The angle of nip in crushing rolls primarily depends on particle friction and geometry. Which factor below does it not significantly depend upon?

Introduction / Context:
The angle of nip is the maximum angle between the roll faces at which a particle can be drawn into the rolls. It is a function of friction and the relative size of the particle to the roll radius.

Given Data / Assumptions:

• Classical nip analysis assumes quasi-static conditions.
• Friction and size geometry control nipping.

Concept / Approach:
The condition for nipping can be written in terms of coefficient of friction and the ratio of particle size to roll diameter. While speed affects capacity and power draw, the static nip angle relation is independent of rotational speed in first approximation.

Step-by-Step Solution:
Relate nip angle to friction coefficient and size ratio.Recognize roll diameter and feed size appear geometrically.Exclude speed as a primary variable for nip angle.

Verification / Alternative check:
Design charts show nip angle versus size ratio and friction, with no speed term in the basic nipping criterion.

Why Other Options Are Wrong:
Diameter/feed size/friction: explicitly present in nip equations.Product size correlates with nipping and breakage once drawn in.

Common Pitfalls:
Assuming higher speed increases nip angle; it can increase throughput but not the geometric limit.

Final Answer:
Speed of the rolls