In modern manufacturing, forged parts serve as the foundation for numerous mechanical components, and their surface quality has a crucial impact on the performance of the final product. As a highly efficient surface treatment process, sandblasting plays an indispensable role in the surface treatment of forged parts. This article provides an in-depth discussion on the application of sandblasting in forged part surface treatment, helping you fully understand the advantages of this process, key operational points, and comparisons with other surface treatment methods.
Before exploring the application of sandblasting in the surface treatment of forged parts, let us first understand the basic principles and characteristics of sandblasting and shot blasting.
Shot blasting uses the high-speed operation of mechanical equipment to eject steel shots of specific particle sizes (such as cast iron shot, cut wire shot, cast steel shot, stainless steel shot, etc.) through the centrifugal force generated by the blast wheel, causing them to collide violently with the workpiece and thereby remove rust from the steel surface.
Cast steel shot and cast iron shot are formed from molten iron that is sprayed and rapidly cooled. The resulting iron shots have particle sizes of 0.8–5 mm. Their surfaces are smooth and round, and although they are relatively inexpensive, their durability is slightly lower. During repeated impacts in the blasting process, these shots gradually break apart, turn into fine dust, and are carried away by the dust removal system.
Cut wire shot is produced by cutting discarded steel wire ropes into small segments of about 2 mm each. These segments have sharp edges, achieve better rust removal performance, and are less prone to breaking during use, which gives them a longer service life. However, their higher cost must be taken into account. After shot blasting, the resulting surface texture tends to be rougher.
Sandblasting uses high-pressure air to propel quartz sand onto the workpiece surface to remove rust. Quartz sand is widely sourced, including river sand, sea sand, steel sand, and artificial sand.
This method has low cost, but it produces considerable environmental pollution and relies entirely on manual operation. The surface roughness after sandblasting is small, making it difficult to achieve the required friction coefficient for certain applications. Additionally, sea sand must be de-salted before use to avoid causing corrosion problems.
As a surface treatment process, sandblasting offers numerous advantages in handling forged parts, making it an important step in improving forged part quality.
Sandblasting effectively removes oxide scale, rust, and other impurities from the surface of forged parts. It also achieves a certain level of surface roughness, which significantly enhances the adhesion of subsequent coatings such as paint and protective layers. This is critical for improving corrosion resistance and extending the service life of forged parts.
For instance, in the automotive manufacturing industry, steel plates that undergo sandblasting exhibit significantly better coating adhesion, leading to improved appearance quality and corrosion resistance.
Sandblasting accelerates abrasive particles to high speeds using compressed air. As they strike the forged surface, they cause slight plastic deformation, forming a layer of compressive stress. This compressive stress layer offsets tensile stress generated during service. As a result, the fatigue strength of forged parts is noticeably improved.
For example, shaft components subjected to alternating loads can achieve far greater fatigue life after sandblasting. This enhancement not only extends equipment lifespan but also reduces maintenance and operational costs.
Compared with shot blasting, sandblasting offers superior flexibility when dealing with forged parts that have complex shapes. Since sandblasting uses compressed air to deliver abrasive particles, it can easily reach all areas of the workpiece, including grooves, corners, narrow gaps, and curved surfaces that shot blasting equipment may not adequately reach.
In the aerospace industry, many engine components and structural parts feature intricate geometries. Sandblasting is especially important in these cases because it ensures that every surface meets the extremely high-quality requirements demanded in aviation engineering.
While sandblasting does generate dust, modern sandblasting equipment is equipped with effective dust-collection systems that reduce pollution and improve the working environment. Moreover, quartz sand and other abrasives are inexpensive and can be recycled after separation and filtration, which lowers overall production costs.
For this reason, sandblasting remains a highly cost-effective surface treatment process and is especially suitable for large-scale forging production lines.
To fully realize the advantages of sandblasting and ensure optimal results, it is necessary to pay attention to several important operational factors during the implementation process.
Abrasive selection is a crucial factor that significantly influences sandblasting results. Different abrasive materials differ in hardness, shape, size, and cost, and these characteristics directly affect cleaning performance.
Common abrasives used for forged parts include:
Quartz sand: low cost, widely available, suitable for general rust removal.
Brown fused alumina: high hardness, high cleaning efficiency, but more expensive.
White fused alumina: even higher hardness, suitable for precision surface requirements.
When selecting abrasives, factors such as the forged material type, initial surface condition, and coating adhesion requirements must be considered.
Sandblasting parameters such as pressure, distance, angle, and time must be strictly controlled.
Pressure determines the impact energy of abrasive particles. Excessive pressure can damage forged parts, while insufficient pressure may fail to produce satisfactory cleaning results.
Distance and angle must be adjusted according to the shape and size of the forged part to ensure even coverage and uniform cleaning.
Sandblasting duration must be appropriate. Excessive time may over-clean or damage surfaces, while insufficient time may leave rust or scale behind.
In practice, optimal parameters are determined through testing and experience.
Advanced sandblasting equipment offers more precise parameter control, higher abrasive recycling efficiency, and better dust removal performance. These improvements help ensure consistent quality and reduce environmental impact.
Operators must receive proper training so they understand:
Equipment operating procedures
Safety precautions
Sandblasting principles
Adjustment techniques
Troubleshooting methods
Skilled operators can ensure more stable production and superior surface treatment results.
In addition to sandblasting and shot blasting, surface treatment methods such as pickling and electrochemical rust removal are also used in industry. Understanding their differences helps select the most suitable method for forged part treatment.
Both sandblasting and shot blasting are widely used, but they differ in several ways:
Shot blasting is best for regular-shaped forged parts and is highly efficient. It produces less dust and is ideal for mass production.
Sandblasting is better suited for complex shapes and offers greater flexibility in cleaning difficult surfaces. Additionally, it produces better surface roughness, improving coating adhesion.
In shipbuilding, for example, shot blasting is often used for steel plate pretreatment, while sandblasting is used on formed hull structures to remove old paint and rust.
Pickling removes rust via chemical reactions using acidic solutions. While efficient, it generates acidic wastewater and carries the risk of over-corrosion. In contrast, sandblasting is a purely physical process:
It does not produce chemical wastewater
It gives better control over surface roughness
It provides stronger coating adhesion
As environmental regulations become stricter, sandblasting is increasingly replacing pickling in many industries.
Electrochemical rust removal uses electrolysis to remove rust and contaminants. It is gentle and causes no mechanical damage, but:
Equipment is expensive
Efficiency is low
The process is slow
It is unsuitable for batch production
Sandblasting, on the other hand, offers lower equipment cost, high efficiency, and better adaptability, making it more suitable for mass production.
Electrochemical treatment is often used only for small batch, high-precision forgings, while sandblasting remains the mainstream choice for large-scale manufacturing.
As a highly efficient surface treatment process, sandblasting offers broad application prospects in forged parts processing. It effectively removes oxide scale, rust, and impurities, enhances surface roughness and coating adhesion, improves surface stress conditions, and significantly boosts fatigue and wear resistance. By selecting the right abrasives, optimizing process parameters, and adopting advanced equipment, companies can maximize the advantages of sandblasting and meet the demanding surface quality requirements of various industries. With the continuous development of environmental protection technologies, automation equipment, intelligent control systems, and multifunctional sandblasting technologies, sandblasting will play an increasingly important role in future manufacturing, contributing to better product quality and higher production efficiency.
