Vibrating Screen G-Force Calculator

Linear vs Circular vs Elliptical Motion

• Linear Motion: Created by counter-rotating eccentric weights. Material moves in a straight line at an angle to the screen surface. Best for scalping and heavy-duty applications.
• Circular Motion: Single shaft with eccentric weights creates circular throw. Material tumbles and stratifies well. Common in inclined screens.
• Elliptical Motion: Combination of linear and circular - adjustable by weight timing. Provides excellent material control and is popular in shale shakers.

Stroke Length and Frequency Relationship

• G-force increases with the square of frequency but only linearly with stroke
• Doubling RPM quadruples G-force; doubling stroke only doubles G-force
• Higher frequency with shorter stroke = fine screening (less panel wear)
• Lower frequency with longer stroke = coarse screening (better conveyance)

G-Force Requirements for Different Materials

• 2-3 G: Light, dry materials - vibratory feeders
• 3-5 G: Aggregate screening, scalping operations
• 4-6 G: Sand classification, dewatering screens
• 5-7 G: Fine screening, drilling fluid solids control
• 6-8 G: High-capacity shale shakers, difficult materials
• 8+ G: Specialized applications, high-frequency screens

Screen Efficiency and Material Flow

• Material must lift off the screen surface to allow passage of fines
• Optimal bed depth is 2-4x the aperture size
• Too much G-force causes "bouncing" and reduced efficiency
• Material velocity depends on stroke, frequency, and screen angle
• Typical material velocities: 0.3-0.5 m/s for screening, up to 1 m/s for feeders

Counter-Rotating Eccentric Weights Concept

• Two weights rotate in opposite directions on parallel shafts
• Synchronized by timing gears to maintain phase relationship
• Horizontal force components cancel out (sum to zero)
• Vertical force components add together (double the force)
• Result is pure linear motion perpendicular to shaft axis
• Angle of vibration set by screen deck angle (typically 5-25 degrees)