Understanding Compaction

Compaction Basics

Unlike static rollers that depend on the weight of the machine to generate the forces required to compact materials, Sakai vibratory and oscillating rollers introduce dynamic forces that helps to generate a high compaction effect with far less effort and cost.

These dynamic forces are created by rotating one, or several off-balanced weights connected to shafts within a steel compacting drum. During vibration the rotation of one shaft with weight delivers a centrifugal force that is sufficient to lift and drop the heavy steel drum as it moves through its cycle. The height at which the drum lifts is referred to as amplitude. During oscillation the rotation of more than one shaft with weight creates the back and forth smearing affect as it moves through its cycle. Each cycle repeats itself as the machine moves across and compacts the material depth and surface.

Vibratory dynamic force typically increase the compacting force up to six times the actual static weight of the drum assembly. Like shaking up a box of corn flakes, this vibration rapidly moves the material particles, reduces the air voids between them, increases the material contact points. Vibratory and oscillating rollers help to rearrange the material particles at the same time for a denser fit.

It is imperative that machine speed, frequency and amplitude variations controlled by machine settings correlate to proper impacts per foot for consistency and mat smoothness. Compaction is a very technical process. For more detailed information, contact your Sakai representative today.

Basic Compaction Terminology

Frequency is simply the number of times per minute that the eccentric shaft rotates within the drum. 4000 VPM means the shaft rotates 4000 times per minute or 67 times per second. Sakai offers a full line of high frequency/4,000 VPM rollers with oil-bath-lubricated vibration shaft bearings throughout.

Centrifugal Force is the force generated in pounds by the eccentric weights rotating within the drum.

Nominal Amplitude is the vertical movement of the drum in inches created by the centrifugal force.

Operating Weight is the maximum weight of all machine components and operator.

Density refers to the amount of material occupying a given space.

VPM is vibrations per minute.

IPF is impacts per foot.