Page 46 - HUB-4 Magazine Issue 97

Aggregate Washing & Screening
2. Manufacturing and Assembly Process Deficiency –
Structural adjustments post-installation are common and
can change the center of gravity or increase the machine's
weight, which reduces efficiency.
3. Operational Deficiency – Increasing volumes that exceed
the recommended limits or the miscalibration of vibrators
that put an undue strain on units are common operational
deficiencies.
4. Inadequate Maintenance – Neglecting to monitor pads and
springs on screening structures, not following lubrication
procedures, and not addressing rust promptly are common
and costly failure mechanisms.
5. Wear and Deterioration – These factors are unavoidable,
but proper installation and maintenance of quality
equipment can extend the system’s lifespan.
Vibratory Amplitude and Frequency
Amplitude refers to the magnitude or intensity of the
vibration, indicating how far an object moves from its resting
position. On the other hand, frequency indicates how many
cycles of vibration occur per unit of time (measured in Hertz).
Higher frequency can increase volume but has the potential to
increase screen wear and stress on the frame if force outputs
are not considered.
Vibrator Motion and Placement
The placement and angle of the vibrators influence how the
motion occurs. With the correct slope and amplitude
calculated, gravity will assist the material down the screen.
Linear side-to-side motion is effective for sectors such as
mining and recycling, as it allows material to spread across the
screen. Mounting vibrators on the sides of the rack causes
larger materials to shift and roll to each side.
Linear up-and-down motion is highly effective for sand
biofiltration and particulate dewatering. With vibrators
mounted on rails above the material flow, the internal weights
lift and drop a specialized screen made of durable fine mesh.
[Fig.4]
Figure 5 – Proper way to adjust vibratory eccentric weights.
Electric and Hydraulic Screen Vibrators
The weight and volume of the bulk handling environment
require a powerful vibrator to do the job effectively. While
electric screen vibrators are common, hydraulic vibrators are
more applicable for portable screen applications where no
electricity is available. [Fig.5]
Figure 5 – Proper way to adjust vibratory eccentric weights.
Industrial electric vibrators for material screening should use
inverter-duty rated and Class H insulated windings to prevent
overheating in continuous-duty environments. Martin®
Engineering’s Screen Vibrators produce up to 16,500 lbs (7,483
kg) of centrifugal force. The adjustable eccentric weights tailor
performance for 3- or 4-panel screens, featuring low-
maintenance, greaseable, long-lasting cylindrical roller
bearings.
An example of a hydraulic screen vibrator is the Martin®
Hydraulic Screen Vibrator, which provides up to 8,300 lbs
(3,855 kg) of centrifugal force for efficient material separation.
The IP66 enclosure ensures a dry and grit-free internal
environment and uses the same mounting bolt patterns as
electric vibrators.
Conclusion
A well-constructed system, along with proper calibration and
placement of vibrators for the application, is essential for
efficient and optimized screen separation. To further extend
the equipment’s life, these systems should be easy to maintain
and accessible, ensuring both workplace safety and lower
operational costs.
Research
[1] B. Ramatsetse, K. Mpofu, O. Makinde, et al; Design
And Structure Optimization Of A Reconfigurable
Vibrating Screen For The Mining And Mineral Processing
Industries. Tshwane University of Technology. New
technology and innovation in the Minerals Industry
Colloquium, Southern African Institute of Mining and
Metallurgy, Emperors Palace, June 2016.
[2] T. Linhares , A da Silva Scari , C. Vimieiro; Causes Of
Failures In Vibrating Screens: A Literature Review.
Minerals Engineering, Volume 218, November 2024
Figure 4 – Hydraulic vibrators set on a sand dewatering screening system
delivering linear motion.
Elliptical rotational motion is prominent in agriculture for the
threshing process, but also in recycling and bulk processing.
Set in front of or behind the screen, the action causes a
“cheese grater” effect.
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www.hub-4.com March/April - Issue 97