Solutions
1. Die-Casting Stage (Root Cause Resolution)
Measure    Specific Action
Eliminate surface cold shuts    Reduce slow shot speed to 0.15–0.25 m/s; adjust the fast-shot switchover point to prevent premature splashing of molten aluminum.
Increase surface density    Initiate pressure buildup earlier (advance the intensification start point); raise specific pressure to 80–100 MPa to ensure surface compaction.
Control subsurface porosity    Enhance degassing during melting (rotary degassing ≥15 min) to lower hydrogen content in the melt.
Optimize coating process    Apply a thin layer of release agent and blow dry; strictly prohibit pooling; reduce spray volume specifically opposite the ingate.
Increase mold temperature    Preheat the mold to 180–220°C to prevent premature crusting upon contact with cold mold walls.
2. Shot Blasting Stage (Symptom Management & Adjustment)
Measure    Specific Parameters
Switch to softer media    Use φ0.3–0.6 mm aluminum or stainless steel shot; strictly avoid large-particle cast steel shot.
Reduce blasting intensity    Lower impeller speed; keep blasting velocity within 40–50 m/s.
Adjust spray angle    Tilt the workpiece 30–45° to avoid perpendicular impact of shot media on the surface.
Control duration    Stop once the surface is clean to avoid over-blasting; consider two light passes instead of one heavy pass.
Pre-treatment    Degrease before shot blasting to prevent oil residue from affecting the uniformity of shot rebound.
3. Rapid Troubleshooting Guide
Peeling in flakes with curled edges → Cold shut or coating layer issue; check die-casting process.
Peeling with a pitted/pockmarked appearance → Subsurface porosity; check melting/degassing process.
Uniform powder shedding/crumbly surface → Insufficient density; check specific pressure and intensification timing.
Peeling only at edges or protrusions → Blasting parameters too aggressive; switch to softer media or reduce intensity.