Packaging-material guide

Flow-wrap films, reel data and seal formats

A film name alone is not enough. Reliable running depends on the complete laminate or mono-material structure, sealant, thickness, friction, stiffness and reel quality.

Information reviewed 16 July 2026 by Lancing Ltd.

Machine selection support Flow wrapping film path and machine category image

Specify the complete film construction

The published LUZB350X data names OPP, OPP/CPP, KOP/CPP, aluminium film and bubble wrap. The wet-wipes listing names PE, OPP, PET-paper film and aluminised or composite structures. These are broad material families, not a finished packaging specification.

Provide the supplier data sheet, total thickness, individual layers, sealant side, coefficient of friction, reel width, maximum diameter, core size, unwind direction and any print registration details.

Longitudinal and end seals

A horizontal flow wrapper forms a tube around the product using a longitudinal seal, then uses transverse jaws to create the pack ends and cut between packs. The listed LUZB350X configuration describes a middle side seal with top end seals.

Fin seal

The two inner sealant surfaces meet face-to-face. This can provide a robust and predictable seal but creates a projecting fin that must be guided beneath or above the pack.

Lap seal

One web edge overlaps the other. It can reduce the visible seal profile, but the film must support sealing across the overlapping surfaces and the machine must be configured accordingly.

Printed film and registration

Photoelectric registration detects a printed eye mark and adjusts cut position so artwork remains aligned with the pack. Supply artwork repeat, mark dimensions, contrast, location, unwind orientation and permitted print-to-cut tolerance.

Sealability and hot tack

The seal needs enough heat, pressure and dwell time to close reliably at production speed. Hot tack describes how the seal behaves while still warm. Product contamination, wrinkles and jaw alignment can all reduce seal quality.

Material reduction and recyclability

Downgauging or moving to a mono-material structure may improve material efficiency, but only if the new film forms, tracks and seals across the required speed range. Packaging sustainability should be evaluated across material use, product protection, waste, transport and the actual local recovery route.

Reel checklist

Film information for a quotation or trial

Film data to supply
Property	Example information	Engineering effect
Structure	OPP/CPP, PE mono-material, metallised laminate	Sealant compatibility, barrier and stiffness
Thickness	Total microns and layer build	Forming, tension, heat transfer and cut performance
Reel	Width, diameter, core, weight, unwind	Mechanical fit and web path
Surface	Coefficient of friction and treatment	Tracking, forming and product movement
Print	Repeat, eye mark, colours and tolerance	Registration and cut position
Sealing	Temperature range, pressure, dwell and hot tack	Maximum robust operating rate

Machine limits

Check reel width, diameter, product height and pack width against the selected model.

LUZB350X specification

Application fit

Confirm product behaviour and seal cleanliness before committing to a material.

Application guide

Environmental options

Explore related packaging-material information from Lancing’s specialist resources.

Environmental packaging

Frequently asked

Flow-wrap film questions

Which films are listed for the LUZB350X?

The published machine data lists OPP, OPP/CPP, KOP/CPP, aluminium film and bubble wrap. Each proposed material still needs verification for thickness, sealant layer, friction and reel dimensions.

What is the difference between a fin seal and a lap seal?

A fin seal brings the inner sealant surfaces together and leaves a projecting fin. A lap seal overlaps one web edge over the other and requires a structure that can seal across the relevant surfaces. The machine and film must be configured for the chosen style.

Why is the sealing window important?

Production must achieve a secure seal without distortion or burn-through across normal speed and temperature variation. A narrow operating window can limit output and robustness.

Can recyclable film run on a flow wrapper?

Potentially, provided the selected structure has suitable stiffness, friction, hot-tack and sealing performance. Recyclability claims and collection routes must be assessed separately from machine runnability.

Film qualification

Use production film to establish a repeatable sealing window

A material family such as OPP or PE does not define how a reel will form and seal. Trial the complete construction at representative machine speed, then record the settings and pack-quality checks that produce an acceptable result.

Mechanical fit

Confirm reel width, maximum diameter, core, weight, unwind direction and edge condition. The web must fit the unwind and track through rollers, former and fin-seal assembly without uncontrolled movement.

Registration control

Provide repeat length, mark dimensions, contrast, mark position, print orientation and allowed print-to-cut variation. A sensor can only control a mark that remains detectable across the supplied reels.

Seal performance

Map temperature, pressure and dwell time at the required speed. Check both the longitudinal seal and transverse end seals because they can have different heat transfer and contamination risks.

Failure modes

Separate film, setup and product causes during trials

Change one controlled variable at a time and record the result. This creates a usable process window instead of a single setting that may fail when product or ambient conditions vary.

Common flow-wrap symptoms and checks
Symptom	Checks to make	Trial boundary
Weak or open seal	Sealant orientation, temperature, pressure, dwell, jaw condition, film contamination and line speed.	Use the agreed seal test and production film before accepting the setting.
Burn-through or distorted film	Excess heat or dwell, uneven jaw temperature, film thickness and cooling after the seal.	Confirm appearance and strength across the full speed range to be used.
Wrinkles in the end seal	Web tension, former alignment, product position, fin handling, jaw parallelism and pack width.	Test the smallest and largest products and film reels from normal production.
Artwork drifting from the cut	Mark contrast, sensor position, repeat variation, web slip, tension and unwind direction.	Measure print-to-cut variation over a sustained run and after reel changes.
Product in the seal	Pitch, product length variation, crumbs or loose parts, infeed timing and jaw phase.	Include difficult products and the normal upstream arrival pattern.
Film not tracking centrally	Reel winding, edge quality, roller alignment, friction, tension and former setup.	Confirm that correction remains stable rather than relying on frequent operator adjustment.

Material change control

Re-qualify film changes that alter machine behaviour

Changing gauge, laminate, sealant, coating, print, friction or reel construction can change tracking and sealing even when the nominal width is unchanged.

Keep an approved reference

Record the supplier, construction, thickness, reel details, artwork repeat and accepted machine settings for the qualified material.

Compare the proposed change

Ask the film supplier to identify changes to seal initiation, hot tack, friction, stiffness, barrier, coating and winding specification.

Run a controlled trial

Test the revised material with production product at the required output and repeat the agreed seal, registration and pack-appearance checks.

Registration marks and representative reels

What registration mark details should be supplied?

Supply the mark size, colour, contrast against its background, position across the web, distance from the cut, one-pack repeat length, artwork orientation, unwind direction and the acceptable print-to-cut tolerance.

Why should production film be used for trials?

A sample reel made from a different structure, gauge, coating or winding specification may track and seal differently. Production film gives the best evidence for web handling, registration, sealing window and finished-pack appearance.

Printed-film handover

Approve artwork against a machine-ready reel specification

A graphic proof can be visually correct but still unsuitable for the wrapper. Release printed film only after repeat length, registration mark, unwind, seal keep-clear areas and reel construction have been checked against the approved pack and machine web path.

Printed flow-wrap film release sheet
Reel or artwork item	Information to fix	Machine or pack consequence
Web width	Nominal width and permitted tolerance for the approved former and pack.	Too narrow can reduce seal overlap; too wide can affect tracking, folding and excess film around the product.
Print repeat	Distance for one complete pack repeat, linked to the approved bag length and cut position.	A repeat mismatch can force registration correction and move artwork or seals away from the intended position.
Registration mark	Size, shape, colour contrast, lane position and one mark per intended repeat.	The photoelectric sensor needs a clear, repeatable target outside confusing graphics or transparent variation.
Unwind and print side	Reel winding direction, sealant side, print orientation and which face travels through the former.	Incorrect unwind can reverse artwork, expose the wrong sealing surfaces or place the mark outside the sensor path.
Core, outer diameter and reel weight	Core dimensions, maximum diameter, reel width and handling limit for the supplied machine.	The reel must fit the unwind and be loadable using the agreed handling method.
Seal and jaw keep-clear	Areas reserved for the longitudinal seal, end seals, cut, tear feature and any product clearance.	Ink, coatings, text or critical graphics should not conflict with the sealing and cutting zones.
Coding and inspection area	Supported print area, code content, contrast and verification location.	The code must remain legible and visible after forming, and product tracking must link a failed result to the correct pack.
Splices and reel quality	Permitted splice construction, edge quality, telescoping, winding tension and reel identification.	Reel defects can disturb tracking, registration and automatic running even when the laminate itself is unchanged.

Reference and change control

Keep an approved reel and pack as the production reference

Film names such as OPP, PE or laminate do not describe the complete converting result. Retain the exact specification and accepted pack used to establish the format, then compare future deliveries and proposed changes with that reference.

Pre-production proof

Check artwork repeat, mark position, unwind, seal areas and code space before committing the full print run. A visual design approval alone is not a machine approval.

First production reel

Run enough material to establish tracking, registration, sealing, cutting and sustained output. Record reel identification, settings and accepted samples.

Incoming reel check

Verify identity, width, core, diameter, winding, damage and visible print or edge condition before loading. Escalate material that differs from the approved reference.

Controlled change

Re-qualify changes to structure, thickness, coating, sealant, friction, print repeat, converter or reel build when they can affect forming, sealing or presentation.

Can artwork be approved before print repeat and unwind are fixed?

The graphic design can be reviewed, but final machine-ready approval should wait until repeat length, registration mark, unwind, seal keep-clear areas and code position are tied to the approved bag and web path.

Is a short unprinted film trial enough for printed production film?

It can help screen forming and sealing, but it does not prove print registration, artwork-to-cut position, ink or coating effects, final unwind or the consistency of a production reel. Printed production material should be included before the format is released.

What should be checked when the film converter changes?

Compare the complete structure, thickness, sealant, friction, stiffness, treatment, print repeat, registration mark, unwind, core, reel build and tolerances. Run the agreed machine and pack checks before treating the replacement as equivalent.

Why can films with the same nominal material name run differently?

The layer build, sealant, thickness, coefficient of friction, stiffness, coatings, treatment and reel winding can differ even when both films are described as the same broad material family. Those differences affect tracking, forming and the sealing window.

Treat film and machine as one sealing system

A film fault can originate before, inside or after the sealing section

Reel quality, threading, product timing, jaw contact, contamination and downstream handling can produce similar pack symptoms. Use an approved reel and pack to separate material, setup, product and mechanical causes before changing the film specification.

End-seal contact

Compare the proposed jaw motion against the production film, pack height, seal clearance and accepted test method.

Rotary vs box-motion jaws

Fault diagnosis

Trace weak seals, wrinkles, tracking drift and registration faults to the condition and location where they begin.

Troubleshooting guide

Representative proof

Fix the reel, product, settings, run conditions and acceptance criteria before comparing materials or suppliers.

Trial and FAT guide

Requalify changes that alter machine behaviour

A nominally equivalent film can change friction, stiffness, static, hot tack, registration and sealing response. Retain material identity and run a controlled comparison before production release.

Film decisions linked to the complete process

Connect reel data to pitch, atmosphere and coding

Reel width and material name do not define the full duty. Print repeat, seal clearance, barrier, registration and code position must match the approved product and pack.

Pack repeat and product pitch

Relate product length, end-seal allowance and printed-film repeat before artwork and format parts are approved.

Pitch and pack-length guide

Gas-flush film duty

Review barrier and seal integrity as part of a validated product-specific atmosphere system.

Gas-flush packaging guide

Artwork and code area

Keep registration marks, mandatory information and variable coding inside a controlled print and inspection plan.

Coding and inspection guide

From product envelope to reel width

Size the film from the complete finished-pack geometry, not product width alone

Film width must pass around the product and still provide the longitudinal seal, tracking allowance and the selected former geometry. Bag length must include the product, end-seal clearance and the repeat used by printed film.

Measure minimum and maximum product

Record length, width and height in the actual infeed orientation, including toppings, trays, groups and normal variation.

Define the finished pack

Show longitudinal- and end-seal positions, acceptable headspace, cut position, print direction and code area.

Confirm on the selected machine

Use any calculation only as an early estimate, then verify the web, former, seal and print repeat with production film.

Film width and pack-size guide

Qualify the operating range

Questions about flow-wrap temperature, pressure and dwell

A material name does not define the complete sealing recipe. Use the production reel and record the accepted range on the proposed machine.

What is a flow-wrap sealing window?

A sealing window is the range of film, temperature, pressure, contact time and speed conditions that consistently makes an accepted longitudinal and end seal. It should include product variation, normal stops, restarts and the actual jaw and web-control condition.

Why can a seal work slowly but fail at production speed?

Higher speed can reduce available contact time and change heat transfer, web tension, product timing and cooling. A recipe proved on a few slow samples is not enough; qualify the pack over a sustained run at the intended accepted output.

Can a different film run on the same recipe?

Not safely by assumption. Film structure, gauge, sealant, coating, friction and winding can change even when the broad material name is similar. Treat a new film as a controlled change and re-confirm tracking, registration, seals and pack appearance.

Should heat seal or cold seal be used?

The decision depends on product heat sensitivity, film construction, coating registration, machine compatibility and the accepted pack. Cold seal is a separate material and equipment route, not simply a lower temperature setting on every heat-seal wrapper.

Read the complete temperature, pressure and dwell guide