Grain crop specific gravity separator (specific gravity table) is a key equipment that utilizes the differences in specific gravity, particle size, surface characteristics, etc. of materials to achieve material stratification and separation through the vibration of the inclined table or the action of airflow.Its inclination angle and size (length, width) are the core parameters that affect the selection effect, and are directly related to the material separation efficiency, purity and processing capacity. The following is a detailed analysis of the influence of inclination angle and size on the selection effect:
1、The influence of tilt angle on the effect of fine cleaning machine
The inclination angle of the specific gravity table (the angle between the table and the horizontal plane) is the core parameter that determines the material flow state and stratification effect. Its influence is mainly reflected in three aspects: material flow speed, stratification time and separation accuracy:
（1）Impact on material flow rate: The inclination angle directly determines the flow rate of the material on the table.
Too small inclination angle (such as < 5°): The gravity component of the material along the table is insufficient, the flow rate is too slow, and even local accumulation occurs. At this time, the material cannot pass through the table in time, which can easily lead to overlapping of stratification areas, incomplete separation of light impurities and target materials, and reduced processing capacity.
Too large inclination angle (such as > 20°, depending on the crop): The gravity component of the material is too large, the flow rate is too fast, and the residence time on the table is too short. Even if the material can be initially stratified, it will be discharged together because it is “too late to separate”, resulting in residual light impurities (such as shriveled grains, worm-eaten grains) or loss of target materials (such as plump grains being misjudged as impurities).
（2）Impact on material stratification: The core of gravity selection is “stratification”: heavy materials (full grains) have greater gravity and are easy to pass through the material layer to contact the table surface, and move downward with the vibration of the table surface or air flow; light materials (shrunken grains, impurities) float on the upper layer and move to the upper end of the table surface (or be blown away by the air flow). The tilt angle affects this process by changing the “stratification dynamics”.
Moderate inclination angle (such as 5°-15°, depending on the crop): the material flow speed matches the stratification speed, heavy materials have enough time to sink to the table surface, and light materials have enough time to float up and gather in a specific direction, eventually forming a clear “heavy material area”, “medium-heavy material area” and “light impurity area”, with the highest separation accuracy.
Differences in adaptation of different crops: Due to different specific gravity, shape, and surface friction coefficient, the optimal inclination angle of different crops varies.
（3）Impact on separation accuracy: Too small or too large an inclination angle will result in blurred stratification, and the “purity” and “clarity” of the final selected material will decrease.
2、The influence of size on the effect of the selection machine
The size of the density table (mainly length and width) indirectly affects the selection effect by affecting the “residence time”, “distribution uniformity” and “processing capacity” of the material:
（1）The influence of table length: The length determines the total residence time of the material on the table, which is the “time guarantee” for stratification and separation.
Too short length (e.g. < 1m): The material path from feed to discharge is short. Even if the inclination angle is reasonable, the stratification is not completely completed, resulting in incomplete separation and more “critical impurities” mixed in the target material.
Too long length (e.g. > 3m): Although it can extend the residence time, it may lead to:
Excessive accumulation of heavy materials at the end, squeezing the upper light materials, but destroying the stratification;
Increase in equipment size, increase in cost, and vibration or airflow is easy to attenuate over a long distance, resulting in inconsistent separation effects at the front and end.
（2）Influence of table width: The width mainly affects the processing capacity and material distribution uniformity
Too narrow width (e.g. < 0.5m): The amount of material that can be carried per unit time is small, the processing efficiency is low, and it cannot meet the needs of large-scale production; but the airflow/vibration distribution of the narrow table is more uniform, and the separation accuracy is relatively high.
Too wide width (e.g. > 1.5m): The processing capacity is increased, but the “edge effect” is prone to occur – the airflow intensity and vibration amplitude at the edge of the table are greatly different from those in the center area, resulting in uneven stratification of materials in the width direction and a decrease in the overall selection purity.
3、The synergy between tilt angle and size
The tilt angle and size do not affect the selection effect independently, the two need to match and cooperate.
The inclination angle and size of the gravity machine ultimately determine the selection effect by affecting the material flow rate, residence time, layer clarity and distribution uniformity. In actual application, parameters need to be optimized according to crop characteristics (specific gravity, particle size, surface characteristics) and selection goals (such as removing light impurities and separating fullness).
Post time: Jul-25-2025
