Karra Model-2; Variation of 'm'

 

Karra S-Curve (d50 = 3.2 mm, m = 4)

ere is your Karra S-curve with the d₅₀ point clearly marked at:

Particle size = 3.2 mm
Passing probability = 0.50 (50%)

Variation of m

Short Summary

m	Effect
High	Sharp cut, clean oversize/undersize
Low	Poor cut, lots of middlings
Depends on	Design + Operating conditions

Typical Industrial Values

Screen Type	Typical m
High-frequency screens	5 – 10
Standard wet vibrating screens	4 – 7
Dry screens / coarse sizing	2 – 5
Worn, overloaded screens	1 – 3

Multi-curve Karra S-curve graph, showing how the sharpness index (m) affects screening performance:

• m = 2 → very poor separation

• m = 4 → normal vibrating screen

• m = 6 → wet/high-frequency screens

• m = 10 → excellent sharp cut

The steeper the curve, the better the separation quality.
Higher m = smarter screening. ✔️