The Comparison Between Sandblasting and Shotpeening

Sandblasting and shot peening are two common methods of surface treatment,here we briefly introduce them.

 

Sandblasting:

 

Sandblasting is one surface treatment process which uses the compressed air as power to form a high-speed

jet beam,then spray the particles of abrasive onto the surface of the work-pieces at a high speed, use the strong

impact of the abrasive to finally achieve the purpose of surface cleaning or finishing.

 

Main Applications of Sandblasting:

1. Surface cleaning to remove the rust, welding slag, paint layer, etc. ;

2. Surface finishing to remove the molding sand and oxide-scale on the surface of castings, forgings or

heat-treated parts;

3. Surface pretreatment before electroplating, anodizing or painting to improve the surface roughness and

improve its adhesion;

4. Remove the burrs or directional wear-marks on the surface of the work-pieces;

5. Achieve a certain surface finish and restore the metallic luster.

 

The blasting media used in sandblasting process is mainly angular and sharp grains, such as brown fused

alumina, white fused alumina, iron sand..., but the round blasting media of ceramic beads can also be used,

that above medias will impact the surface of the work-piece to clean and increase its roughness,finally achieve

one better mechanical properties and surface finish. finer sandblasting, easy to control precision and flatness;

Sandblasting is one relatively delicate process, whose accuracy and flatness is easy to be controlled.

However, certain parts of some special work-pieces are not allowed to be sandblasted, and proper protection

must be carried out before sandblasting.

These special work-pieces includes curved teeth, internal and external spiral teeth, large internal and external

threads, etc.,then those non-sandblasted surfaces must be protected by mechanical clamps, tapes, paper tapes,

rubber plugs, etc.

 

 

Shot Peening:

Same as sandblasting,shot peening is also one process that uses compressed air as power to spray the

particles of shot peenings onto the surface of the work-pieces,achieve the purpose of surface cleaning or

surface strengthening on the surface of the work-piece.

 

The media used for shot peening is round particles without edges and corners, such as steel shots,

stainless steel shots, glass shots and ceramic shot peening.

The process of shot peening relies on the strong impact of shot media to form a strengthening layer of a

certain thickness, and a high residual stress in the strengthening layer. Due to the existence of the

compressive stress on the surface , when the work-piece is subjected to the load nucleus, the anti-stress

can be offset partially, thereby to improve the work-piece’s fatigue strength and life finally.

 

Shot peening can use metal or non-metal shot media to meet the different cleaning requirements ,it can

clean the inner and outer surfaces of complex work-pieces and the inner wall of pipe fittings.

However, when shot peening, one sufficient coverage must be ensured,it is necessary to ensure the minimum

non- shot-peened area .

While since it is difficult to check the coverage rate , people always take the required compressive stress value

as the method of controlling the shot peening intensity. That value is mostly measured in accordance with the

American SAE Standard.

 

Main Application of Shot Peening:

1. Widely used in large shipyards, heavy machinery factories and automobile factories, to remove the oxide-scale,

rust, molding sand,old paint film with a thickness of not less than 2 mm or no requirement to maintain the thickness

size and outline for medium and large metal products , as well as casting and forging parts.

2. Widely used to improve metal parts that have been used for a long time under high stress conditions, such as

compressor blades of aircraft engines, fuselage structural parts, and automotive transmission system parts.

 

Ceramic beads and glass beads are both small solid spheres that can be used for both sandblasting and shot

peening among all the blasting and peening medias. However, ceramic beads has the outstanding characteristics

of high hardness, high density and low breakage rate. When a cleaner sandblasting or shot peening environment

is required, ceramic beads can replace glass beads. Since it can provide one clean and blasting working condition

due to its low breakdown rate.

 

The size of ceramic beads used for blasting and shot peening are totally different, details sizes as below:

 

Ceramic Blasting Media	B20: 0.600-0.850mm	B120:0.063-0.125mm
	B30:0.425-0.600mm	B150:0.000-0.125mm
	B40:0.250-0.425mm	B170:0.045-0.090mm
	B60:0.125-0.250mm	B205:0.000-0.063mm
	B80:0.125-0.212mm	B400:0.030-0.063mm
	B100:0.106-0.180mm	B505:0.010-0.030mm
Ceramic Shot Peening	Z100: 100-150μm	Z150: 150-210μm
	Z210: 210-300μm	Z300: 300-425μm
	Z425:425-600μm	Z600: 600-850μm
	Z850: 850-1180μm	/
Remark: Special specification can be customized.