Gravimetric vs. Volumetric Feeders: Quick Comparison
| Feature | Gravimetric Feeder | Volumetric Feeder |
|---|---|---|
| Measurement Method | Weight | Volume or Feed Rate |
| Typical Accuracy | Within ±1% of target feed rate | Approximately 1.5%–5% |
| Automatic Adjustments | Yes | Not typically |
| Material Tracking | Yes | Limited |
| Best For | High-accuracy additive control | General additive dosing |
Quick Answer
The primary difference between gravimetric and volumetric additive feeders is how they measure material. Gravimetric feeders measure additives by weight and automatically adjust feed rates to maintain accuracy. Volumetric feeders meter additives based on volume or feed rate.
Our volumetric feeders provide accuracy ranging from approximately 1.5% to 5%, depending on feeder design and material consistency. Gravimetric feeders typically maintain accuracy within ±1% of the target feed rate because they continuously measure material by weight and automatically compensate for process variations.
Both technologies provide reliable additive feeding. The best solution depends on your application, material costs, and desired level of process control.
As a result, understanding these differences can help processors select the best solution for their production goals.
Accurate Additive Feeding Starts with the Right Technology
Accurate material feeding plays an important role in plastics processing. Whether you’re adding color concentrate, regrind, pellets, powders, or other additives, the right feeding system can help improve consistency, efficiency, and process control.
Two common technologies used throughout the plastics industry are gravimetric feeders and volumetric feeders. While both are designed to meter additives into a process, they operate differently and offer unique advantages depending on the application.
Understanding these differences can help processors select the best solution for their production goals.
What Is a Gravimetric Feeder?
A gravimetric feeder measures and dispenses material based on weight.
AEC’s AF1000 Series Gravimetric Additive Feeder is a highly accurate, single-component feeder designed for injection molding, extrusion, and blow molding applications.
Its innovative double-hopper design features an outer protective shell and an inner floating weigh hopper mounted on a single-point load cell. This design helps provide exceptional weighing precision.
The AF1000 continuously monitors material usage. In addition, advanced control algorithms automatically adjust feed rates as operating conditions change.
What Is a Volumetric Feeder?
A volumetric feeder meters material based on volume or feed rate rather than weight.
AEC’s AF Series Volumetric Additive Feeders and DD Series Digital Dosing Systems are designed for precision metering of color concentrate, regrind, pellets, micro pellets, powders, and other additives.
These feeders introduce additives into the process stream at a controlled and repeatable rate. As a result, processors can maintain consistent material delivery in injection molding, extrusion, and blow molding applications.
What Is the Biggest Difference Between Gravimetric and Volumetric Feeders?
The primary difference is how material is measured.
Gravimetric feeders measure materials by weight.
Volumetric feeders measure materials by volume or feed rate.
Furthermore, because gravimetric feeders continuously verify the amount of material being fed, they can automatically adjust output to maintain the desired feed rate.
Volumetric feeders deliver additives at a predetermined feed rate using augers or dosing discs, depending on the feeder design.
Both technologies provide reliable additive feeding, but they achieve this goal in different ways.
Which Type of Feeder Offers Greater Control?
Both feeder technologies provide consistent additive dosing. However, they offer different levels of process feedback and control.
The AF1000 Series Gravimetric Feeder is designed to provide highly accurate additive control through the use of precision load-cell technology and advanced control algorithms.
The system continuously monitors material delivery and automatically adjusts performance to maintain the desired feed rate. Therefore, processors can maintain tighter control over additive usage.
Volumetric feeders provide dependable and repeatable material dosing and remain a popular solution for many plastics processing applications.
Which Type of Feeder Is Better for Color Concentrates and Additives?
Processors use both gravimetric and volumetric feeders for color concentrates and additives.
For example, AEC’s AF Series and DD Series Volumetric Feeders precisely meter:
- Color concentrates
- Regrind
- Powders
- Pellets
- Micro pellets
- Other additives
Meanwhile, the AF1000 Gravimetric Feeder offers highly accurate additive control, real-time material monitoring, and automatic feed-rate adjustments.
Ultimately, the best choice depends on the application, material costs, and desired level of process control.
Can Gravimetric Feeders Help Reduce Material Costs?
Yes.
The AF1000 Series Gravimetric Feeder is designed to provide precise additive control. This helps processors confidently feed expensive colors and additives at the desired let-down ratio.
By continuously monitoring material consumption and automatically adjusting feed rates, the AF1000 helps improve production efficiency and can contribute to material cost savings.
In addition, the system can store up to 500 recipes. It also offers real-time data collection and material consumption management through Modbus TCP/IP communication capabilities.
Which Feeder Is Easier to Clean During Material Changes?
Material changes and cleanout procedures can impact productivity, especially during frequent color changes.
The AF1000 Series Gravimetric Feeder features patented Smart-Clean automatic quick-purging technology. This system can clear colorant in approximately 10 seconds, helping reduce manual clean-outs and downtime.
The AF Series Volumetric Additive Feeders are also designed for efficient material changeovers. Their interchangeable stainless-steel auger assembly simplifies cleaning.
AF-1 and AF-2 models include a swing-out sample and clean-out door for easy access during maintenance.
The DD Series Digital Dosing Systems simplify material changes through a quick-disconnect additive station that can be removed for off-machine cleaning and changeovers.
Together, these features help processors improve efficiency while reducing maintenance and cleanup time.
When Should You Choose a Volumetric Feeder?
Consider a volumetric feeder when:
- You feed color concentrates or additives
- You process pellets, micro pellets, powders, or regrind
- You want a dependable and economical feeding solution
- You need consistent and repeatable additive dosing
- You value simple operation and fast material changes
When Should You Choose a Gravimetric Feeder?
Consider a gravimetric feeder when:
- Additive feeding accuracy is especially important
- You process expensive colorants or additives
- You need material consumption tracking
- You want real-time process monitoring
- Your production goals include maximizing material efficiency and reducing waste
Which Feeder Is Right for Your Process?
The right feeding solution depends on your materials, production requirements, accuracy expectations, and process goals.
Volumetric feeders provide dependable additive dosing and remain a popular choice for color concentrates, regrind, pellets, powders, and other additives. Depending on feeder design and material consistency, they typically deliver feeding accuracy between 1.5% and 5%.
However, some applications demand greater control over additive usage. In those situations, gravimetric feeders continuously measure material by weight and automatically adjust output to maintain the desired feed rate. As a result, gravimetric systems such as the AEC AF1000 Series typically achieve feeding accuracy within ±1% of the target feed rate.
Therefore, processors working with expensive colorants, specialty additives, tight tolerances, or material tracking requirements often benefit from gravimetric technology. Meanwhile, many everyday additive applications continue to perform successfully with volumetric feeding systems.
Whether you prioritize simplicity, cost-effectiveness, or maximum additive accuracy, AEC offers both gravimetric and volumetric feeding solutions for injection molding, extrusion, and blow molding operations. By understanding the strengths of each technology, processors can confidently choose the solution that best supports their production objectives.
