Shot Blasting Guide: Principle, Requirement, Advantage & Process

Mechanical surface treatment methods sometimes go by the label “shot blasting.” Sandblasting and shot blasting are two methods that accomplish the same thing. The shot blasting procedure is a type of cold treatment that may be broken down into two distinct phases: cleaning and strengthening. In this shot blasting guide, we talk about the shot blasting principle, requirement, advantage, and process.

 

Shot Blasting Guide: Principle, Requirement, Advantage & Process

The purpose of shot blasting cleaning is, as suggested by its name, to improve the surface’s aesthetic quality by removing contaminants such oxide skin. When using shot blasting strengthening, a high-velocity moving shot (60-110m/s) flow is constantly impacted on the surface of the reinforced workpiece, causing the following changes to the target surface and surface layer (0.10-0.85mm) throughout the cyclic deformation process: Three things happen:

(1) The microstructure is altered;

(2) Residual compressive stress is injected into the outer layer of the material due to non-uniform plastic deformation, and residual tensile stress is created in the inner surface layer;

(3) The external surface roughness is altered (RaRz). Impact: It can lengthen the fatigue life of materials and components, make them less prone to fatigue failure, plastic deformation, and brittle fracture, and increase their resistance to these phenomena.

 

The Basics of the Shot Blasting Method

Shot (steel fired) is mechanically shot onto the working surface at high speed and at a specified angle, causing the shot to contact the surface with great velocity. Shot material can be recycled indefinitely thanks to cutting-edge technology that allows it to automatically circulate within the equipment thanks to the vacuum negative pressure and rebound force of the supporting vacuum cleaner. Shot and cleaned impurities are both recovered via the air flow cleaning of the supporting vacuum cleaner. The machine’s dust extractor allows for clean, pollution-free building, which benefits both productivity and the environment. Shot strengths and surface treatment effects may be modified during machine operation by changing particle size and shape selections and walking speed controls.

 

Essentials of the Shot Blasting Technique
Different shot intensities and surface treatment effects may be achieved by modifying the walking speed of the machine and fine-tuning the particle size and form of the shot used in the shot blasting process. Three metrics are used to regulate the surface condition following treatment with the shot blasting technique and equipment. Shot size, shape, equipment speed, and flow rate may all be customized. All three of these factors interact with one another to produce various treatment effects and guarantee the desired surface roughness following shot blasting. For instance, the surface of C50 concrete may be treated with S330 steel shot at a flow rate of 10A to produce a roughness of 90; the flooding layer can be removed from an asphalt surface to achieve a roughness of 80; and the cleanliness requirement of SA3 can be attained while processing steel plates.

Traditional components of shot blasting Steel shot, aluminum shot, ceramic powder, steel sand, walnut sand, corn cob, glass bead, resin sand, plastic sand, and a wide variety of other materials are commonly used as shot blasting media.

 

Shot Blasting Features

1.Shot blasting’s superior efficiency, practicality, cost-effectiveness, and ease of cost and efficiency management;

2.Shot blasting’s ease of use and cost-effectiveness; and it’s not as malleable or precise as shot peening; There will be dead ends during shot blasting, which makes the total number of dead spots

3. Typically, batch processing is applied to workpieces that are uniform in both shape and surface.

The goal of shot blasting is to reduce the amount of residual high tensile stress on the surface of the components, increase their fatigue strength by generating compressive stress, and so avoiding failure.

In most cases, shot blasting is unnecessary since the operating temperature of steel components is greater than 260 °C and the operating temperature of aluminum components is greater than 170 °C. When the shot blasting pressure stress is reduced due to excessive usage temperature, the intended result is lost.

 

The steps involved in a shot blast are as follows:

Determine which sort of pill to use:

The typical hardness of cast steel shot is between 40 and 50 on the Rockwell scale. Hard metals can have their hardness enhanced to the HRC57–62 range by machining. Shot made from cast steel is durable and has many applications. It has a lifespan multiple times that of cast iron shot.

Cast iron shot has a hardness of HRC58–65, making it brittle and easily broken, but also has a short service life and so is commonly utilized. Its primary application is in conditions calling for a high level of shot blasting power.

 

Size selection for shot blasting:

Shot blasting particles are typically between 6 and 50 meshes in size. If you need to blast with more force, you’ll need bigger shot blasting particles.

The diameter of the shot blasting should not be larger than half the inner diameter of the groove, since this choice is also constrained by the geometry of the shot blasting elements. The higher the shot size, the greater the impact energy and the greater the intensity of the shot blasting; nevertheless, the shot blasting coverage decreases. Therefore, it is beneficial to minimize shot blasting size as much as feasible under the assumption of generating necessary shot blasting power. Choosing the Hardness of Shot Blasting
Shot blasting, in general, should have a higher hardness than the components it’s used on. When the shot blasting hardness value is higher than the component hardness, the shot blasting strength is insensitive to changes in the hardness value. However, if the shot blasting hardness value is decreased, the shot blasting strength will be weakened.

 

Determine the Rate of Injection
In other words, if you increase the shot blasting speed too much, the shot blasting crushing quantity will grow. Intensified shot-firing leads to more ammunition being used.

 

Modify the inclination of the injection
Shot blasting is most effective when the target is vertical, hence this is the most common orientation in which to do it. Shot blasting speeds or shot blasting sizes should be raised proportionally if shot blasting is required to be performed at a limited angle owing to the constraint of component shape.

 

The overwhelming volume of shot bursting
Since fractured shot blasting has a low shot blasting strength, it requires regular removal to maintain a shot blasting integrity of at least 85%.

 

Seconds before blasting off
The effectiveness of the shot blasting process on the workpiece determines the amount of time required for the shot blasting process. The goal of the principle is to develop sufficient shot blasting strength. (often within the span of 30 minutes)