4. Efficiency assessment of abrasive blasting

An efficiency assessment of all blasting methods with abrasives can be made through the generated kinetic energy E_K and its output at the impact on the surface.

In order to accelerate the body and to keep it going at a possibly high speed work has to be performed. This one then exists in the form of kinetic energy in the body.

If

E_k = kinetic energy of the body (Nm or Joule)

m = mass of the body (kg)

v = velocity of the body (m/s)

then applies

This shows that

   the change of the mass has linear and

   the change of the velocity quadratic effects.

The kinetic energy of the abrasive increases linearly at the same speed at increasing mass.

The kinetic energy of the abrasive increases squarely at the same mass at increasing velocity.

Influence of the grain size of the abrasive on the blasting result

By reducing the medium grain size the number of grains increases exponentially.

“Maximum coverage is achieved with fine abrasive grain.”
“Maximum roughness height is achieved with rough abrasive grain.”

Coverage is a measure for the impacts per mm².

The abrasive weight thrown off (M) per unit time

The medium grain weight (m)

Result:
If the diameter of the grain doubles

then    the weight of the grain will increase by eight times    the kinetic energy will increase by eight times    the coverage will reduce to one eighth.