A linear weigher portions product by feeding it along a controlled path and measuring the dose by weight. A common arrangement uses a vibrating tray to supply a weigh hopper. Once the weighing cycle is complete, the hopper releases the portion towards the package.
For your pouch project, understanding that sequence helps you ask the right questions. The weigher must control the dose, transfer it cleanly and work with the receiving pouch machine. This guide focuses on linear vibratory net weighers for dry products, rather than every machine sold under the broader term weigh filler.
Follow the product from feeding to discharge
The supply hopper holds product above the feeding system. A vibrating tray moves material towards the weigh hopper, where a weighing sensor measures the accumulating load. The controller uses that measurement to control feeding.
Many configurations use a faster feed stage followed by a slower finishing stage near the target. The first stage supplies most of the dose. The finer flow gives the controller a more gradual approach to the required weight. The exact sequence and settings depend on the equipment and product.
After weighing, the hopper opens to release the portion. It then closes for the next cycle. In an integrated line, the discharge must also match the receiving machine’s readiness. Ask the supplier to demonstrate the complete sequence, including the signals between the two machines.
The word linear describes the general feeding arrangement. It does not establish how many weighing channels are fitted or how their discharges are coordinated. A drawing of the product path is more useful than a head count alone.
Understand what net weighing means
In the net weighing arrangement discussed here, product is weighed in a separate hopper before it enters the final package. The package itself is not the weighing vessel during that step.
Other filling systems weigh material as it enters a container supported on a scale. That different arrangement requires attention to the empty container’s weight. Ask where weighing actually happens in the proposed system so that the quotation and trial use the same definition.
A weight recorded in the weigh hopper also does not prove that the same amount reached the pouch. Product could remain in the transfer path or be lost during discharge. Check the finished pack as well as the machine’s displayed result.
Which products deserve a linear weighing trial
Linear vibratory weighers are used for suitable dry products such as seeds, nuts and small granules. The feeder and hopper must suit the actual material. A product that flows freely in one condition may behave differently after a change in grade or handling.
Describe the product before asking for a machine recommendation. Include piece size, visible fines, stickiness and how it arrives at the filler. Supply representative samples, including variants that are difficult to handle.
| Product characteristic | Question for the demonstration | What to record |
|---|---|---|
| Large or uneven pieces | Can the final part of the dose be controlled | Individual fill weights and cycle times |
| Fragile product | Does feeding and discharge damage the pieces | Product condition before and after filling |
| Sticky residue or poor flow | Does material remain in the tray or hopper | Residue and interruptions during a run |
| Several ingredients | Does each pouch have the required composition | Ingredient checks as well as total weight |
These questions help define a useful trial. They do not imply that every linear weigher can handle each condition. For mixed products, an acceptable total weight alone does not demonstrate the required ingredient ratio.
Read speed and accuracy claims together
A linear weigher needs time to feed, complete the weighing step and discharge. A faster feed setting may change the behaviour near the target. Ask for accuracy results at the proposed production rate, rather than accepting separate demonstrations of maximum speed and best accuracy.
Clarify the meaning of each figure in the quotation. Is the stated tolerance in grams or as a percentage? Does it describe individual portions, an average or a particular test condition? Which product and fill size were used?
For illustration, one percent of 100 grams is 1 gram, while one percent of 1,000 grams is 10 grams. Those are mathematical examples, not an accuracy claim for any machine. A percentage without its target weight does not tell you the size of the allowed difference in grams.
Ask for a sequence of individual results, the number of samples and any adjustments made during the test. Record the average, but do not let it replace the individual values. Also agree how the reference weighing equipment and empty pouch weight will be checked.
Connect weighing performance to pouch output
The full pouch line may wait for filling, pouch handling or sealing at different times. A weigher’s discharge count is therefore not automatically the number of acceptable sealed pouches produced.
Review the discharge chute, the pouch opening and the available filling time as one interface. Check whether the portion enters cleanly and clears the seal area. Ask what the controls do when the receiving pouch is absent or the packaging machine pauses.
Use these three checks when reviewing the line proposal:
Signals
Define the handoff signals between the weigher and the pouch machine.
Responsibility
Identify who supplies and tests the chute, mounting and package interface.
Acceptable output
Measure acceptable finished packs over an agreed period under the proposed conditions.
If the proposal uses several weighing channels, ask how each contributes to one finished pack. Multiple channels may operate in different ways. Do not assume that every additional channel directly multiplies output.
Compare alternatives by how they create a dose
Linear net weighing
A linear net weigher commonly builds a portion by feeding product into a weigh hopper towards a target.
Combination weighing
A multihead combination weigher selects a combination of separately weighed portions. Both use weight measurements, but the dosing sequence differs.
Volumetric dosing
A volumetric cup filler, in contrast, measures product using a cavity of a set volume. That distinction matters when evaluating weight control, although each option still needs a product trial and a suitable package interface.
Avoid choosing from a universal ranking of speed, cost or accuracy. Ask each supplier to test the same product, target weights and pouches. Compare the resulting fill records, acceptable output, cleaning access and changeover work. This keeps the decision tied to your process.
Questions buyers often ask
Prepare a weighing brief for your pouch project
Send Huapack your product samples, target fill weights, acceptable variation and pouch details. Add your required finished-pack output, available installation space and cleaning or changeover needs. Request a proposed dosing arrangement and a trial plan covering the complete route from feeding to the filled pouch. A useful proposal makes clear what has been demonstrated and what still needs testing.
