A multihead weigher measures several small portions of product, then combines selected portions into one dose for packaging. It is also called a combination weigher. Instead of bringing every hopper up to the full pack weight, the controller chooses a group of available weights whose total meets its programmed selection rules.
For a pouch packaging project, this explains both the benefit and the limitation. The machine has several portions to choose from, but the result still depends on how your product feeds, weighs and discharges. The weigher also needs to work with the equipment that receives the dose.
How combination weighing works
Consider a simplified example with five available portions: 31, 34, 36, 39 and 42 grams. For a 100 gram target, the controller could select 31, 34 and 36 grams, giving a total of 101 grams. Other portions remain available for a later selection, subject to the machine’s operating sequence.
These invented numbers illustrate the calculation only. They are not a performance test or a suggested production setting. A real system uses its configured limits and available hopper weights; an exact match is not always possible.
The practical advantage is choice. Several modest portions can provide a closer total than a single large portion. However, a controller cannot select a useful combination if the feed system has left too few suitable portions available.
Follow the product through the machine
A common circular design receives bulk product above a central distribution area. Feed channels spread the product towards separate holding hoppers. These supply weigh hoppers, where load cells measure individual portions.
Once the controller selects a combination, the relevant weigh hoppers open. Their contents travel through a collection chute towards the package. Some installations use an intermediate timing hopper to coordinate release with the packing machine.
Meanwhile, emptied weigh hoppers receive more product for the next cycle. Hoppers that were not selected may retain their portions. The exact refill and release sequence depends on the design.
Ask your supplier to show the complete product path on the proposed layout. This makes it easier to identify equipment that sits outside the weigher quotation, such as bulk feeding, a support platform and the pouch machine.
What products suit a multihead weigher
Typical applications include nuts, confectionery, snacks and other products that can be divided into separate portions. Product behaviour matters more than the category name. Two snack products can need different handling because one flows freely while the other breaks easily or sticks to contact surfaces.
Use the following comparison to prepare your sample review.
| Product behaviour | What to examine | Evidence to request |
|---|---|---|
| Free flowing pieces | Distribution between feed channels | A continuous run with representative product |
| Fragile pieces | Impacts through hoppers and discharge | Product condition before and after packing |
| Sticky or moist pieces | Release from contact surfaces | A trial of the proposed feeding arrangement |
| Bulky or irregular pieces | Usable hopper space and package opening | Tests at the required portion size |
Specialised designs exist for fragile products, including lower drops and gentler transfer paths. Sticky products may require a different feeding method, such as screw feeding. These are configuration choices, not features that every multihead weigher includes.
For your trial, send normal production material rather than only the easiest batch. Describe changes in moisture, coating, piece size or temperature that occur during a shift. Ask the supplier which variations the proposed machine needs to demonstrate.
Why the number of heads is only part of the decision
Available portions
Head count describes how many weighing positions a machine has. Additional available portions can increase the choices used in combination weighing. Yet head count alone does not establish accuracy or the output of your packaging line.
Hopper and dose fit
A useful comparison also considers hopper capacity, feeding behaviour, discharge time and the target dose. A bulky portion needs enough space even when its weight is low. A small dose needs suitable portions to combine, rather than simply the largest available hoppers.
Compare like for like
Compare proposals using the same product and pack specification. Ask each supplier to identify the tested configuration and provide results for your smallest and largest intended doses. This gives you a more useful basis for selection than comparing headline speed or head count in isolation.
How the weigher connects to pouch packaging
The weigher prepares the dose. A separate machine forms a pouch from film or presents a premade pouch, then handles filling and sealing. The two processes must agree on when product can be released.
During an equipment review, trace one dose from the weigh hoppers into the actual pouch. Check the opening, transfer route and available filling time. A successful discharge into a wide collection container does not demonstrate that the same dose will enter a narrow pouch cleanly.
Ask the integration team to explain what happens when the pouch machine pauses. The control sequence should define when to hold product and when another release is permitted. Include the upstream supply in that discussion so that a downstream stop does not leave responsibilities unclear.
For acceptance, record completed, acceptable pouches over an agreed test period. A weigher cycle count is useful process information, but it is not the same measurement as finished saleable packs.
What accuracy and giveaway figures should tell you
Put tolerance in context
A quoted weighing tolerance needs context. Request the target dose, product, run duration and individual results behind it. Also establish where the measurements were taken: at the weigher discharge or in the finished package.
Compare giveaway fairly
Product giveaway is the extra product supplied above the intended pack quantity. A combination weigher can help control it, but no general savings percentage describes every application. Compare actual results at the same target, acceptance rules and production conditions.
An average close to the target can hide a wide spread between individual packs. Therefore, review the sample results as well as the average. Your quality team should define the applicable acceptance criteria; a supplier’s demonstration setting should not silently become your production specification.
Plan a trial that answers your purchase questions
Prepare a short brief with the product description, representative samples, target weights, pouch dimensions and required output. Add any constraints on product damage, cleaning and available installation space.
During the trial, collect evidence for the questions that affect the purchase:
- Does product reach the weighing positions consistently during a sustained run?
- Do the recorded doses meet the agreed weight criteria?
- Does the complete dose enter the pouch without visible loss or obstruction?
- Does the finished product retain the condition you require?
- What work is needed to change product, clean the equipment and restart?
Keep the run settings and sample sequence with the results. If a supplier changes the configuration during the demonstration, record the change so that the quotation and acceptance plan refer to the same arrangement.
For cleaning, ask to see access to product-contact parts and the approved method for the proposed equipment. Removable hoppers alone do not establish that an entire machine can be washed down. Have your production and quality teams review the demonstrated procedure.
Questions buyers often ask
Discuss your weighing and pouch requirements
A multihead weigher should be evaluated with the product and package it will actually handle. Use the operating principle to ask focused questions, then base your decision on a documented trial. Send Huapack your product details, target weights, pouch samples and required output. Ask for a proposal that identifies the weighing configuration, packaging interfaces and evidence needed to assess the complete system.
