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Volumetric VS. Gravimetric

Are you looking for the perfect dosing solution for your production process? Regarding dosing systems, manufacturers can choose two primary methods, volumetric and gravimetric, but which one is best for your production?

This blog post will explore the differences between volumetric and gravimetric dosing systems and how they impact manufacturing processes. We’ll look at the pros and cons of each method and consider the factors that influence the choice between the two.

Whether you’re a production manager looking to optimize your manufacturing process or a business owner considering a switch to a new dosing system, this blog post will provide valuable insights to help you make an informed decision.

Key Takeaways

  • Dosing units are designed to ‘precisely’ measure the number of additives used in your process and, when utilized appropriately, have been shown to reduce defective production.
  • The loss-in-weight technique is a multi-step procedure that enables precise and efficient material distribution.
  • The loss-in-weight unit continuously monitors the weight of the material in the hopper throughout the dosing operation.
  • Volumetric dosing methods work well in processes that produce smaller quantities with less emphasis on color accuracy.
  • Volumetric dispensing machines can offer satisfactory results with proper calibration.
  • Gravimetric dosing is critical for businesses that place a premium on color accuracy.
  • The demands and goals of each factory dictate the final decision between volumetric and gravimetric dosing.

What is the difference between volumetric and gravimetric dosing?

Volumetric systems dose material according to occupied space, or volume. On the other hand, gravimetric systems dose materials by weight. Gravimetric systems can measure material usage more precisely, whereas volumetric systems are less accurate.

Explanation of the importance of accurate measurements in various industries

Every company we work with experiences a time when they we’re looking for ways to reduce costs within their production process. Truthfully, there are many reasons why a company should precisely measure the usage of their additives in their production process. According to our data, companies that use a high-end dosing unit, whether volumetric or gravimetric, experience a significant drop in waste.

According to our clients, these benefits are what make our machines stand out. Now it’s up to you to consider a switch to accurate dosing equipment.

– Less waste

– Less downtime

– Fewer costs

– Simplified maintenance

– A safer work environment

– Measurability for quality control

What is Dosing?

A dosing device in the dosing and mixing unit draws an exact amount of material from a supply hopper or similar container. Then, it transfers it to a reservoir or directly into the throat of the processing machine. Because it is responsible for feeding the correct amount of ingredients to the neckpiece, the dosing device plays a crucial role in the outcome.

A dosing unit in your production draws a certain amount of material from the supply hopper into a reservoir or directly into the throat of the processing machine. Dosing units are made to ‘precisely’ measure the number of additives used in your process and are proven to reduce faulty production if used correctly.

So what does ‘using correctly’ mean? It means that there are specific challenges that come with gravimetric and volumetric dosing. Simply having a dosing unit in your process doesn’t mean you are using it right.

In some cases, producers use volumetric dosing units and unknowingly overdose on the amount of additives. Overdosing is a significant financial strain for producers, but it often goes unnoticed by management. In many cases, switching to a gravimetric system can save these companies money in the long run.

Supposedly, some factories want the best, so they use gravimetric technology. However, when volumetric dosing units are calibrated correctly, the dosing unit can dose the correct amount, without consideration for vibrations. There might be color discrepancies in a few products, but volumetrics can be the way to go for companies that place little value on color accuracy.

Explanation of the differences between volumetric and gravimetric measurements

What is Volumetric Measurement?

In volumetric dosing methods, ingredients are measured by volume (in cubic centimeters or meters). Although, volumetric units need calibration to correctly dose additives.

Calibration is always necessary when working with new materials or batches. Manufacturers usually set volumetric systems to dispense more than required to be safe because they cannot automatically account for parameter changes like bulk density.

Definition of volumetric measurement

Volumetric dosing is measuring the volume of the ingredients according to a metric, like weight or meters.

Advantages of Volumetric Dosing

  • Relatively low-priced dosing system
  • Accurate dosing cylinder (High-end dosing equipment)
  • Stepper motor speed starts from 0.1 up to 200 rpm. 

Disadvantages of Volumetric Dosing

  • Manual recalibration required
  • Limited control over your product quality
  • Limited monitoring and reporting options
  • It cannot automatically compensate for fluctuations in density
  • Sensitive to material build-up
  • No automatic detection of material supply interruption

The Biggest Disadvantage of Volumetric Dosing

What would happen if you decreased your additive usage by 0.5%? Manufacturers often dispense more additives than necessary to play it safe and limit the amount of faulty production. However, these manufacturers don’t know they can reduce their waste while using exact dosages by using gravimetric dosing technology.

If we consider an extrusion line that runs at 1000 kg (2200 lb) per hr, 24 hr a day, and 365 days a year, the annual production will be 8.76 million kg (19.31 million lb). At an additive cost of €6 per KG for the extrusion line, the yearly additive cost is €891.072. If you can make process improvements that reduce additive use by 17.65%, you will save €157.248 annually.

We understand that every factory tackles production differently. Therefore, these are just averages taken from our ROI tool, which you can use to calculate what you can save in your production process!

In short, incorrect dosing due to inaccurate calibration does not always affect the quality of the output. However, over time it will have a significant negative financial impact.

What is Gravimetric Measurement?

Gravimetric dosing systems measure input material using one or more integrated load cells. This means that weight and speed are the only parameters considered. Because the system continues to dose material until it reaches the required target weight, fluctuations in density do not affect the outcome. A further benefit is that you can confidently say how much total material – by weight – has been used; this is very important if you need to document the process for quality management purposes.

Definition of a Gravimetric Feeder

A gravimetric feeder, also known as a loss-in-weight feeder, is a self-calibrating dosing system based on the weight in speed. On the other hand, volumetric feeders dose based on volume in speed.

Loss-in-weight Technology

Loss-in-weight gravimetric dosing systems use a load cell to weigh the whole unit and, as the name suggests, record the product’s weight loss. With this technology, the central control system regulates the flow rate or the cylinder’s speed based on the load cells’ cues.

Powered by this technology, the load cells can emit signals to the cylinder, allowing you to regulate your throughput for higher accuracy automatically and significantly decrease faulty production.

Because the flow rate is continuously monitored and adjusted based on weight, variations in bulk density, grain size, and rheology do not affect the precision of the product quality when using loss-in-weight systems.

However, ensuring that the dosing devices are appropriately loaded with the material is vital, which is why high-quality systems have integrated, fully autonomous material restocking designs.

A Step-by-step Explanation for Loss in Weight Technology

Loss-in-weight technology is a step-by-step process that ensures accurate and efficient material dispensing. Let’s break it down into its essential components and explain how it works:

  1. Weighing System: The loss-in-weight system consists of a specially designed weighing system that accurately measures the weight of the dispensed material. This system typically includes load cells or weighing sensors for precise weight readings.
  2. Material Hopper: The dosing process begins with a material hopper or container that holds the bulk material to be dispensed. The hopper has an outlet or discharge mechanism through which the material flows.
  3. Initial Calibration: The system undergoes an initial calibration before initiating the dosing process. This calibration establishes the baseline weight of the empty hopper or container, referred to as the tare weight.
  4. Target Weight Setting: The operator sets the desired target weight for dispensing the material. This target weight determines the amount of material the system should deliver accurately.
  5. Start of Dosing: The dosing process begins by activating the system. The material starts flowing from the hopper through the outlet or discharge mechanism.
  6. Weight Monitoring: Throughout the dosing process, the loss-in-weight system continuously monitors the weight of the material in the hopper. The load cells or weighing sensors provide real-time weight measurements.
  7. Control System: A control system, typically a computerized or programmable logic controller (PLC), receives the weight readings from the weighing system. It compares the measured weight with the target weight set by the operator.
  8. Dosing Adjustment: If the measured weight deviates from the target weight, the control system adjusts the dosing rate accordingly. This adjustment ensures that the desired amount of material is dispensed accurately.
  9. Continuous Monitoring and Adjustment: The loss-in-weight system dynamically adjusts the dosing rate throughout the process. It compensates for variations in material flow, density, or other factors to dispense the desired weight accurately.
  10. End of Dosing: The dosing process continues until the loss-in-weight system reaches the target weight. At this point, the system stops the material flow, and the desired weight of the material has been dispensed accurately.

Fortunately, gravimetric technology can eliminate the influence of vibrations stemming from production processes. Moreover, most machines with this technology demonstrate exceptional versatility in handling various materials.

Additionally, it’s worth noting that our gravimetric technology goes beyond mere weight measurement. It can adapt and adjust the flow rate in response to external environmental factors. This dynamic adjustment ensures consistent and precise dosing even in the presence of factors such as fluctuations in ambient conditions or other external disturbances.

As a result, our gravimetric technology guarantees optimal performance and accurate dispensing, regardless of the surrounding conditions.

Advantages and Disadvantages of Gravimetric Dosing


  • Self-adjusting / self-calibrating
  • 100% control over your product quality
  • Easy to operate
  • Ability to process regrind material
  • Monitoring and reporting options
  • Higher savings on expensive additives
  • Fluctuations in density do not affect the outcome.
  • In-sensitive to material build-up
  • Automatic detection of material supply interruption
  • Accurate dosing cylinder
  • Stepper motor speed starts from 0.1 up to 200 pm.


  • Relatively more expensive than a volumetric feeder but has a short ROI
  • Depending on the design and material flow (rheology) – e.g., free-flowing, sticky, or fluid material – the impaired flow of ingredients can decrease product quality.

The final output of your dosing mechanism and device depends on various environmental factors. External factors’ impact can vary based on vibration, material change procedures, material dimensions, throughput rate, or valve frequency. Important to note that there are more factors influencing the process since a dosing unit is only one part of your production process.

What is rheology?

Rheology is the study and understanding of how materials flow and deform in response to applied forces in the context of dosage. It is a branch of science concerned with the behavior of fluids, pastes, and other things under stress or strain.

Rheology is important in dosing applications because it influences dispensing items’ flow characteristics and uniformity.

Comparison of Volumetric and Gravimetric Measurement

Differences between the two methods

Weight or Volume?

Volumetric dosage is based on the amount of substance, whereas gravimetric dose is based on weight. Systems for volumetric dosing calculate the quantity depending on the volume of the substance, such as the number of cubic centimeters or meters it occupies.

On the other hand, gravimetric dosing techniques calculate the dosage by meticulously weighing the components in grams or kilograms. As a result, gravimetric dosing provides constant and dependable dose additives and is exceptionally accurate.

For example, a gravimetric dosing device is ideal for organizations that require exact formulas and doses. This is so that manufacturers can control and customization more effectively due to the weight of the components.


Devices for volumetric dosage need to be calibrated after a material switch.

Therefore, your manufacturing operations will experience more manual labor and downtime as a result of the calibration process’ need for trial and error.

On the other hand, the automatic calibration capabilities of gravimetric dosing systems enable them to excel at handling a variety of materials flawlessly. In addition, this automated calibrating capability reduces downtime in your manufacturing process and eliminates the need for manual labor.

By readily responding to different materials, gravimetric dosing systems provide adequate and uninterrupted dosing, boosting productivity and streamlining manufacturing processes.


Volumetric and gravimetric techniques both have significant advantages depending on the production facility’s needs.

Volumetric dosing systems perform effectively in facilities that produce smaller amounts with less attention to color accuracy. In addition, these systems are inexpensive, making them a popular choice. With adequate calibration, volumetric dispensing machines can produce satisfactory results.

On the other hand, gravimetric dosing gives firms more control over their manufacturing processes by providing precise data on additive usage. As a result, the gravimetric dosage is essential for companies that value color accuracy highly. In addition, gravimetric dosage aids in resource optimization and long-term cost reduction by significantly reducing waste, and material consumption.

While gravimetric metering units may be more expensive initially, the potential savings on additives make them a worthwhile investment for organizations concerned about color accuracy.

The needs and goals of each factory ultimately determine the choice between volumetric and gravimetric dosing. Volumetric administration is ideal for smaller-scale production when color accuracy is not critical. Despite its higher starting cost, gravimetric titration provides better control and precision, making it perfect for firms that value additive precision and color uniformity.