How to control roughness in sandblasting processing in Dalian?

Dalian sandblasting is a surface treatment process that uses high-speed abrasive to impact and cut the surface of workpieces, and is widely used for surface treatment of materials such as metals, plastics, and glass. Its purpose is to remove surface oxide layer, burrs, dirt, increase surface roughness, improve coating adhesion, or achieve specific surface texture effects. Controlling surface roughness is a key technical requirement in sandblasting, as roughness directly affects the functionality and aesthetics of the workpiece.

1. Selection of abrasives

Abrasive is one of the core elements of sandblasting processing, and its type, particle size, shape, and hardness directly affect surface roughness.

Abrasive types: Commonly used abrasives include steel grit, glass beads, alumina, silicon carbide, etc. The hardness and cutting ability of different abrasives vary. For example, steel grit has a high hardness and is suitable for metal surface treatment, which can produce a large roughness; Glass beads have lower hardness and are suitable for surface polishing or slight roughening treatment.

Abrasive particle size: The larger the abrasive particle size, the higher the surface roughness after sandblasting. For example, using abrasives with 20-40 mesh (coarse sand) will result in a rougher surface, while using abrasives with 80-120 mesh (fine sand) will result in a smoother surface. Choosing the appropriate particle size is the key to controlling roughness.

Abrasive shape: The shape of the abrasive also affects the roughness. Sharp abrasives, such as angular alumina, can more effectively cut surfaces and produce higher roughness; Circular abrasives (such as glass beads) are mainly used for polishing and slight roughening.

2. Sandblasting pressure

Sandblasting pressure is another important factor affecting roughness. The greater the pressure, the stronger the impact force of the abrasive on the surface of the workpiece, the more obvious the cutting effect, and the higher the roughness.

High pressure sandblasting: suitable for workpieces that require high roughness, such as coating pretreatment on metal surfaces. However, excessive pressure may lead to excessive damage or deformation of the surface.

Low pressure sandblasting: suitable for workpieces that require lower roughness, such as surface treatment of precision parts. Low pressure sandblasting can reduce the impact on the surface and achieve a smoother surface.

In practical operation, it is necessary to choose the appropriate sandblasting pressure based on the material, thickness, and roughness requirements of the workpiece.

3. Sandblasting distance

Sandblasting distance refers to the distance between the nozzle and the surface of the workpiece. The closer the distance, the more concentrated the impact force of the abrasive, and the higher the surface roughness; The farther the distance, the more dispersed the impact force of the abrasive, and the lower the surface roughness.

Close range sandblasting: suitable for workpieces that require high roughness, but attention should be paid to controlling the sandblasting time to avoid excessive surface damage.

Long distance sandblasting: Suitable for workpieces that require lower roughness, it can achieve a more uniform surface treatment effect.

4. Sandblasting angle

Sandblasting angle refers to the angle between the direction of abrasive spraying and the surface of the workpiece. The cutting effect of abrasive on the surface varies depending on the angle.

Vertical sandblasting (90 °): The abrasive has a strong impact on the surface, which can produce high roughness but may lead to uneven surface.

Tilt sandblasting (30 ° -60 °): Suitable for workpieces that require lower roughness, it can achieve a more uniform surface treatment effect.

In practical operation, it is necessary to choose the appropriate sandblasting angle according to the shape and roughness requirements of the workpiece.

5. Sandblasting time

Sandblasting time refers to the duration of the abrasive's effect on the surface of the workpiece. The longer the time, the more sufficient the cutting effect of the abrasive on the surface, and the higher the roughness.

Long term sandblasting: suitable for workpieces that require high roughness, but attention should be paid to controlling the sandblasting pressure and time to avoid excessive surface damage.

Short term sandblasting: Suitable for workpieces that require lower roughness, it can achieve a smoother surface treatment effect.

6. Material of workpiece

The material of the workpiece can also affect the roughness after sandblasting. The hardness, toughness, and surface properties of different materials vary, and their response to abrasives is also different.

High hardness materials (such as steel) require higher sandblasting pressure and coarser abrasives to achieve the desired roughness.

Low hardness materials (such as aluminum): require lower sandblasting pressure and finer abrasives to avoid excessive surface damage.

7. Sandblasting equipment

The performance of sandblasting equipment can also affect the control of roughness. For example, the diameter of the nozzle, the pressure and flow control accuracy of the sandblasting machine, etc. can all affect the sandblasting effect.

Large diameter nozzle: suitable for workpieces that require higher roughness, capable of spraying more abrasives.

Small diameter nozzle: Suitable for workpieces that require lower roughness, it can more accurately control the sandblasting effect.

8. Surface roughness detection and adjustment

During the sandblasting process, it is necessary to regularly check the surface roughness to ensure compliance with design requirements. Common detection methods include roughness meters, profilometers, etc. If the roughness does not meet the requirements, optimization can be achieved by adjusting parameters such as abrasive, pressure, distance, angle, etc.

Controlling the roughness of sandblasting requires comprehensive consideration of multiple factors such as abrasive, pressure, distance, angle, time, material, and equipment. In practical operation, it is necessary to select appropriate process parameters based on the specific requirements of the workpiece, and ensure that the surface roughness meets the design standards through testing and adjustment. Through scientific and reasonable control, sandblasting can provide ideal surface treatment effects for workpieces and meet the needs of different application scenarios.