Amplitude in vibratory screening is the maximum displacement (throw) of the screen surface from its rest position during each vibration cycle, typically measured in millimeters or inches. It is a critical operating parameter that directly affects screening efficiency, throughput, and material conveyance across the screen surface.
Amplitude works together with frequency (vibration speed in RPM) and lead angle to define the complete motion pattern of a vibratory separator. In round vibratory separators, amplitude is controlled by the position and mass of the counterweights on the motor shaft. Increasing amplitude increases the force acting on material on the screen, which increases conveyance speed and helps stratify the material bed — but too much amplitude can bounce material over the screen surface without adequate screening time.
Amplitude Effects on Screening Performance
| Amplitude Setting | Effect | Best For |
|---|---|---|
| Low (1–2 mm) | Gentle handling, longer residence time, slower conveyance | Fine powders, fragile materials, high-efficiency screening |
| Medium (2–4 mm) | Balanced conveyance and screening time | General-purpose screening, most applications |
| High (4–8 mm) | Aggressive throw, fast conveyance, strong de-blinding action | Coarse materials, wet/sticky products, high-volume scalping |
Why This Matters in Vibratory Screening
- Screening efficiency vs. throughput — Higher amplitude moves material faster (more throughput) but gives less time on the screen (lower efficiency). Finding the optimal balance is key to maximizing production.
- De-blinding action — Higher amplitude provides more aggressive screen surface motion, helping to prevent blinding on difficult materials.
- Material conveyance — Amplitude determines how quickly oversize material is conveyed to the discharge spout.
- Screen life — Excessive amplitude accelerates screen fatigue and shortens screen cloth life.
Related Glossary Terms
- Frequency (Screening) — Vibration speed, the complementary parameter to amplitude
- Lead Angle — Determines the direction of material travel
- Counterweights — The mechanism used to adjust amplitude
- Motion Generator / Vibratory Motor — Generates the vibration
- Screening Efficiency — Directly affected by amplitude settings
Amplitude FAQs
What is amplitude in vibratory screening?
The maximum distance the screen surface moves from its rest position during each vibration cycle. Controlled by counterweights on the motor.
How do I adjust amplitude?
On round separators, change the angular offset between top and bottom counterweights. Wider angle = more horizontal throw; narrower angle = more vertical throw. Adding or removing weight plates changes overall intensity.
Need Help Optimizing Your Screener?
ScreenerKing's technical team can help you dial in the right amplitude, frequency, and lead angle settings for your application. Contact us for process optimization support.