Flow Wrapper Glossary

Technical Reference | Flow Wrapper Terms and Definitions

Whether you are researching your first flow wrapper, comparing different machine manufacturers, or learning to operate a flow wrapping machine, you will quickly encounter a wide range of technical terminology. Some terms describe machine types, others refer to individual machine components, packaging materials or sealing technologies.

This glossary defines many of the most common terms used throughout the flow wrapping industry. It is intended as a practical reference for food manufacturers, packaging engineers, production managers, machine operators and anyone looking to better understand horizontal flow wrappers and the technology behind them.

The glossary is continually expanded as additional terminology and definitions are added.

A

Anvil

An anvil is the stationary or opposing component that works together with the cutting knife during the cross-sealing and cutting process of a flow wrapper. As the sealing jaws close, the knife cuts against the anvil to separate individual packs while maintaining a clean, accurate cut. The material, hardness and condition of the anvil play an important role in cut quality, knife life and overall packaging performance.

B

Box Motion Flow Wrapper

A Box Motion Flow Wrapper is a type of horizontal flow wrapper that uses a moving sealing jaw assembly which travels together with the product during the sealing cycle. By matching the speed of the product while the seals are being formed, box motion technology provides a significantly longer sealing dwell time than conventional rotary jaw systems.

Box motion flow wrappers are commonly used for modified atmosphere packaging (MAP), paper-based packaging materials, recyclable films, thicker laminates and products that require high-quality hermetic seals.

C

Cross Seal

A cross seal is the seal created across the width of the packaging film at each end of the product. The cross seal closes the package, separates one pack from the next and forms the distinctive end seals commonly seen on flow wrapped products.

Cross seals are typically produced by heated rotary sealing jaws or box motion sealing systems and are critical to both package integrity and product protection.

D

Dwell Time

Dwell time is the amount of time that the sealing jaws remain in contact with the packaging film while heat and pressure are applied to create a seal.

Longer dwell times generally allow stronger and more reliable seals, particularly when using thicker packaging films, paper-based materials or modified atmosphere packaging (MAP). Dwell time is influenced by several factors including jaw diameter, machine speed, sealing jaw design and whether the machine uses conventional rotary jaws or box motion technology.

E

Entry-Level Flow Wrapper

An Entry-Level Flow Wrapper is a general term commonly used to describe the first or lowest-priced machine within a manufacturer's product range. Because manufacturers define and position their product ranges differently, the term does not describe a specific engineering standard and may refer to machines designed around fundamentally different engineering philosophies.

The term is also frequently used throughout the packaging industry to describe lower-cost flow wrappers positioned primarily around purchase price. As a result, buyers should consider the engineering platform, machine capability, intended production environment and long-term operating requirements rather than relying solely on the description "entry-level."

F

Film Unwind System

The film unwind system is the section of a flow wrapper that holds, supports and feeds the packaging film into the machine. It maintains consistent film tension throughout the packaging process to ensure accurate film tracking, reliable print registration and consistent package quality.

Modern flow wrappers often use servo-controlled film unwind systems with automatic tension control to improve packaging consistency and reduce film waste.

Fin Seal

A fin seal is the longitudinal seal created as the packaging film is wrapped around the product and joined together. The overlapping film forms a raised fin along the length of the package, which is then sealed using heated sealing wheels.

The fin seal provides the primary longitudinal closure of the package and works together with the cross seals to completely enclose the product.

Fin Seal Wheels

Fin seal wheels, also known as longitudinal sealing wheels, are heated rotating wheels that create the longitudinal seal on a flow wrapped package. As the product passes through the machine, the overlapping film travels between the sealing wheels where controlled heat and pressure produce a continuous seal.

The design, diameter, surface finish and temperature control of the fin seal wheels all influence seal quality, machine speed and the range of packaging materials that can be processed successfully.

Flow Wrapper

A flow wrapper, also known as a flow wrapping machine, flow wrap machine or horizontal flow wrapper, is a packaging machine that wraps individual or grouped products in a continuous roll of flexible packaging film. The machine forms the film around the product using a forming box, creates a longitudinal seal, then produces cross seals before cutting the film to produce individual finished packs.

Flow wrappers are widely used throughout the food manufacturing industry to package bakery products, confectionery, snack foods, protein bars, fresh produce, frozen foods, medical devices and many other consumer products. Depending on the application, flow wrappers may package products using conventional plastic films, recyclable packaging materials, paper-based films or modified atmosphere packaging (MAP).

Although the terms flow wrapper, flow wrapping machine and flow wrap machine are often used interchangeably, they all refer to the same type of horizontal packaging equipment. To explore the different types of industrial flow wrappers available for food manufacturing applications, visit our Flow Wrappers page.

Forming Box

A forming box is the machine component that folds flat packaging film around the product before it enters the longitudinal sealing section of a flow wrapper. As the product passes through the forming box, the film is progressively shaped into a tube, allowing the overlapping edges of the film to be sealed together by the fin seal wheels.

The design and adjustment of the forming box have a significant influence on package appearance, film tracking, sealing consistency and the range of product sizes that can be packaged efficiently.

H

High-Speed Flow Wrapper

A High-Speed Flow Wrapper is one category of industrial flow wrapper designed for maximum production throughput in demanding manufacturing environments. These machines typically provide the highest operating speeds, the greatest degree of automation and the most advanced product handling capabilities within a manufacturer's product range.

High-speed flow wrappers are most commonly integrated into fully or partially automated packaging lines, where they operate in conjunction with automatic feeding, product distribution, inspection, cartoning and other downstream packaging equipment. Although they can be operated as standalone machines, they are generally selected for high-volume production environments where complete line automation is required.

Horizontal Flow Wrapper

A Horizontal Flow Wrapper is a packaging machine that transports products horizontally through the machine while wrapping them in a continuous roll of flexible packaging film. The film is formed around the product, sealed longitudinally and cross sealed before individual packs are cut apart.

Horizontal flow wrappers are widely used throughout the food industry because they can package a broad range of products at high production speeds while maintaining consistent package quality. The terms horizontal flow wrapper, flow wrapper, flow wrapping machine and flow wrap machine are often used interchangeably.

HMI (Human Machine Interface)

An HMI (Human Machine Interface) is the touchscreen operator interface used to monitor, control and configure a flow wrapper. The HMI allows operators to adjust machine settings, select stored recipes, monitor production, diagnose faults and view machine status in real time.

Modern HMIs improve ease of operation by providing intuitive controls, production statistics and maintenance information through a graphical interface.

I

Industrial Entry-Level Flow Wrapper

An Industrial Entry-Level Flow Wrapper is one category of entry-level flow wrapper representing the first machine within a professionally engineered industrial product range. Although these machines generally offer lower production capacity than medium-range or high-performance models, they are designed to achieve industrial engineering standards at the lowest practical purchase price by reducing production capacity and automation rather than engineering quality.

Infeed Conveyor

The infeed conveyor is the section of a flow wrapper that transports products from the loading area into the packaging section of the machine. Its primary function is to present products consistently and accurately to the forming box and sealing system while maintaining the required product spacing.

Depending on the application, an infeed conveyor may be manually loaded or automatically supplied by upstream production equipment.

Inverted (Top Seal) Flow Wrapper

An Inverted Flow Wrapper, also known as a Top Seal Flow Wrapper, is a horizontal flow wrapper in which the longitudinal fin seal is positioned on the top of the package rather than underneath it. This machine configuration allows products to travel on a smooth section of packaging film instead of over the longitudinal fin seal.

Top seal flow wrappers are commonly used for delicate products, sticky foods, chocolate-coated items and products where minimising contact with the longitudinal seal improves handling or package presentation.

J

Jaw Diameter

Jaw diameter, also referred to as cutting head diameter, is the distance between the outer paths of the upper and lower rotary sealing jaws or cutting heads on a horizontal flow wrapper. It is an important mechanical specification because it affects product clearance through the cutting head, maximum product height, pack cutoff range and the number of crimpers or jaw sets that can be fitted per shaft.

The correct jaw diameter helps the product pass through the cutting head with adequate clearance and allows the machine to maintain smoother, more constant cutting-head velocity during operation. If the jaw diameter is not appropriate for the product height or cutoff length, the machine may require more speed change or pause during the sealing and cutting cycle, which can limit performance and consistency.

L

Longitudinal Seal

A longitudinal seal, also known as a fin seal, is the continuous seal created along the length of a flow wrapped package where the two edges of the packaging film overlap. The seal is typically formed by heated fin seal wheels as the product travels through the machine.

The quality of the longitudinal seal is critical to package integrity, product protection and overall package appearance. Consistent film tension, correct temperature, sealing pressure and accurate film tracking all contribute to producing a reliable longitudinal seal.

Low-Budget Flow Wrapper

A Low-Budget Flow Wrapper is a flow wrapper designed primarily to achieve the lowest possible purchase price. Depending on the manufacturer, this may involve different engineering philosophies, levels of automation, component selection, machine flexibility or long-term production capability.

Low-budget flow wrappers can be an appropriate solution where production requirements are modest and minimising initial capital expenditure is the primary objective. However, buyers should consider the total cost of ownership, including reliability, productivity, maintenance, local support, spare parts availability and future production requirements when comparing machines.

M

Medium-Range Flow Wrapper

A Medium-Range Flow Wrapper is one category of industrial flow wrapper designed to provide increased flexibility, automation and production capability compared with an industrial entry-level flow wrapper. Medium-range machines typically incorporate additional features that improve versatility, product handling and operating efficiency while maintaining industrial engineering standards.

This is generally the product range where features such as automatic infeed systems, automatic film splicing, expanded recipe management, enhanced diagnostics and higher levels of automation become available. However, the exact features offered vary between manufacturers and machine models.

Modified Atmosphere Packaging (MAP)

Modified Atmosphere Packaging (MAP) is a packaging process that replaces the air inside a package with a controlled mixture of gases before the package is sealed. Depending on the product being packaged, gases such as carbon dioxide, nitrogen and oxygen are used to help extend shelf life and maintain product quality.

Flow wrappers used for modified atmosphere packaging are typically equipped with gas flushing systems and require suitable barrier packaging materials capable of retaining the modified atmosphere throughout the product's intended shelf life.

N

No Product No Bag

No Product No Bag, sometimes referred to as Packless or No Product, No Pack, is a control function that prevents a flow wrapper from producing an empty package when a product is missing or incorrectly positioned.

The system monitors product detection using one or more sensors and automatically inhibits the sealing jaws or film feed when no product is present. This helps reduce film waste, prevents empty packs from entering downstream equipment and improves overall packaging efficiency.

The exact operating method varies between machine manufacturers. Some systems inhibit only the cutting cycle, while others temporarily stop the film feed or synchronise the machine until the next correctly positioned product arrives.

P

PLC (Programmable Logic Controller)

A PLC (Programmable Logic Controller) is the industrial computer that controls the operation of a flow wrapper. The PLC continuously monitors machine inputs, processes control logic and manages outputs such as motors, sensors, heaters, pneumatic devices and safety systems.

Modern flow wrappers typically use industrial PLC platforms that allow flexible programming, reliable operation and straightforward integration with other production equipment.

Print Registration Mark

A Print Registration Mark, also known as a registration mark or eye mark, is a printed reference mark applied to packaging film that allows the flow wrapper to accurately position each package relative to the printed graphics.

A photocell detects the registration mark as the film passes through the machine, enabling the control system to automatically adjust the film feed so that logos, text and graphics remain correctly positioned on every package. To learn how registration photocells are taught and adjusted on a flow wrapper, see our guide: How to Teach a Flow Wrapper Photocell.

Product Pitch

Product pitch is the centre-to-centre distance between consecutive products as they travel through a flow wrapper. Maintaining consistent product pitch is essential for accurate package lengths, reliable product transfer and consistent sealing performance.

Product pitch is determined by the infeed system and must be matched to the selected package cutoff length and machine configuration.

R

Registration Photocell

A Registration Photocell, also known as a print registration sensor, registration sensor or eye mark sensor, is an optical sensor that detects printed registration marks on packaging film. The signal from the registration photocell allows the flow wrapper to automatically synchronise the film feed so that printed graphics, logos and text are positioned consistently on every package.

Registration photocells are essential when running printed packaging film, ensuring each package is cut and sealed in the correct position relative to the artwork. Modern servo-controlled flow wrappers continuously monitor the registration marks and automatically compensate for minor variations in film stretch or print repeat, helping to maintain accurate package presentation throughout production.

S

Sealing Jaws

Sealing jaws are the heated rotary or reciprocating components that create the cross seals at each end of a flow wrapped package while simultaneously separating one package from the next. Depending on the machine design, the sealing jaws may incorporate the cutting knife, anvil and sealing pattern required for the application.

The design of the sealing jaws influences seal quality, package appearance, production speed and the range of packaging materials that can be processed successfully.

Servo Motor

A servo motor is a high-precision electric motor used to control machine movements with accurate position, speed and torque feedback. Servo motors are widely used throughout modern flow wrappers to control functions such as the infeed conveyor, film feed and sealing jaws.

Compared with conventional drive systems, servo motors provide improved positioning accuracy, smoother machine operation, faster product changeovers and greater production flexibility.

Top Seal Flow Wrapper

A Top Seal Flow Wrapper, also known as an Inverted Flow Wrapper, is a horizontal flow wrapper in which the longitudinal fin seal is positioned on the top surface of the package rather than underneath it. This configuration allows products to travel on a smooth section of packaging film and is commonly used for delicate, sticky or chocolate-coated products where improved product handling is required.

Continue Learning About Flow Wrappers

Understanding flow wrapper terminology is only one part of selecting, operating and maintaining packaging equipment. If you're researching flow wrappers in more detail, the following resources provide additional technical guidance and practical buying advice.

• Flow Wrapper Parts Explained – How a Flow Wrapper Works – Learn how the major components of a horizontal flow wrapper work together to form, seal and cut individual packages.

• Flow Wrapper Training – Access practical training resources covering flow wrapper setup, operation, troubleshooting, maintenance and best practices to help operators and maintenance teams improve machine performance.

• Flow Wrapper Buying Guide – Learn how to evaluate different flow wrapper designs, engineering standards and supplier support before purchasing a machine.

• Entry-Level vs Low-Budget Flow Wrappers – Understand why these commonly used terms describe different engineering philosophies and why the distinction matters when comparing machines.

• Flow Wrapper Safety Guide – Learn about machine guarding, safety systems, risk reduction and the key safety considerations when operating horizontal flow wrappers.

• Flow Wrapper Installations Across Australia & Papua New Guinea – Explore real customer installations across a wide range of food manufacturing applications.

This glossary is continually updated as additional flow wrapper terminology and technical definitions are added.

Practical Flow Wrapper Troubleshooting

Understanding the terminology is one thing. Diagnosing and solving real production problems is another.

KWIK TECH GEMS™ is PacMatix's growing library of real-world technical troubleshooting articles, sharing practical solutions developed from servicing, commissioning and supporting packaging machinery throughout Australia and Papua New Guinea. Topics include print registration, sealing problems, fault diagnosis, machine adjustments and other practical engineering tips for flow wrappers and packaging machinery.

See Flow Wrappers in Real Production

Theory and technical knowledge are only part of selecting the right packaging equipment. Explore real customer installations and case studies demonstrating how different flow wrappers are applied across a wide range of food manufacturing environments.

• Flow Wrapper Installations Across Australia & Papua New Guinea – View installations across bakeries, fresh produce, confectionery, snack foods and other food manufacturing applications.

• Flow Wrapper Case Studies – Read detailed customer case studies showing how different packaging challenges have been solved using industrial flow wrappers, including commissioning, operator training and long-term operational outcomes.