al of clamping-finish, the controller orders the scale door of the weighing hopper to open, the material fills into the packaging bag from the weighing hopper, when the weight inside the weighing hopper is less than the setting zero value, the controller closes the scale door of the weighing hopper in 1 second delay. When the controller peels off the tare weight of the weighing hopper, the packing hopper executes the next metering cycle. The clamping-mechanism will loosen the bag after the scale