Gravity Table - Every Tool Has a Job

The Cimbria Heid Gravity Separator’s main job is density separation. A Gravity Table combines two elements, vibration and air, to cause a separation in density of the seed on the deck of the table.

This article is the third in a series I will be doing called Every Tool Has A Job. This idea came about because of the amount of customers I find myself going through the basics on why each machine is in a plant and what its specific purpose is. These articles will be short and to the point aiming to get you the basic level of knowledge on each piece of equipment in a cleaning facility.

Every tool has a job to do in a cleaning facility: Air Screen: width separation; Indent: length separation; Gravity Table: density separation; Optical Sorter: visual separation. In this article we will be discussing the Gravity Table.

The Cimbria Heid Gravity Separator’s main job is density separation. A Gravity Table combines two elements, vibration and air, to cause a separation in density of the seed on the deck of the table. A gravity table consists of a mesh deck which we are forcing air through via fans underneath the table combined with the table shaking back and forth. When both of these functions take place what happens is the air blowing up from the bottom causes the grain to behave like a fluid. When this happens the heavier seed migrates to the bottom layer and the lighter layer migrates to the top layer. This allows us to tilt the deck in such a way that we can “pour” the lighter fraction off to a corner. With the heavier seed being on the bottom and in contact with the mesh deck, the shaking back and forth causes the seed to “walk” uphill and separates into the good fraction on the high side of the table.

By combining these functions of vibration and air pressure we can effectively separate good seed from foreign material which removes impurities as well as increases germination and vigor of the seed lot.