Select the shot blasting machine according to the type of casting
Selecting a shot blasting machine based on the type of casting is a systematic project that requires comprehensive consideration of multiple factors. The right choice ensures high efficiency, good cleaning quality and low cost. If the wrong choice is made, it may damage the castings, fail to clean thoroughly and result in high costs.
The following provides you with a clear choice logic and specific suggestions:
Step 1: Core Considerations (Selection Basis)
Casting material and hardness:
Gray cast iron and ductile iron: Shot blasting is the most commonly used for cleaning, and they have moderate hardness.
Steel/alloy steel castings: With high hardness, more wear-resistant shot blasting materials and equipment structures need to be selected.
Non-ferrous metals such as aluminum alloys, magnesium alloys, and copper alloys: They are soft in texture and prone to deformation. The ejection force and shot material must be strictly controlled (steel shot is prohibited; stainless steel shot, ceramic shot, glass beads, etc. are usually used), and the equipment speed should be adjustable.
Stainless steel castings: To prevent iron contamination, stainless steel shot or shot of the same material should be used.
Casting dimensions, shapes and weights:
For large-sized/heavy parts (such as machine tool beds, large valves) : Choose through-type/roller conveyor type shot blasting machines or hook-type shot blasting machines (with sufficient load-bearing capacity).
For small and medium-sized/complex-shaped parts (such as automotive components, pipe fittings, gears) : The crawler type or hook type (which can be rolled over) works well.
Long rod-shaped and shaft-shaped parts: Through type or chain suspension type is more efficient.
Thin-walled, precision and easily deformable parts: Equipment with precisely controllable ejection force, such as rotary table or special hook type, must be selected, and lightweight shot materials should be used.
Production process and batch size
For large batch sizes and high production cycle requirements: Choose equipment with a high degree of automation and continuous passage type (such as chain suspension type, roller conveyor type).
Small batch and multiple varieties: Choose equipment with good flexibility (such as hook type, rotary table type).
Cleaning requirements: Is it only necessary to remove the oxide scale/sand, or is it necessary to achieve a certain surface roughness (Sa value) to facilitate subsequent spraying?
Clear the target
Surface sanding/oxide scale removal: Regular cleaning is sufficient.
Surface strengthening (enhancing fatigue strength) : It is necessary to precisely control the shot blasting intensity and coverage rate, and the equipment parameters should be stable.
Achieve consistent surface roughness: High requirements for shot particle size and equipment uniformity.
Step 2: Compare the main types of shot blasting machines with the applicable castings
Belt-type shot blasting machine: Castings are placed in a rotating belt to roll and receive the shot. It is suitable for the batch production of small and medium-sized castings that are not afraid of collision (such as brake discs, bushings, and hardware parts). It has a good cleaning effect, automatic loading and unloading, moderate price and small floor space. It is not suitable for fragile, thin-walled or complex-shaped castings that are prone to getting stuck.
Hook-type shot blasting machine: The castings are suspended on the hook and rotate in the cavity to be shot from multiple directions. It is suitable for large and medium-sized castings with complex shapes (such as engine blocks, transmission cases, and structural components). Small batch, multiple varieties. High flexibility, no dead corners for cleaning, capable of handling heavier parts, and minimal deformation during hoisting. The production efficiency is relatively low, relying on manual labor or auxiliary hangers.
Through-type shot blasting machine: Castings are placed on roller tracks or conveyor belts and pass through the shot blasting area at a constant speed. It is suitable for plate-shaped, long rod-shaped and flat castings (such as steel plates, profiles, brake drums). Continuous mass production. It features a high degree of automation and extremely high efficiency, and can be seamlessly integrated with production lines. The equipment is large and expensive, and it has limitations on the shape of the workpiece (it needs to pass through smoothly).
Rotary table shot blasting machine: The casting is fixed on the working rotary table and rotates slowly to receive the shot. It is suitable for flat disc types, gear types, and precision castings that are afraid of collision (such as turbine discs and flange discs). The workpiece deformation is small, the cleaning is uniform, and it is easy to achieve automation. The loading capacity at one time is limited and the production efficiency is moderate.
Suspension chain shot blasting machine: Castings are suspended on a continuously moving suspension chain and pass through the blasting chamber. It is suitable for a large number of medium and small-sized castings (such as those for automobiles and motorcycles). Suitable for production assembly lines. Extremely high production rhythm, full automation, and the lowest labor intensity. The design of tooling fixtures is complex, and the equipment cost and maintenance cost are high.
Drum type shot blasting machine: Castings are cleaned by rolling and tumbling along with the rotation of the sealed drum. Suitable for small-sized castings that are not afraid of collision (such as standard parts and malleable iron parts). The structure is simple, the cost is low, and the cleaning effect is acceptable. It is noisy, inconvenient to load and unload, and prone to damaging workpieces. It has gradually been replaced by crawler types.
Step 3: Decision-making Process and Key Points
Clarify the requirements
List your leading products (type, size, weight, material).
Determine the annual output/daily processing capacity (tons or pieces).
Clearly define the surface quality requirements after cleaning (such as Sa2.5).
Evaluate the spatial layout and logistics (feeding and discharging directions) of the workshop.
Preliminary matching model:
Based on the above table and in combination with the characteristics of your castings, narrow down to 1-2 possible models.
For instance, when manufacturing automotive aluminum alloy transmission cases (medium-sized, complex, and soft materials), the preferred choice is the hook-type shot blasting machine (capable of gentle handling), and it is strictly equipped with stainless steel shot or ceramic shot.
Key details confirmed
The number and layout of shot blasting machines: Determine the cleaning efficiency and uniformity. Complex parts need to be arranged from multiple angles.
Dust removal system: The casting has a high sand content and must be equipped with a high-efficiency and large-capacity dust collector (pulse reverse blowing type is recommended), which is crucial for environmental protection and indoor visibility.
Separator: A good separator can effectively sort out usable shot, fine sand dust and crushed shot, ensuring the quality of cleaning and reducing the cost of consumables. This is one of the core components of the equipment's performance.
Wear-resistant parts materials (such as guard plates and blades) : When cleaning high-hardness castings, wear-resistant materials such as high-chromium alloys should be selected to extend their service life.
Electrical control system: Stable and reliable. It is best to have a parameter memory function to facilitate the switching between different products.
Shot selection (related to both equipment and castings) :
Cast steel shot/sand: The most commonly used, low cost, suitable for most ferrous metal castings. The particle size is selected based on the surface roughness requirements.
Stainless steel shot: It is used for non-ferrous metals, stainless steel castings or scenarios where no iron contamination is required.
Ceramic shot/glass beads: Used for extremely soft metals (aluminum, magnesium, copper), fine castings or in situations where a finishing effect is required.
Summary and suggestions
Multi-variety, small-batch, complex parts → hook-type shot blasting machine (universal type, strong adaptability).
For large quantities, medium and small-sized, and non-collision parts → belt-type shot blasting machine (economical and efficient).
Super-large batch, assembly line production → through-type or suspension chain shot blasting machines (the king of automation).
Precision, flat parts → Rotary table shot blasting machine (stable quality).
Non-ferrous metal castings → The type of equipment is not limited (commonly used hooks or turntables), but non-ferrous shot materials and precise force control must be provided.
The final and most crucial step: Take your typical casting samples (or detailed drawings, photos) to a reputable shot blasting machine manufacturer for a trial blasting test. Seeing the cleaning effect with your own eyes, asking about power consumption, the replacement cycle of vulnerable parts, etc., is the most reliable way to make the right choice.