel blasting machines for full series industrial manufacturers, through to roller conveyors and strip descaling systems.

1. Shot Blasting is cost-effective and time conserving way to clean metal surface. Abrasives can be reclaimed to recycle more than thousand times. New abrasives will be added for few weeks.
2. Metal surface and substrate are cleaned well and thoroughly. Compressive residual stress is released helpful to modify the mechanical properties of metals.
3. Metal surface is roughened with certain profile prepared for later machining and coating.
4. Shot blasting is Eco-friendly and healthy operation. Metallic abrasive replace silica sand which often tends to crush rapidly producing huge silica fine powder. Operator devastate lung disease exposed these silica dusts.
5. Full scope of metallic media available at Mesblate can be applied in shot blasting. Irregular shaped media can ship deep profile. Steel grits help to get slightly fine surface. Stainless and aluminum shots are used for aluminum work pieces.

Typical shot blasting abrasives include carbon steel shots, steel grits, cut wire, stainless steel shots, aluminum shots, copper shots, and zinc shots… These abrasives can be reclaimed by automated system including screw conveyor, bucket elevator and abrasive separator.

Only metallic abrasives can be used for shot blasting. Silica sands, garnet, and olive can be used. These minerals tend break up quickly in high speed wheels. And they can be recycled for continuous
blasting process.

Amount of dusts are produced during shot blasting. These dusts will contaminate blasted metal surface, accelerate spare parts wear, and pollute workshop environments. Fans extract these dusts out of blasting chamber via ventilation pipes. Dusts are captured and filtrated in dust collector by Mesblate. Clean air are released out of chimney. Pulse reverse device will clean filter periodically.

Shot blasting is normally automated blast cleaning process. One or two operators can run shot blasting machine on electric control panel. Shot blasting process will run automatically. Labors are saved and efficiency are promoted.

Unlike sand blasting, shotblasting is airless cleaning method. No compressed air get involved.
For sandblasting, air and sand mixture impact toward work pieces surface. But shotblasting use electric motor to generate kinetic abrasive energy by rotating a turbine wheel.

Shot blasting is used in almost every industry that uses metal, including metal manufacturing, foundry, shipbuilding, automotive and engineering industry, pipe and cylinder industry…

The main difference is that in the shot blasting process we use throwing wheel and in sand blasting process compressed air is used. Blasting way defines what is shot blasting.
Shot blasting: abrasive obtains velocity via the propelling wheel, which is quickly rotating in a special steel enclosure, with one side heading outlet. Shot blasting is used for cleaning steels, different profiles and welded constructions.
Sand blasting: abrasive and compressed air are mixed into the abrasive stream. These mixtures are blasted out from the blasting nozzle. Sand blasting is used in the blast rooms and blast cabinets.

• Shot blasting use blasting turbine wheel.
• Shot blasting use electric motor.
• Shot blasting use metallic abrasives.
• Abrasives can be reclaimed.
• Shot blasting is automated.

• Sand blasting use blasting nozzle.
• Sand blasting use blasting nozzle.
• Sand blasting use mineral abrasives.
• Abrasives can not be reclaimed.
• Sand blasting is manual type.