Aluminum Die-Cast Part Surface Treatment: Shot Blasting Process (Shot Peening Process）
Shot blasting is a critical surface treatment technique for aluminum die-cast parts, efficiently removing oxide scales, burrs, and other impurities while significantly enhancing surface finish, coating adhesion, and fatigue strength.
The process propels abrasive media—such as stainless steel shot or cut wire shot—at velocities of 50–75 m/s via a high-speed rotating wheel, using impact energy to clean and strengthen the surface. Compared to traditional sandblasting or manual grinding, shot blasting offers higher efficiency, superior consistency, and full compatibility with automated production lines, making it the industry standard in die-casting manufacturing.
Core Functions of Shot Blasting
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1. Surface Cleaning
Effectively removes oxide scales, sand adhesion, burrs, and oil residues, providing a clean substrate for subsequent coating, painting, or electroplating.
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2. Surface Strengthening (Primary Advantage)
The impact of shot induces plastic deformation in the surface layer, generating a compressive residual stress field that can increase fatigue strength by several times and significantly improves resistance to stress corrosion cracking.
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3. Enhanced Adhesion
Post-blasting surface roughness typically reaches Ra 1.6–6.3 μm, increasing surface area and eliminating contaminants—resulting in over 40% improvement in coating adhesion.
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4. Improved Aesthetic Quality
Spherical shot creates a uniform dimpled texture that produces a subtle “starlight” visual effect under light, enhancing perceived quality.
Recommended Shot Blasting Parameters for Aluminum Die-Cast Parts
Due to the low hardness of aluminum alloys, precise parameter control is essential to prevent surface damage:
| Parameter |
Recommended Range & Notes |
| Shot Material |
Use 304 stainless steel shot or cut wire shot; avoid hard cast steel shot to prevent excessive indentation |
| Shot Size |
0.2–0.6 mm; finer shot for precision parts, coarser for heavy descaling |
| Shot Velocity |
50–70 m/s; higher speeds risk surface damage—optimize via empirical testing |
| Processing Time |
5–15 minutes, adjusted based on part geometry, size, and initial condition |
| Impact Angle |
30°–75°, balancing coverage and impact efficiency |
| Wheel Speed |
1500–2200 rpm, suitable for soft materials to avoid over-peening |
| Conveyor Speed |
0.5–3 m/min (for through-type systems), ensuring thorough treatment without compromising throughput |
Critical Safety Note: Aluminum dust generated during blasting is flammable and explosive. Equipment must be equipped with an efficient dust collection system, and separator air velocity should be maintained at 2–3 m/s to prevent fine shot particles from being sucked away.
Common Issues and Optimization Strategies
- 1. Surface Lifting/Peeling: May result from excessive silicon/iron content in ADC12 alloy, porosity due to poor mold design, or improper blasting parameters. Solution: Optimize alloy composition, refine die-casting process, and conduct parameter trials.
- 2. Surface Discoloration: If aluminum shot is used, apply coating immediately in high-humidity environments to prevent oxidation-induced discoloration.
- 3. Smart Manufacturing Trend: Modern shot blasting systems integrate PLC controls for precise adjustment of angle, velocity, and media flow, enabling adaptive processing for complex geometries and driving the industry toward greater precision and energy efficiency.
- More information and a free quote of Aluminum die casting parts and the die casting working process, please feel free to contact: cnkylt@aliyun.com
