What Factors Affect the Accuracy of a Multihead Weigher?
You buy a multihead weigher to get exact weights at high speed. But sometimes the bags come out a few grams too heavy or too light. That small gap adds up fast. Extra product in every bag is money you give away, and short bags can cause trouble with local weight rules.
As a multihead weigher manufacturer with years of line experience, we see the same causes again and again, and a Kenwei multihead weigher is built to deal with them.
The great thing about accuracy issues is that they will typically be very obvious, and most can be easily resolved. Below are some key contributing factors based on real experience on packing lines.
1. How the Product Is Fed
This is the most common mistake. If you don’t feed each hopper evenly, the multihead weigher will not be able to find as many good combinations. If the feed is uneven, some hoppers will be overfilled and others underfilled. This reduces the number of good combinations available.
Issues with the feed could be a lumpy conveyor feed, an overfilled top cone, or an intermittent feeder. Having a consistent and smooth feed into your weigher will solve more accuracy issues than anything else.
2. The Product Itself
Not all products behave the same. Dry rice flows easily. Products such as pickles, noodles, cheese, or frozen dumplings won’t work. They are sticky, so they’ll stick to the pans and hopper. Or they’re delicate and will break. They can also be large and irregular, meaning the weight of the hopper contents will be very different.
If your product is sticky, flat, or an unusual shape, then a standard machine will struggle. The weigher needs to have the correct surface, hopper,r and feeding method for your product,t so a multihead weigher manufacturer will want to know what material you will be weighing before suggesting a particular model.
3. Load Cells and Electronics
The load cell is the part that actually reads the weight. If yours is bad, you'll get wrong numbers, and nothing will resolve it. Good load cells are sensitive, stable, and settle quickly.
Electronics matter too. Weight signals get noisy because of machine movement and electrical interference. Good filtering cleans that noise up. Over time, load cells will begin to drift. This is known as zero drift and can be caused by temperature fluctuations, continuous vibration, and excess loads on the cell.
On a Kenwei multihead weigher, we use high-precision load cells and a multi-sampling stable mode. The weigher takes multiple readings to make sure it has accurate results.
4. Hopper Size and Target Weight
Many buyers pick a weigher by speed alone. The hopper size is also a consideration. If you want to produce small weights but have large hoppers, then you will be measuring very small amounts of product from each hopper, giving reduced accuracy. If the hoppers are too small for a big target weight, you need many hoppers to fill each pack, and speed drops.
Every Kenwei multihead weigher, offers 0.5L, 1L, 1.6L, 2.5L and 5L hoppers on multihead weighers. For tiny, valuable doses, our 14 Head 0.3L High-accuracy Multihead Weigher (JW-AS14) handles 1 to 60g with an accuracy of X(0.5) at up to 120 packs a minute. For heavier loads, the Big 14 Head Noodle Weigher (JW-AM14) uses 5L hoppers and covers 100 to 3000g. Note: Actual speed may vary depending on the product and application.
5. Number of Heads and Combination Logic
A multihead weigher works by weighing a small amount in each head, then picking the group of heads whose total is closest to the target. More heads mean more possible groups, and more groups mean a closer match.
That said, more heads do not fix everything. The weight in each head should be spread in a smart way. Research on combination weighing shows that how you share product among the hoppers changes the final accuracy. This is part of the software setup, and it is one reason a good supplier tunes the machine for your product instead of shipping it with default settings.
6. Speed Versus Accuracy
Run the machine faster and accuracy often slips. Hoppers have less time to settle, and the load cell has less time to read. The speed rating on a brochure is also a best case. Real speed depends on product shape, density, and target weight.
The smart approach is to find the speed where accuracy is still on target, then run there. Pushing past it only creates giveaways and rejects.
7. Vibration, Air, and the Environment
The weigher sits on the floor of a busy factory. Shaking from nearby machines can pass through the frame and into the load cells. Air flow can be an issue. Small amounts of air can cause the hopper to rise slightly, which will affect the reading. Airflow covers and baffles can help prevent this.
Cold environments and moist clean downs can also affect the electronics. The Kenwei multihead weigher IP65 Waterproof Model (JW-A10 and JW-A14) is sealed with an automatic drain pipe and waterproof rubber sleeves on the vibrators. It can be cleaned with a high-pressure water gun and has a drying unit to ensure no moisture enters the parts responsible for weighing.
8. Settings and Calibration
Even a great machine needs good settings. Vibration amplitude for each linear pan, feed time, hopper timing, and settling delay all change the result. If one pan vibrates harder than the next, the hoppers fill unevenly.
Calibration also needs a regular check. Weights shift slowly over weeks and months, so a quick test with known weights keeps things honest.
Our weighers let you adjust the amplitude of each linear pan on its own, and they store up to 100 product programs. That means an operator can switch from one product to another by calling up a saved setting instead of starting from scratch. A no-product auto-pause function also keeps the weigher stable when the feed runs empty.
Alt text: Operator adjusting settings on a Kenwei weigher touch screen
9. Cleaning and Maintenance
A hidden cause of inaccurate weighing can be product leftover. Sticky product left on the hopper door or pan will alter the product flow and add extra unaccounted weight. Parts can become worn, screws loose, and dirty sensors can cause issues.
Our weighers are easy to clean. They are made from food-grade stainless steel and have a tool-free design, meaning product parts can be removed easily. The weighers are also modular, meaning parts are interchangeable,e keeping maintenance times down.
10. The Equipment Around the Weigher
The weigher is not the only equipment on the line. If the packing machine below is not feeding product at the right time, the weigher will have to wait, causing disruption. If the conveyor doesn't feed the weigher correctly, that brings us back to factor 1.
Kenwei specializes in manufacturing weighing equipment and works with professional packaging machine manufacturers to provide suitable equipment combinations for different production line requirements. For example, our JW-B11 Horizontal Weighing & Packing System is great for snack products. Our JW-B12 Double Inlet system has a weigher and pre-made pouch machine. We also make checkweighers and metal detectors to catch out-of-tolerance bags before they ship.
Quick Reference Table
| Factor | What Goes Wrong | Simple Fix |
|---|---|---|
| Product feed | Uneven filling of hoppers | Steady conveyor and feeder flow |
| Product type | Sticking, breaking, odd shapes | Right pans, hoppers and feeding method |
| Load cells | Noise and zero drift | Quality cells, filtering, regular zero check |
| Hopper size | Too big or too small for target weight | Match hopper volume to dose |
| Speed | Less settling time | Run at the best speed, not the top speed |
| Environment | Shaking, airflow, moisture | Solid base, wind cover, sealed case |
| Settings | Uneven pan amplitude | Adjust each pan, save product programs |
| Cleaning | Residue and worn parts | Tool-less parts, set cleaning schedule |
A Few Kenwei Models at a Glance
| Model | Best For | Weighing Range | Accuracy | Max Speed |
|---|---|---|---|---|
| JW-AS14 (0.3L) | Herbs, ginseng, small granules | 1 to 60g | X(0.5) | 120 packs/min |
| JW-A10 (IP65) | Frozen food | 10 to 1000g | X(0.5) | 65 packs/min |
| JW-A14 (Pickles) | Pickles, short strips, small blocks | 10 to 500g | X(1) | 45 packs/min |
| JW-A14 (Noodle) | Noodles, scallops, sticky items | 100 to 1500g | X(1) | 60 packs/min |
Note: Actual speed may vary depending on the product and application.
Choosing the Right Partner
Accuracy starts with the right match between machine and product. Guangdong Kenwei Intellectualized Machinery Co.,Ltd. has built weighers in Zhongshan, China, since 2006. Our factory produces more than 5,000 multihead weighers a year, and we ship to over 100 countries. All of our machines have CE approval,l and many have OIML and SGS certificates. A two-year warranty is provided for Kenwei multihead weighers, linear weighers, checkweighers, and metal detectors. Most queries about service can be answered within 24 hours.
If you are comparing a multihead weigher manufacturer for your line, tell them what you pack, your target weight, and your speed goal. A good supplier will use that to pick the hopper size, pan type, and settings for you. That is how we work at Kenwei, and our team can also build custom machines when a standard model will not fit.
►Visit Kenwei to see the full range of Kenwei multihead weighers, linear weighers, checkweighers, and packing systems, and send us your product details for a free quote.
