1. HOME
  2. What is Wet Blasting?
  3. What is Blasting?

What is Blasting?

What is Blasting?

Blasting is a surface processing method in which countless abrasive particles are sprayed, thus colliding with the workpiece to roughen, grind, or polish the surface.

Blasting is generally a dry process. However, depending on the method, it is classified into several types such as Sand Blasting, Blower Blasting, and Shot Blasting. It is also used for various purposes such as rust removal, cleaning, and polishing. Especially well-known applications include glass craft patterning and lettering of tombstones.

This page provides an overview of the blasting process in general, its features, types, applications, general merits and demerits, and Wet Blasting.

What is blasting?

Incidentally, blasting is a kind of "free abrasive processing".
There are two types of processing using abrasives. One is "fixed abrasive processing" that uses tools with fixed abrasives such as belt grinding, tape grinding, and sandpaper, as well as polishing and lapping. The second is "free abrasive processing" in which the abrasive is mixed with a liquid and the surface is polished or ground in a state where it moves freely, and the blasting process corresponds to the latter.

The Origin of Blasting

It is said that the origin of the blasting method was around 1870 when a U.S. engineer named B.C. Tillman invented a device for spraying emery sand and named it "sandblasting".
Tillman is said to have come up with this invention after noting that the window glass fogged up after a sandstorm in a seaside town.

The Origin of BlastingVarious Abrasives

Blasting Characteristics

Blasting, in which abrasive particles directly hit against an object to process it, has various characteristics as shown below.

Physical Processing

All methods of blasting are physical processes that produce effects by physically hitting, scraping, or rubbing an object, and do not use chemicals or organic solvents.

Constant Processing Force

In blasting, which is free abrasive processing, no further external force is applied to the particles once they are sprayed or blasted.
Therefore, the processing force is determined by the mass, speed, and shape of the particles at the time of blasting, and processing is performed with a constant force within that range.

The processing surface has no directionality.

When a large number of particles are projected with a constant force and collide with the object, a large amount of unevenness corresponding to the size of the particles used is formed on the surface of the object.
This unevenness does not generate streaks like buffing or lapping, resulting in a non-directional, random uneven surface.

Effects change depending on type of particle selected

By changing the material, size, shape, impact speed, mass, etc. of the particles, blasting can achieve various processing effects.
For example, polygonal particles give you grinding effects and such, and with spherical particles you can get peening effects and such.

It can handle any type of material

All blasting methods are physical methods in which the abrasive material is directly hit against the object to be processed, so processing is possible regardless of the material of the object.
A wide variety of materials can be processed, including metals, ceramics, glass, stone, plastic, and wood.

Types of Blasting

Blasting can be broadly divided into two types: dry blasting and wet blasting, depending on the environment in which the particles are used.
Dry blasting includes sand blasting, blower blasting, and shot blasting, while wet blasting includes wet blasting and wet shot blasting.
Particle acceleration methods can also be classified into two types: mechanical and pneumatic.

Blasting Classifications

  Dry Type Wet Type
Air Type
  • Sandblasting
  • Blower Blasting
  • Suction Blasting
  • Dry Ice Blasting
  • Wet Blasting
Mechanical Type
  • Shot Blasting
  • Wet Shot Blasting

Sandblasting

Dry Type/Air Type

Sandblasting is a blasting method that uses compressed air from a compressor as energy for accelerating particles.
Generally speaking, more often blasting refers to sandblasting.

Water is not used and only particles are accelerated by compressed air for spraying.
They are separated by the difference in acceleration method: One is the "suction type," which uses the force of compressed air to suck and project the particles into the nozzle, and the other is the "direct pressure type," in which the particles in the pressurized tank are mixed and pressurized by air and projected.

Previously, it was called "sand" blasting because it used sand as an abrasive. However, today it uses ceramics such as alumina (aluminum oxide), as well as glass, plastic, metal and walnut powder as abrasives.
Sandblasting is often used for glass craft patterning and lettering of tombstones.

Sandblasting

  • Since various particles can be used, it can be applied to various applications
  • Pressure adjustments are easy, and it can high-precision processing.

×

  • If there is oil or moisture on the surface to be treated, it must be degreased and dried beforehand
  • Projected abrasives are easily scattered

Blower Blasting

Dry Type/Air Type

This is a blasting method that uses a fan called a blower instead of compressed air to project or accelerate particles.

A blower has a lower pressure and weaker acceleration than that of compressed air from a compressor, and the processing is softer. However, it does not require a compressor that consumes a lot of energy, so it saves energy and keeps processing costs low. It is suitable for soft processing of large areas.。

Blower Blasting

  • No compressor needed, thus saving energy and cost.
  • It specializes in soft processing.

×

  • Due to its weak processing power, it is not good at heavy processing such as deburring and grinding.
  • High-precision processing is difficult.

Suction Blasting

Dry Type/Air Type

In this blasting method, particles are sucked in while the processing area is completely sealed, and the abrasive material is placed in the air flow to scrape the surface of the object.

Since a blower (fan) is used for suction, there is no need for a compressor, and the cost is low.
Since no abrasive material is sprayed, no dust is generated and work can be performed in a clean environment.
By placing an abrasive at the inlet of the pipe and sucking it from the exit, the inner surface can also be processed.

Suction Blasting

  • No compressor is needed, thus saving energy and cost.
  • Inner surface processing of pipes, etc. is possible.

×

  • Due to its weak processing power, it is not good at heavy processing such as deburring and grinding.
  • High-precision processing is difficult.

Dry Ice Blasting

Dry Type/Air Type

Among sandblasting, those that use dry ice pellets as an abrasive are called dry ice blasting.

Since the projected dry ice changes to a gas after colliding with the object, there is no concern about particle residue on the surface.
Also, there is no need to dispose of the used particles.

Dry Ice Blasting

  • Because the colliding dry ice vaporizes, there is no concern of particle residue.
  • Abrasive waste is not generated

×

  • The application is limited to soft processing.
  • Dry ice management is required and is costly

Shot Blasting

Dry Type/Mechanical Type

In this method, an impeller is rotated by a motor, and its centrifugal force is used to accelerate and spray the particles.

The particles used are often called blasting materials. And mainly metal abrasives such as steel, stainless steel, aluminum and copper are used.
In order to suppress scattering during spraying, particles must have a certain size and mass, and steel balls of about 1 mm are mainly used.
Abrasive material is projected over a wide area, so it is used for large-area and large-volume processing.

Shot Blasting

  • No compressor is needed, thus saving energy and cost.
  • A large amount of particles can be projected over a wide range, and uniform processing of large areas is excellent.

×

  • Adjustment of the processing force is difficult, making it difficult to achieve high-precision processing.
  • Only a few types of abrasives can be selected, and processing is limited.

Wet Blasting

Wet Type/Air Type

It is also known as "liquid honing". This is a wet blasting method in which a mixture (slurry) of water and an abrasive is accelerated by compressed air and sprayed.

Since the abrasive is always mixed with water, it does not scatter during spraying, even microparticles as small as a few microns in size, which cannot be handled by dry-type processing, can be used.
The scraped off dirt and sprayed particles are quickly washed away by the water. As a result, the surface can be processed and cleaned at the same time. Compared with the dry type, very little abrasive remains, which is a main feature of this method.

Wet Blasting

  • A wide range of particle sizes can be used, and precise to heaving processing can be done.
  • Processing and cleaning can be done simultaneously

×

  • It cannot process parts that cannot get wet.
  • Abrasives floating on water cannot be used

Wet Shot Blasting

Wet Type/Mechanical Type

This is a mechanical wet blasting method that sprays using an impeller and equipment is currently being developed by our company for practical use.

As with shot blasting, no compressed air is used, so no compressor is required. This is a next-generation blasting method that combines the characteristics of shot blasting, which can project particles over a wide area and can process large areas, and wet blasting, which allows for fine processing using very fine particles while doing cleaning and processing silmutaneously.

Wet Shot Blasting

  • No compressor is needed, thus saving energy and cost.
  • A wide range of particle sizes can be used, and precise to heavy processing can be done.

×

  • It cannot process parts that cannot get wet.
  • New information is not available because it is currently under development.

Blasting Applications

Although the application differs depending on each method, such as the strength of processing force and the difference in processing methods, this section will explain the applications in which the blasting method is generally used.

Rust Removal

The so-called "rust" that occurs on the surface when metal reacts with oxygen and moisture can be removed instantly without using chemicals.
Since blasting is a physical process, it is characterized by its ability to remove rust regardless of the material. So not just from steel, but also from aluminum, copper, and such.

Rust Removal

Die Cleaning

For the purpose of mass-producing industrial products, dies are used to create molds, and then materials such as metal, resin, and rubber are poured into them to form parts. So the dirt or grime such as mold release agents and molding material residue that adheres to the inside of this die can be removed.
Because fine particles can enter the gaps, even objects with complex shapes can be processed and the dirt removed.

Die Cleaning

Satin Finish

It is possible to form countless fine irregularities called "textures" on the surface of metals, resins, and other materials. By changing the size, shape, or material of the particles used, it is possible to create a variety of textures.
The purpose of this textured processing is to achieve the anchor effect which improves adhesive strength, adds patterns, and improves wettability.

Satin Finish

Deburring

Protrusions that occur when processing metals, resins, etc., and those that protrude from the joints of dies and harden during molding are called "burrs". Burrs cause various problems such as injury during product use and deterioration of quality. Therefore, they are removed by blasting if necessary.
Even burrs in small areas that are difficult to reach can be removed by blasting, thanks to its features of constant processing force and non-directionality.

Deburring

Paint Stripping

It is used to remove or strip paint from the surface of the object.
One of the features of blasting is that it can do this removal regardless of the material of the workpiece, unlike chemical or heat treatments.

Paint Stripping

Oxide Scale Removal

It is also used to remove "black scale" or "oxidized scale", also known as mill scale, that occurs on the target surface during the heat treatment process, such as the annealing of steel bars.

Oxide Scale Removal

Shot Peening

By colliding spherical particles against the surface of the target metal at high speed, compressive residual stress is applied, causing work hardening and plastic deformation that is called peening.
This peening improves the wear resistance and fatigue strength of the target workpiece.

Shot Peening

Polishing

Normal blasting scrapes the target surface to form a fine unevenness. However, there are also processing methods that can be do polishing (smoothening) instead of making holes.
In addition, by using a special abrasive suitable for this purpose, it is possible to eliminate unevenness on the surface and create a glossy mirror-like surface.

Polishing

Benefits of Blasting

It can handle any type of material

Blasting is a physical processing method that processes by colliding particles on the surface, so unlike chemical processing, processing can be done regardless of the material of the target object.

Non-directional uneven surface

Since the processing force is constant, directional scratches such as thosed caused by brushes or buffers do not occur, and a uniform unevenness with no directionality can be achieved.

Wide range of processing effects

Although it depends on the method, different effects can be obtained by changing the particle size, shape, material, mass, etc., even with the same equipment,

Demerits of Blasting

Only the areas that the particles hit can be processed.

Because the blasting can process only the section where the particles hit directly, it is necessary to apply the particles to the entire processed surface.
As a result, the processing time increases in proportion to the size of the process area, and it is difficult to treat narrow gaps and inner surfaces of cylinders.

Wearing down of the machine

When using particles with a strong grinding force, the machine itself is scraped and worn down because the processing chamber and the flow path of the particles are also processed simultaneously with the processing of the object.
Parts must be replaced regularly due to the higher processing power and faster wear in the pipes, the spray opening, etc., which are in the path of the particles.

Sludge is generated

Grinding debris after processing and fragments of crushed abrasives are generated as sludge. In the case of dry blasting, sludge is generated as dust, and in the case of wet blasting, processing quality becomes unstable when particles are circulated. Also, disposal of this sludge is required.

Summary

In short, blasting is not suitable for each type, as it can be said that there are various types depending on the particle acceleration method, processing environment, and the particles used.
It's best to understand the characteristics of each blasting process and select the optimum processing method that suits the processing purpose.

Click here to download documents or to make inquiries

Technical data and brochure

Download

Please feel free to contact us

Contact