1. Definition and Principle
Sand Blasting
Sand blasting uses compressed air to propel abrasive particles (such as quartz sand, aluminum oxide, or glass beads) at high speed onto the surface of a workpiece. Through mechanical friction, it removes rust, oxide scale, old paint, or surface contaminants, thereby cleaning and roughening the surface for subsequent processes like painting, plating, or welding.
The main purpose is cleaning and increasing surface roughness.
Shot Peening
Shot peening uses metal shots (such as steel or stainless-steel balls) that strike the surface of a workpiece at high velocity, producing localized plastic deformation and a compressive residual-stress layer. This process enhances fatigue strength, stress-corrosion resistance, and wear resistance.
The main purpose is strengthening the surface structure.
⚙️ 2. Main Differences
| Item | Sand Blasting | Shot Peening |
|---|---|---|
| Purpose | Cleaning, oxide removal, surface preparation | Strengthening, improving fatigue life |
| Media | Quartz sand, alumina, glass beads | Steel shot, stainless steel shot, ceramic shot |
| Mechanism | Grinding / cutting action | Impact / plastic deformation |
| Surface Appearance | Rough, matte | Smooth, uniform, compressive stress layer |
| Typical Applications | Pre-painting, plating, or welding cleaning | Springs, gears, shafts, turbine blades |
| Result Feature | Improves coating adhesion | Improves fatigue and crack resistance |
| Surface Hardness Change | Little or none | Increases surface hardness |
| Risk of Workpiece Deformation | Low | Possible if stress is excessive |
🔧 3. Typical Applications
Sand Blasting:
Removing oxide scale or rust from stainless-steel pipes or flanges
Pre-coating or pre-painting treatment
Cleaning castings or weld seams
Shot Peening:
Springs, gears, crankshafts, and aircraft engine blades
Fatigue strengthening or stress-relief treatment
🧠 Summary in One Sentence
Sand blasting cleans the surface; shot peening strengthens the surface.
