How Does a Multihead Weigher Work?
- PacMatix
- 1 day ago
- 6 min read
Introduction
If you've started researching automated packaging equipment, you've probably come across the term multihead weigher. Although it appears to be a relatively simple machine, a modern multihead weigher uses advanced combination weighing algorithms to achieve extremely accurate pack weights at high production speeds.
A multihead weigher is one of the most important machines in modern automated packaging lines. It accurately weighs products by calculating the best combination of individual weigh hoppers before discharging them into a Vertical Form Fill Seal (VFFS) machine, horizontal flow wrapper, tray sealer or other packaging equipment.
Understanding how a multihead weigher works will help you: understand the purpose of each machine section compare different machine designs evaluate weighing performance understand how it integrates with other packaging machinery make a more informed purchasing decision.
What Is a Multihead Weigher?
A multihead weigher is an automated weighing system designed to accurately portion products before they enter a packaging machine.
Unlike a conventional scale that weighs one portion at a time, a multihead weigher simultaneously weighs product in multiple weigh hoppers before calculating the combination that most closely matches the target weight.
This combination weighing principle allows exceptional weighing accuracy while maintaining very high production speeds.
Multihead weighers are commonly used for:
snacks
confectionery
frozen vegetables
frozen seafood
coffee
biscuits
pet food
fresh produce
nuts
pasta
hardware
pharmaceutical products
many other free-flowing products.
The Basic Multihead Weighing Process
Although the entire weighing cycle happens in fractions of a second, it consists of six carefully coordinated stages.
1. Product Infeed
The product enters the machine via an infeed conveyor, bucket elevator or vibratory feeder.
It is delivered onto the top of the machine where the weighing process begins.
A consistent product supply is essential for maintaining weighing accuracy and production speed.
2. Product Distribution
The product first lands on a central distribution cone.
Depending on the machine design and application, this cone may rotate or vibrate to evenly spread product around the machine.
The product is then transferred onto radial feeders positioned around the outside of the cone.
The purpose of the distribution system is to ensure every weighing station receives a consistent supply of product.
Even distribution is critical because poor product flow can reduce weighing accuracy and overall machine performance.
3. Radial Feeders
The radial feeders transport product from the centre of the machine towards each individual weighing station.
Each feeder is independently controlled, allowing the machine to regulate product flow according to:
product size
product shape
target weight
production speed
product characteristics.
Different products require different vibration settings to achieve the best weighing performance.
4. Feed Hoppers
The product is transferred from the radial feeders into the feed hoppers, where it is temporarily held before being discharged into the weigh hoppers below.
The feed hoppers ensure a continuous supply of product is always available for each weighing cycle, allowing the machine to maintain high production speeds without interruption.
By controlling the flow of product into the weigh hoppers, the machine can optimise weighing accuracy and respond quickly to changes in product characteristics or production speed.
5. Weigh Hoppers
Product is released from the feed hoppers into the weigh hoppers located directly beneath them.
Each weigh hopper is mounted on an individual high-precision load cell that continuously measures the exact weight of the product inside.
A typical multihead weigher may contain:
10 weigh hoppers
12 weigh hoppers
14 weigh hoppers
16 weigh hoppers
20 or more weigh hoppers
depending on the application.
6. Combination Calculation
This is where the intelligence of the machine comes into play.
Rather than simply emptying one hopper, the control system instantly analyses the weight of every available weigh hopper.
It then calculates thousands of possible combinations in milliseconds before selecting the combination that most closely matches the target weight while minimising product giveaway.
This process is known as combination weighing.
It is the reason multihead weighers can achieve exceptional accuracy while operating at production speeds exceeding hundreds of weighs per minute.
7. Product Discharge
Once the ideal combination has been selected, the chosen weigh hoppers open simultaneously.
The weighed product falls into a central discharge chute before entering the packaging machine below.
Depending on the production line, this may be:
a Vertical Form Fill Seal (VFFS) machine
a horizontal flow wrapper
a tray sealer
a thermoforming machine
another automated packaging system.
As soon as the product has been discharged, the empty weigh hoppers begin refilling while the next weighing calculation is already underway.
This continuous cycle allows modern multihead weighers to maintain extremely high production speeds.
How the Entire Process Works Together
Although the weighing cycle appears simple, numerous machine functions occur simultaneously.
These include:
product feeding
product distribution
radial feeder control
load cell measurements
combination calculations
hopper timing
discharge synchronisation
communication with the packaging machine.
Modern servo-controlled multihead weighers coordinate every movement electronically to maximise weighing accuracy, reduce product giveaway and increase production efficiency.
Main Components of a Multihead Weigher
Component | Function |
Infeed system | Supplies product to the machine |
Distribution cone | Evenly spreads product around the machine |
Radial feeders | Transport product to each weighing station |
Feed hoppers | Temporarily hold product before weighing |
Weigh hoppers | Precisely weigh individual portions |
Load cells | Measure product weight |
Control system | Calculates the optimum weight combination |
Discharge chute | Transfers weighed product to the packaging machine |
Touchscreen HMI | Controls recipes and machine settings |
Servo and vibration controls | Optimise product movement |
Advantages of Multihead Weighers
Compared with manual weighing or simple volumetric filling systems, multihead weighers offer:
exceptional weighing accuracy
reduced product giveaway
consistent pack weights
high production speeds
gentle product handling
fast product changeovers
integration with automated packaging systems
reduced labour requirements.
What Determines Multihead Weigher Performance?
Not all multihead weighers perform equally.
Performance depends on factors such as:
number of weighing heads
load cell accuracy
software algorithms
product distribution design
vibration control
hopper design
machine rigidity
ease of cleaning
operator interface
available local support and spare parts.
These differences often explain why two machines with similar advertised production speeds can deliver very different real-world performance.
Frequently Asked Questions
What is a multihead weigher?
A multihead weigher is an automated combination weighing system that uses multiple weigh hoppers to accurately portion products before packaging.
What products can be weighed on a multihead weigher?
Multihead weighers are commonly used for:
snacks
confectionery
frozen foods
fresh produce
coffee
pet food
nuts
biscuits
pasta
hardware
pharmaceutical products
many other free-flowing products.
3.What is the difference between a multihead weigher and a linear weigher?
A multihead weigher simultaneously weighs multiple portions before selecting the best weight combination.
A linear weigher dispenses product from several linear channels and is generally better suited to lower production speeds or products that are difficult to distribute evenly in a circular weighing system.
Can a multihead weigher work with different packaging machines?
Yes.
Multihead weighers commonly integrate with Vertical Form Fill Seal (VFFS) machines, horizontal flow wrappers, tray sealers, thermoforming machines and complete automated packaging lines.
Conclusion
A multihead weigher is one of the most important components in a modern automated packaging line. By combining high-speed product handling with sophisticated combination weighing technology, it delivers exceptional weighing accuracy while minimising product giveaway and maximising production efficiency.
Whether you're installing a new packaging line or upgrading an existing system, understanding how a multihead weigher works is the first step towards selecting the right weighing technology for your application.
Related Articles
How Does a Vertical Form Fill Seal (VFFS) Machine Work?
Multihead weighers are most commonly installed above Vertical Form Fill Seal (VFFS) machines, automatically delivering accurately weighed product into each bag. If you'd like to understand what happens after the product leaves the weigher, read our How Does a Vertical Form Fill Seal (VFFS) Machine Work? guide, which explains the complete packaging process from film unwind to finished pack.
How Does a Flow Wrapper Work?
Not all products are packaged in bags. Many food products such as biscuits, bakery items, snack bars and fresh produce are wrapped individually using horizontal flow wrappers. Our How Does a Flow Wrapper Work? guide explains the complete wrapping process, from product infeed through to the finished sealed pack, and highlights the key differences between flow wrapping and vertical bagging systems.
About the Author
Ettienne van Vuuren
Founder & Technical and Sales Director, PacMatix Pty Ltd
Founder and Technical & Sales Director of PacMatix Pty Ltd, Ettienne has more than 25 years of practical experience in industrial packaging machinery, specialising in horizontal flow wrappers, Vertical Form Fill Seal (VFFS) machines, multihead weighers and complete automated packaging systems.
Throughout his career, he has commissioned, serviced and optimised packaging equipment across Australia, Papua New Guinea and Southern Africa, helping food manufacturers improve packaging performance, reliability and production efficiency.