What process quality points should be focused on for shot blasting in Dalian?

Surface Preparation

Thoroughly remove oil, grease, and thick rust (mechanical or chemical pre‑treatment).

Eliminate salt residues and moisture to prevent post‑blasting corrosion, especially in Dalian’s marine atmosphere.

Process Parameter Control

Blasting intensity: 0.2–0.3 mmA for shipbuilding steel (e.g., Q355); 0.3–0.5 mmA for spring strengthening.

Achieve 100% coverage; adjust nozzle angles (45°–60°) and positions to eliminate blind spots.

Shot speed: 60–80 m/s; standoff distance: 150–250 mm.

Avoid over‑blasting by controlling exposure time (e.g., 3–5 min for 10 mm steel plate).

Abrasive Media Management

Select shot material and size: cast steel (∅1.2–1.5 mm, HRC 40–50) for heavy steel structures; glass/stainless steel beads (∅0.5–1 mm) for precision parts.

Regularly screen out deformed/worn shots (e.g., length/diameter >1.5); replenish at least 10% new media weekly.

Keep shot hoppers clean to avoid contaminating workpieces.

Equipment Maintenance & Calibration

Inspect nozzles weekly – replace if orifice wear exceeds 10% to maintain uniform shot distribution.

Perform dynamic balancing of impellers monthly to prevent vibration‑induced speed fluctuations.

Ensure dust collector efficiency ≥95% to avoid particle re‑deposition and meet environmental standards.

Calibrate blasting intensity quarterly using Almen test strips.

Quality Inspection & Traceability

Surface roughness: Ra 50–80 μm (ship plates) / Ra 10–30 μm (auto parts).

Coating adhesion: cross‑cut test (GB/T 9286), grade ≥1.

Salt spray test (GB/T 10125): ≥480 h no red rust for marine‑grade components.

Maintain records of parameters, media batches, and inspection results for full traceability.

Environmental & Safety Compliance

Dust emission ≤10 mg/m³ using bag filters + activated carbon systems.

Noise ≤85 dB(A) with soundproof enclosures.

Operators must wear dust masks, goggles, and protective clothing against shot ricochet and dust.