Inside a Horizontal Flow Wrapper: Infeed, Film Path, Jaws and Cutoff

A flow wrapper has two paths that meet at the former: products travel along the infeed, through forming and sealing to discharge, while film runs from the reel through the splicer, tension control, registration sensor and coder. This guide divides the machine into five working areas and, for each, lists what it needs from the line and what it hands on. It is compiled from manufacturers’ public pages, cited in the sources section, and is not based on our own tests.

Key points:

• Pack rate is set by the cycle: at a given film speed, a longer film index means fewer packs per minute, and the infeed must deliver products at the matching pitch.
• The film path connects the wrapper to the film supplier and the coding system, through reel size, splices, registration marks and code triggers.
• Seal quality depends on temperature, pressure, dwell time and the film. Jaw type (rotary or box-motion) is a choice to confirm by trial.
• Rejects and downstream capacity have to be agreed between the wrapper, inspection devices and the cartoner or case packer.
• Published speeds are maximums with unstated conditions, so they cannot be compared across models.

What does a flow wrapper do in one pass?

A flow wrapper pulls film from a reel, forms it into a tube around products that arrive in a line, seals the tube lengthwise, then seals and cuts across the tube between products. Syntegon describes its Pack 103 as a horizontal form-fill-and-seal (HFFS) machine that wraps products in rollstock film and seals them on all sides, and calls the resulting pack style flow wrap.

The difference between flow wrapping and overwrapping, and when each format fits, is covered in our flow wrapping vs. overwrapping comparison. This guide assumes the format is already chosen and looks at the machine itself.

Station	What happens there	Main parts
1. Infeed	Products are spaced, timed and pushed into the film tube	Infeed conveyor, lugs or pushers, belt feeders, manual loading section or robot cell
2. Film path	Film is unwound, kept under tension, positioned to the print and coded	Reel holder (backstand), splicer, rollers, tension control, registration sensor, coder
3. Forming and fin seal	Film is folded into a tube and joined lengthwise	Former (forming box), fin wheels
4. End seals and cutoff	The tube is sealed across, before and after each product, and cut	End-seal jaws (crimpers), knife
5. Discharge	Finished packs leave the machine and faulty packs are removed	Discharge belt, reject device

Infeed: where is the machine’s pace set?

The infeed sets the pace because the wrapper can only make a pack when a product is in the right place. Products must arrive one at a time or in fixed groups at a consistent spacing, called pitch, in the orientation the pack needs. If the upstream line cannot hold that pitch, the wrapper slows, stops or makes faulty packs.

A guide from flow wrapper builder Wolf-Packing (December 2025) defines packages per minute as the number of complete wrap cycles in 60 seconds, and pitch as the center-to-center distance between products on the infeed conveyor. It describes film index, the length of film advanced per cycle, as product length plus seal width plus clearance. At a given film speed, a longer film index takes longer to advance, so each cycle is longer and fewer packs are made per minute. The slowest operation in the cycle sets the maximum speed.

Infeeds range from a hand-loaded conveyor to robot cells. Two published examples show that range:

• Manual loading. For the entry-level Pack 103, Syntegon’s product page (checked October 7, 2026) lists infeed lengths matched to the number of operators: 1.5 m for one operator, 3 m for two, 4.5 m for three, 6 m for four and 7.5 m for five. Its page introduces these as three lengths but lists five, so confirm the current options with the supplier.
• Automated feeding. For the washdown Pack 403 HE, Syntegon lists robotic loading across one or several legs, distribution to several legs, grouping and stacking for multipacks, collating, buffering, gap closing and metering, product orientation and pre-turning, and cardstock feeders for product support.

Both machines are offered in left-to-right and right-to-left versions, so the direction of flow is a layout choice that has to be fixed early.

What the infeed needs from upstream:

• Product at the agreed pitch and orientation, or a feeder that creates them, such as gap closing, metering and turning.
• A buffer, or an agreed reaction, for when the upstream supply pauses, so the wrapper does not run empty.
• Agreement on what happens to a missing or misplaced product. Wolf-Packing describes features often called “no product, no bag” and misplaced product detection, which are meant to avoid empty packs and product caught in seals. Ask whether they are standard on the machine you are offered.

If the line has a pace problem rather than a wrapper problem, the bottleneck guide shows how to tell from machine state times which machine limits output.

Film path: what keeps the film running and in register?

The film path determines how often the machine stops for film and whether print, seals and cuts land in the right place. Its parts are the reel holder, an optional splicer, guide rollers, tension control, the registration sensor and often a coder. Each one connects to something outside the machine: the film supplier, the print layout or the coding system.

• Reel holder and splicer. Syntegon’s 2020 release for the Pack 202 lists a 450 mm dual backstand as standard and a 650 mm single backstand as an option, plus an optional automatic film splicer for changing reels without stopping the machine. Whether a reel change on your machine needs a stop depends on the splicer fitted, so confirm it. Also confirm how the splice passes through the seals and cutoff, and whether packs containing the splice are detected and rejected.
• Rollers and threading. The same release describes sequentially numbered film rollers that make threading repeatable at changeover. If threading is done from memory, film path errors become a changeover problem.
• Tension. Film must reach the former at a steady tension. Wolf-Packing describes dancer arms or load cells adjusting brake torque to hold tension across the speed range. Ask which method your machine uses and how it is set for each film.
• Registration sensor. On printed film, a sensor reads an eye-mark so the cut and the end seals fall at the right point in the print. Soontrue’s maintenance guidance (May 2026) notes that dust or film particles on photoelectric and eye-mark sensors can cause false stops or misalignment, and in the worst case the knife cuts into the product.
• Coder. Syntegon lists batch coding and expiration date printing among the Pack 103 options. Where the coder is mounted, how it is triggered and how code content reaches it are not described on public pages, so confirm them with both the wrapper and coder suppliers.

The film interface has its own checklist. The properties a film supplier must document, including friction, tension range, registration marks and sealing window, are covered in the film and machine compatibility guide. If code legibility or print register will be checked by a camera, the machine vision guide explains what a vision station can and cannot verify.

Forming and the fin seal: how is the lengthwise seal made?

The former folds the flat film into a tube around the product, and the fin wheels pull the two film edges together and seal them along the length of the pack. That lengthwise seal is the fin seal, and it usually sits on the underside of the finished pack. Fin wheels also help transport the film, so they affect film travel as well as seal quality.

In a February 2026 article on sealing and cutting, Syntegon describes fin wheels as giving precise film guidance and constant film transport at synchronized speed, which reduces slippage and wrinkles while forming an airtight fin seal. In its 2020 Pack 202 release, the same company describes fin modules that operators can tilt (cant) with a knob. On the Pack 403 HE, it lists finwheel pressure gauges among the visual controls.

Sealing depends on the film as much as on the machine. Syntegon states that reliable seals need the right combination of temperature, pressure, sealing time and film type. For the Pack 103, it lists cold-seal film for heat-sensitive products such as chocolate and heat-seal film where a hermetically sealed pack is needed. Which applies to your product is a film and pack decision, made before the machine settings.

End seals and cutoff: what do the jaws and the knife do?

The end-seal jaws, also called crimpers, seal across the film tube behind one product and in front of the next. A knife then cuts between the two seals. Each pack gets a trailing seal from one jaw closure and the next pack gets its leading seal from the same closure. Seal quality and pack length are both decided at this station.

Syntegon describes the jaws as delivering consistent temperature, uniform pressure and a defined dwell time. It places the knife after the sealing unit, cutting in coordination with the jaws so that pack length stays consistent and the film does not fray. Its 2020 Pack 202 release describes a double-spring kit on the cross-seal unit for more consistent seals, with finer crimper adjustment. Check the current configuration with the supplier.

Jaw motion is the main design split. Rotary jaws turn continuously. Box-motion jaws move in a rectangular, back-and-forth path, which Soontrue says gives a longer dwell time. The table summarizes how Soontrue describes the difference. These are a manufacturer’s descriptions, not test results, and the right choice for a given product is settled by a trial.

Point	Rotary jaws	Box-motion jaws
Motion	Continuous rotation	Rectangular, back-and-forth movement with the film
Seal dwell time	Shorter than box-motion	Longer dwell time per cycle
Products described as suited	Uniform products in continuous, high-volume runs	Taller, delicate, irregular or multipack products
What to verify	Seal integrity on your film at target speed	Whether the extra dwell is needed for your film and pack, and at what speed

Sealing technology also varies within a builder’s range. Syntegon, for example, lists rotary cold and hot sealing, its AHS hot sealing, rotary ultrasonic, and LongDwell hot or ultrasonic sealing as options to evaluate with the product. End seal styles also vary. Syntegon lists straight, zig-zag and serrated end seals, and notes that vertical seal serrations need a tailored jaw setup. Jaws and knives are wear parts, so put them on the spare parts list from the start.

When seals fail in production, the seal defect investigation checklist shows how to collect evidence before changing settings, so a film problem is not treated as a jaw problem.

Discharge and reject: what must the wrapper hand over?

The discharge belt takes finished packs away from the cutoff and passes them to inspection, collation or a cartoner. Faulty packs have to leave the line here or at the next inspection point. Before ordering, agree on which machine detects which fault, which device rejects it and how the reject is confirmed.

Syntegon’s 2020 Pack 202 release describes a one-meter reject belt and a detection function on the short discharge belt that ejects faulty packages with compressed air. For larger and heavier products, a two-meter discharge module with a reject plow is offered as an option. Your machine may differ, but the questions are the same. What does the wrapper detect itself? What does a downstream checkweigher, metal detector or camera detect? How does each reject get confirmed?

Downstream capacity matters as much as the reject. Wolf-Packing notes that downstream equipment has to clear packs faster than the wrapper makes them. Without accumulation, any downstream stop forces the wrapper to stop. Syntegon’s 2020 account of a cracker line shows the handover in one project: flow wraps go straight to a TTM 100 topload cartoner that the company says loads 30 to 150 packs into cartons per minute. That figure belongs to that machine and project. It shows that the cartoner’s range and the wrapper’s output have to be matched in the line design.

Inspection order and reject handling are covered in the checkweigher and metal detector guide. Loading into cartons and cases is covered in the cartoner and case packer comparison.

Station-by-station interface map

Every station on a flow wrapper either receives something from outside the machine or hands something over to it. The table lists those interfaces so you can assign each one to the wrapper supplier, a neighboring supplier or your own team, and decide how it will be verified. Use it alongside a general interface list such as the packaging line integration checklist, which covers electrical, signal, safety and utility interfaces in more depth.

Station	What it does	Needs from upstream or suppliers	Hands to the next step	Confirm before ordering
Infeed	Spaces and times products into the film tube	Product at agreed pitch and orientation; supply rate and pauses; group size for multipacks	Products in register with the film	Infeed type and length; flow direction; reaction to missing or misplaced product; buffer location
Film path	Unwinds film, holds tension and keeps print in register	Reel width, core and diameter range; splice method; registration mark position and contrast	Film in tension and in register	Backstand and splicer type; tension method; registration sensor type; threading guide
Coder (part of the film path)	Prints batch and date codes	Code content and trigger; coder mounting space	Coded film or pack	Who supplies the coder; how it is triggered; how a missing or bad code is detected
Forming and fin seal	Folds film into a tube and seals it lengthwise	Film with a documented sealing window; product height and width range	Sealed tube	Former range and change parts; fin seal type (heat or cold seal)
End seals and cutoff	Seals across the tube and cuts single packs	Pack length; seal style; film sealing window	Single packs of consistent length	Rotary or box-motion jaws; sealing technology; end seal style; jaw and knife spares
Discharge and reject	Carries packs away and removes faulty ones	Downstream rate and accumulation; inspection devices and their reject signals	Good packs to collation, cartoner or case packer	What the wrapper rejects itself; reject confirmation; discharge length and height; status signals to neighbors

Integration problems and where they start

A problem can show up at one station but start at another, often at an interface. The table pairs symptoms described in the manufacturer sources cited here with the interface to check first. It is an author’s checklist, not a diagnosis of any particular machine.

Symptom	Where it often starts	Check first
Empty packs or product caught in the end seal	Infeed pitch or a missing product upstream	Product spacing at the infeed; whether missing-product detection is active
Cut or seal lands in the wrong place on the print	Registration sensor or film print	Sensor cleanliness and setting; registration mark position and contrast on the film
Frequent stops at reel change	Film path	Whether a splicer is fitted; reel size against shift length
Wrinkled or open fin seal	Fin wheels or film	Fin wheel pressure and temperature or cold-seal setting; film within its documented sealing window
Leaking end seals at speed	End-seal jaws or film	Dwell and temperature against film data; jaw type for the product height
Wrapper stops when the cartoner stops	Discharge and downstream	Accumulation between machines; status signals between wrapper and cartoner
Rejects end up in the good stream	Reject device or confirmation	Reject confirmation sensor; which machine owns each reject
Long changeovers	Change parts and settings	Which parts change by format; whether settings are stored as recipes

Two background points help with the last rows. Wolf-Packing describes wrappers in which the infeed, film feed and jaws are separate servo axes coordinated by a central motion controller, which is why format changes can be partly recipe-based. The servo and pneumatic actuation guide explains how that affects changeover. For the changeover itself, the format changeover checklist lists what to record so a change is repeatable.

What do the published speed figures tell you?

Published speeds are manufacturer maximums for a model. They do not tell you what a line will produce with your product, film and pack length. Use them to see which class of machine a supplier is offering, then ask for the conditions behind the number.

Model	Published speed	Other published configuration	Source and date	Conditions stated
Syntegon Pack 103	Up to 175 packages per minute	Manual or semi-automatic loading; five infeed lengths for one to five operators; left-to-right or right-to-left	Syntegon product page, checked 2026-10-07	Product, film and pack length not stated
Syntegon Pack 202	Not stated in the source; described as for low to medium speeds	450 mm dual backstand standard, 650 mm single optional; optional automatic splicer; 1 m reject belt	Syntegon press release, August 14, 2020	Configuration as launched; current options to confirm
Syntegon Pack 403 HE	Up to 600 packages per minute	Washdown design; belt or robotic infeed options; left-to-right or right-to-left	Syntegon product page, checked 2026-10-07	Product, film and pack length not stated

For context, Syntegon’s solutions page describes its range as running from 80 packages per minute at entry level to 1,500 for integrated systems, again without stated conditions.

The figures are not comparable across models or suppliers because the conditions behind them are not published. A quote is comparable only when it states the product, film, pack length and seal type behind its speed. The RFQ checklist shows how to ask for that.

Limits and on-site verification

This guide describes how flow wrappers are generally built and where they connect to a line. Your machine will differ, and these points can only be settled with the real product, film and equipment:

• Infeed behavior. Spacing, orientation and product damage at transfer points show up only in a trial with your product, ideally including the worst-case product.
• Sealing. Fin and end seal settings depend on film, temperature, pressure and dwell. The film supplier and machine builder give ranges, and a test on your film confirms them.
• Jaw choice. Rotary versus box-motion is described differently by different builders. Ask for a trial at your target speed rather than relying on general descriptions.
• Signals and reject handling. Status signals, reject confirmation and code checks must be written into the specification and tested at acceptance. The FAT and SAT guide covers how.
• Rated speed. Treat every published figure as a ceiling under unstated conditions until a trial shows otherwise.

Frequently asked questions

How does a flow wrap machine work?

Products enter on the infeed at a fixed pitch. Film is formed into a tube around them and sealed lengthwise by fin wheels, then end-seal jaws seal across the tube and a knife cuts the packs apart. The interface map shows what each step needs from the line.

What are the different types of flow wrap machines?

This guide distinguishes machines first by end-seal motion: rotary jaws or box-motion jaws. Machines also differ by infeed (manual, automatic or robotic), by hygienic design (standard or washdown) and by sealing method (heat, cold or ultrasonic). Which combination fits depends on the product and the film.

Method and sources

This guide was compiled from manufacturers’ public product pages, press releases and technical articles about horizontal flow wrappers. Each claim is attributed to its source in the text. The figures are the manufacturers’ own and were not verified by testing. In a search of US desktop results for “what is flow wrap” on October 7, 2026, the top ten results were product pages, videos and social posts, with no page explaining the machine station by station. That gap is why this guide is organized around stations and interfaces. Models are named only as published examples of a design feature. The guide does not rank or recommend them.

Sources, all accessed October 7, 2026:

• Syntegon, “Pack 103 horizontal flow wrapper”, product page.
• Syntegon, “Pack 403 HE horizontal flow wrapper”, product page.
• Syntegon, “Horizontal flow wrapper”, solutions page.
• Syntegon, “Sealing and cutting for horizontal flow wrappers”, February 12, 2026.
• Syntegon, “New Syntegon Pack 202 Flow Wrapper”, press release, August 14, 2020.
• Syntegon, “The cracker packer”, July 22, 2020.
• Soontrue, “Top 10 Maintenance Tips to Extend the Life of Your Horizontal Flow Wrapper”, May 28, 2026.
• Soontrue, “Rotary Vs Box Motion Flow Packing Machine: What Is The Difference?”, July 5, 2024.
• Wolf-Packing Editorial Team, “Flow Wrapper Speed: Matching Production Line Efficiency”, December 4, 2025.

For where the flow wrapper sits in a complete line, see the overview of packaging machine types and the packaging equipment guides.