A multihead weigher, also called a combination weigher, creates a target dose by weighing several small product portions independently and selecting a permitted combination close to the target. Product distribution, hopper population, discharge timing and the downstream packer all affect the real result.
A multihead weigher is an automatic dosing machine that forms a target weight from several smaller weighed portions. Product is distributed to multiple weighing positions, each position measures its portion, and the controller selects a permitted combination that approaches the target. The selected hoppers discharge into a bag, pouch, container or downstream packing machine.
In normal packaging use, the terms are often used for the same weighing principle. “Multihead” describes the multiple weighing positions, while “combination” describes the calculation that combines selected hopper weights. A supplier should still define the actual machine configuration because the name alone does not state the number of heads, hopper arrangement, feed system or discharge design.
Each head provides an independently measured product portion that can be considered by the controller. A feed hopper normally holds product ready for transfer, and a weigh hopper measures the next portion on a load cell. The useful combination is created from several available hopper weights, not from one bulk measurement.
A multihead weigher creates the dose before or during filling; a checkweigher verifies the finished pack afterwards. A line may use both. The multihead weigher controls the portions released to the packer, while the checkweigher provides downstream confirmation and may trigger rejection or process feedback according to the line design.
The physical product path creates the portions; the controller then chooses between those portions. Stable performance needs both parts of the process to work together.
Upstream equipment supplies product to the centre of the weigher at a controlled rate. The supply should replenish the machine without flooding or starving it.
The dispersion cone and radial feed trays move product towards separate feed hoppers. Product flow, vibration and contact-surface condition affect the size and repeatability of those portions.
Each available weigh hopper measures its contents independently. Empty hoppers are refilled from the corresponding feed hoppers according to the machine sequence.
The controller evaluates permitted combinations of available hopper weights and selects one that approaches the configured target under the machine rules.
The selected portions enter a collection chute or timing hopper and then pass to the bagger, pouch machine, jar or other receiving equipment.
The controller compares the weights currently available and chooses a permitted group whose total is closest to the configured target within the operating rules. The calculation is only as useful as the portions presented to it. If the feed system creates too few usable portions, software cannot fully compensate for the physical limitation.
The emptied hoppers are prepared for refilling while the remaining measured portions may stay available for a later cycle, depending on the machine design. The discharged dose moves through the collection route and the next release waits for the downstream-ready condition defined for the line.
The multihead weigher normally sits between controlled bulk feeding and the machine or station that receives the finished dose. That may be a VFFS bagger, a timing hopper, a pre-made pouch machine or a container-filling point. Height, access, discharge path and control interfaces should be planned as one system.
Not normally. It weighs product portions before they enter the pack and calculates the dose to release. The final pack weight also includes tare variation and any product lost or retained between the weigher and pack. A downstream checkweigher or agreed sample method may be used to verify finished packs.
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