The best effect of shot peening strengthening treatment of automobile gears is affected by the interaction of different conditions. The main process parameters are shown in the table below.
| Projection | Content |
| Condition | Velocity, Time, Density,Amount, Angle, Method, Temperature |
| Projectile | Material, Proportion, Hardness,Distribution of particle |
| Object | Heat-treated structure, Mechanical properties of materials, Gear modulus |