Inline vs. Rotary Filling Systems

Explore the key differences between these two essential packaging systems.

Both inline and rotary filling systems are vital to modern bottling and packaging operations, serving a wide range of industries with impressive efficiency. Choosing between them can be a challenge, as they share many core functions. Both are designed to fill containers accurately and reliably, can be configured for various product types, and are built to handle high-volume production demands. They are both composed of complex mechanical and electronic components, including conveyors, filling heads, and control systems. With so much overlap, it’s easy to wonder how different they can genuinely be.

Despite their functional similarities, you might be surprised to learn these systems are not always interchangeable. There are critical distinctions that make one a better fit than the other for specific operational needs. We will explain more about each of these filling systems below and have prepared a table that directly compares inline and rotary systems to help you evaluate which is right for your application.

What is an Inline Filling System?

Inline filling systems move containers along a single straight conveyor belt, filling them sequentially or in groups, with products like cosmetics, sauces, chemicals, beverages, cleaners, shampoos, or oils. This linear method offers benefits on the production floor, including flexibility, cost savings, and simplicity. It’s suitable for small to medium production runs and is a common sight in food, personal care, pharmaceutical, household goods, and chemical plants. Just a few of the items they pack are tubs, jars, and bottles.

Although there are many different inline system types, these generally fall into two categories: volumetric fillers and liquid-level fillers. Volumetric types are the most frequently chosen, popular in manufacturing for consistency and control. These are the machines that will use pistons, peristaltic pumps, gear pumps, augers, and/or flow meters. They are precise, but a bit slower than their rotary counterparts.

Liquid-level filling types use a cosmetic fill target (gravity, overflow, or vacuum), making them visually uniform and neat. They’re used for retail glass bottles and in sectors such as beverage production and window cleaner packaging.

There’s also another one worth mentioning — net weight. Used to fill expensive goods, this system uses weight-based controls and components such as load cells to improve accuracy and reduce waste. Many vendors offer custom configurations for these versatile machines for various container sizes, among other inline fillers.

What is a Rotary Filling System?

A rotary filling system is a machine with a circular carousel featuring multiple filling stations. It’s naturally fast and efficient, but built to run even faster through continuous-motion mechanics. It’s used to package mass-market items such as carbonated beverages, water, dairy, pharmaceuticals, and household chemicals. One of the best things about it is that it can be configured with specific nozzle technologies to handle high-speed demands efficiently, such as pressure filling, gravity filling, vacuum filling, and piston filling. Rotary system types fall into four different categories depending on the filling method used:

• Gravity (aka “atmospheric”): for free-flowing liquids
• Pressure: for carbonated drinks
• Vacuum: for delicate containers
• Piston: for viscous pastes

Inline vs. Rotary Filling Systems: Key Comparisons

This is the crucial part where we place these two systems side by side, compare their attributes, and find the best fit.

What Are the Types of Inline Filling Systems?

There are many different types of inline filling systems, each with unique features and applications. Several broad categories are listed below:

• Gravity inline fillers: These systems are the most straightforward and use gravity to fill containers. Gravity fillers are ideal for free-flowing, low-viscosity liquids like water, juice, and certain oils. They are widely used in the beverage and food industries for products that do not foam and require a consistent fill level.
• Piston inline fillers: Piston fillers use a volumetric cylinder to dispense a precise amount of product with each cycle. These machines are incredibly accurate and versatile, making them ideal for handling a wide range of product viscosities, from thin liquids to thick pastes like creams, gels, and sauces. They are popular in the cosmetic, pharmaceutical, and food industries.
• Pump inline fillers: This type of filling system uses various pump technologies (such as gear, lobe, or peristaltic pumps) to move product into containers. Pump fillers are particularly well-suited for specific product characteristics, such as filling chunky products without damage or handling sanitary applications. They offer great flexibility and accuracy, making them a strong choice for the food, chemical, and personal care industries.

What Are the Types of Rotary Filling Systems?

Rotary filling systems are classified by the method used to fill the product. Below are the primary categories of rotary fillers:

• Gravity rotary fillers: Use the force of gravity to fill free-flowing, non-carbonated liquids like water and juice.
• Pressure rotary fillers: Apply positive pressure to fill carbonated beverages and foamy products quickly.
• Vacuum rotary fillers: Create a vacuum in the container to draw liquid in, ideal for high-viscosity liquids or fragile containers.

Advantages of Inline Filling Systems Compared to Rotary Systems

Listed below are the advantages of inline filling systems compared to rotary systems:

• Inline systems have a lower initial investment and take up less floor space.
• Inline systems are simpler to set up, operate, and maintain, with faster changeovers.
• Inline systems can be easily scaled by adding more filling heads as production grows.
• Inline systems offer greater flexibility to handle various container shapes and sizes.

Disadvantages of Inline Filling Systems Compared to Rotary Systems

Listed below are the disadvantages of inline filling systems compared to rotary systems:

• Inline systems have slower production speeds than rotary systems.
• Inline systems are less efficient for high-volume, continuous operations.
• Inline systems can be less accurate with intermittent stop-start motions.
• The start-stop motion may cause more product spillage or inconsistent fills.
• Inline systems are not as well-suited for highly automated, 24/7 production lines.

Inline vs. Rotary Filling Systems: Detailed Comparison Table

Table 3 highlights the comparisons between inline and rotary filling systems:

Alternatives to Inline and Rotary Filling Systems

Below are some mutual alternatives to both inline and rotary filling systems:

• Net Weight Fillers: Like both inline and rotary systems, these machines fill containers. However, net weight fillers measure product by weight rather than volume, providing extreme accuracy. They are ideal for high-value products where minimizing giveaway is critical.
• Aseptic Fillers: Aseptic fillers sterilize both the product and packaging separately before filling in a sterile environment. They can handle sensitive products like dairy and pharmaceuticals, extending shelf life without preservatives.

Similarities Between Inline and Rotary Filling Systems

Inline and rotary filling systems are both composed primarily of automated components for packaging liquids. They also use various filling technologies, such as gravity, piston, pump, and overflow. Both types can also be configured in a wide variety of ways, each with its own unique set of properties and characteristics. Both inline and rotary systems are essential to modern manufacturing. They can be integrated with other packaging equipment to create a complete, efficient production line.

Other Comparisons for Inline Filling Systems

Listed below are some other systems that, depending on the application, may serve as stand-ins for inline filling systems:

Manual Filling Systems: This method is performed entirely by hand, typically using simple jugs, ladles, or gravity-fed spouts. It is generally used for home-based businesses or tiny hobby batches.

Semi-Automatic Filling Systems: Also called benchtop fillers, operator-assisted fillers, or tabletop machines, this is a variation of inline filling that requires an operator to place bottles and trigger the fill cycle. The process is done to bridge the gap between manual labor and full automation.

Net Weight Fillers: This system is based on weight rather than volume. It is a precise mass of the product measured by load cells (scales under the bottle), which provides a “guaranteed” weight ,critical when selling expensive products by mass.

Peristaltic Pump Fillers: This pump system uses rollers on a flexible tube to move the liquid. Peristaltic fillers combine high precision with zero risk of cross-contamination.

Time-Gravity Fillers: A system of timed valves with a supply tank above the filling heads. Typical configurations are cost-effective and straightforward. It is reliable and easy to maintain, finding use in chemical applications.

Overflow Fillers: The mechanism fills every bottle to the same visual level.

Other Comparisons for Rotary Filling Systems

Listed below are a few other alternatives to standard rotary filling systems:

Aseptic Fillers: An aseptic filler is created by maintaining a commercially sterile environment for the product and package. It is highly contamination-resistant and used in applications such as dairy, juices, and pharmaceuticals.

Volumetric Fillers: A system of pistons or measuring cups used in the filling of precise liquid volumes.

Pressure Fillers: This technology applies back-pressure to the bottle and is regularly used in the beverage industry for its ability to handle carbonated drinks without foaming.

Monoblock Systems: Monoblock systems can be combined with other functions to give them superior efficiency. Monoblock variants include the rinse-fill-cap block and the blow-fill-cap block. They are used in the production of bottled water, soft drinks, edible oils, and personal care products.

Electronic Fillers: A system of magnetic flow meters and valves, this machine is used in the food industry for its high hygiene and contactless filling.

Vacuum Fillers: A vacuum method is commonly used to handle viscous liquids and other thick products in narrow-neck bottles.

How FLSM Can Help

We hope this article helped explain the differences between inline and rotary filling systems, and that you’ve decided which one is best for your manufacturing needs. If neither sounds appealing, fret not! Net weight fillers or semi-automatic systems can replace them both. FLSM offers many different solutions using these technologies, including custom engineering, line integration, maintenance services, and much more! You can easily get your free quote here, or for more information on any of these machines or our services, please feel free to reach out to one of our reps.