Variation in density of material will affect Blending, so a study of volume and weight blending is essential to understand the correct blending.
VOLUME BLENDING :
In all blending equipment, the cotton is charged into hopper. It is assumed that the height of cotton in the hopper will be kept constant, resulting in constant volume, the" density of the cotton is constant and rate of feed is constant for all fibre component and for the over all mass of cotton.. But these assumptions are far from true in the ^actual working condition further the spiked aprons are not designed to maintain constant weight feeding from a cotton source of varying density and volume
WEIGHT BLENDING :
In weighing hopper feeder or in latest mixing bale opener (M.B.O) at last, the tuft leave the machine at delivery duct from where they fall into weighing pans.
The charge of the weighing pan is set on a weighing beam between 50 g and 1350 gram in one gram steps.
The weighing pans are first filled at the fast speed. Before the charge reaches the set weight, an electronic switch switches the material transport motor to slow speed.
When the full charge has been reached, another electronic switch trips the material transport motor off immediately and shuts the closing flap so that no further tufts can fall into weighing’ pans.
When the weighing pans of all the weighing hopper feeder or MBO ('3 or 4) of a tuft blender have been filled, the bottom traps of all the weighing pans are opened pneumatically at the same time. The material falls on to the blending conveyor of the Tuft blender machine.
The filling of the weighting pans begins again immediately.
