Shrink sleeve machines handle PET film sleeves by feeding flat PET-G film from a reel, opening it over a mandrel to form a tube, cutting it to the correct sleeve length, and transferring it down over the container. The sleeve is then shrunk tightly around the product using a steam tunnel. PET-G is the most widely used PET-based material for shrink sleeves because it combines excellent clarity with high shrink rates, making it well suited for complex container shapes.
Understanding how each stage of the process works, and what makes PET film behave differently from other materials, helps you get the best results from your sleeving line. Below, we answer the most common questions about running PET film on a shrink sleeve machine.
What makes PET film different from other sleeve materials?
PET-G film stands out from other shrink sleeve materials because it offers a high shrink rate, excellent optical clarity, and strong recyclability. These properties make it a strong choice for containers with complex shapes or curved profiles, where other materials may not conform as cleanly. It is also more compatible with modern recycling streams than PVC, which has become less favored in markets with strict environmental regulations.
To understand where PET-G sits among the available options, it helps to compare the most common shrink sleeve films side by side:
- PVC: Widely used and cost-effective, with easy printability and low shrink temperatures. Less favored where environmental regulations are strict.
- PET-G: High shrink rate, excellent clarity, and good recyclability. Well suited for complex container shapes and sustainability-focused production.
- OPS: Lightweight with good clarity and moderate shrink performance. Commonly used in food and beverage packaging.
- OPP: High clarity and stiffness, but a lower shrink rate. Best suited for containers with simpler profiles.
- PLA: Bio-based and renewable, with good printability. Shrink performance varies by grade, but it supports sustainability targets.
- PE and PP: Flexible, durable, and recyclable. Lower shrink characteristics, used where toughness and recyclability matter more than conformability.
- Polyolefin films: A broader category covering PE- and PP-based materials, valued for recyclability and a favorable environmental profile.
PET-G’s combination of high shrink performance and recyclability makes it a practical choice for producers who need both visual quality and a more sustainable material profile. The trade-off compared to PVC is that PET-G requires higher shrink temperatures, which means your tunnel settings and steam pressure need to be calibrated accordingly.
How does a shrink sleeve machine apply PET film sleeves?
A shrink sleeve machine applies PET film sleeves through a sequence of precisely coordinated steps: the flat film is fed from a reel, opened into a tube over a shaped mandrel, cut to the correct sleeve length by a rotary cutter, and pushed down over the container using sleeve transfer rollers. A tacking unit then lightly pre-shrinks a small area of the sleeve to hold it in position before the container enters the shrink tunnel.
Here is how the full process flows in practice:
- Film feed: Flat PET-G film is unwound from a reel and fed into the applicator. A continuous reel unit can automatically splice a new reel when the active one nears its end, keeping production running without interruption.
- Mandrel forming: The flat film is opened over a mandrel, a shaped spear that dilates the film into a tube matching the container’s diameter.
- Cutting: A rotary cutter trims the film to the exact sleeve length set in the machine recipe. You can fine-tune the cut length during production if needed.
- Sleeve transfer: Transfer rollers push the cut sleeve down over the container as it passes beneath the mandrel.
- Sleeve positioning: A positioning unit brushes the sleeve to the correct vertical height on the container.
- Tacking: Hot-air nozzles lightly shrink a small portion of the sleeve to prevent it from shifting during transport to the shrink tunnel.
- Inspection: Sensors check every container for sleeve presence and correct sleeve height. Products that fail this check are ejected automatically before entering the tunnel.
Registration marks printed on the film help the machine align each sleeve correctly. A photocell reads these marks to ensure the printed design lands in the right position on every container.
What type of shrink tunnel works best for PET sleeves?
A steam shrink tunnel works best for PET-G film sleeves. Steam delivers even, controlled heat across the entire sleeve surface, which is important for PET-G because it has a relatively high and consistent shrink rate. This even heat distribution helps the film conform tightly to complex container shapes without distortion or wrinkling.
Steam tunnels allow you to adjust settings independently for each section of the tunnel, including steam volume, nozzle angle, and extraction rate. This level of control is particularly useful with PET-G, where precise temperature management directly affects shrink quality. The operating steam pressure typically needs to stay within a defined range, for example between 3.5 and 4.0 bar, to achieve consistent results without over-shrinking or distorting the sleeve.
Hot-air tunnels are an alternative, but they are generally better suited to materials with lower shrink requirements. For PET-G, where you need higher and more uniform heat, steam is the more reliable option. If you run multiple film types on the same line, a steam tunnel with adjustable section settings gives you the flexibility to adapt to each material’s specific shrink behavior.
Why does PET film shrink unevenly, and how is it prevented?
PET film shrinks unevenly when heat is not distributed consistently across the sleeve surface. The most common causes are misaligned or unevenly set steam nozzles, insufficient steam pressure, or incorrect nozzle angles. Because PET-G has a higher shrink rate than many other materials, any variation in heat delivery is amplified in the final result, producing visible wrinkles, incomplete shrink zones, or distortion.
Preventing uneven shrinkage comes down to correct tunnel setup and consistent maintenance:
- Balance nozzle settings: Both nozzles within each tunnel section must be set equally. Unequal settings create hot and cool zones that cause the sleeve to pull unevenly.
- Maintain correct steam pressure: Running below the recommended pressure range results in incomplete shrink. Running too high causes over-shrink or distortion. Staying within the specified operating range is important for consistent output.
- Adjust steam volume per section: Different parts of a container, such as the shoulder or base, may need more or less heat. Independent section control lets you fine-tune the heat profile for each product format.
- Use camera inspection downstream: A camera system after the tunnel detects products with shrinkage defects such as wrinkles or incomplete coverage and ejects them automatically. This catches problems before products leave the line.
- Record settings per product: Saving the correct tunnel parameters in product-specific recipes means you can reproduce consistent results every time you run the same format, reducing the risk of setup errors after a changeover.
If you are switching from a material like PVC to PET-G, expect to recalibrate your tunnel settings. PET-G requires higher heat input, and settings that worked well for PVC will typically produce incomplete shrink on PET-G film.
Can shrink sleeve machines handle both PET and other sleeve films?
Yes, most modern shrink sleeve machines can handle PET-G alongside other sleeve films such as PVC, OPS, OPP, and polyolefin materials. The machine hardware, including the mandrel, rotary cutter, and transfer system, is generally compatible with all common film types. What changes between materials is the tunnel configuration, steam settings, and in some cases the mandrel size if the film width differs.
Switching between film types on the same machine is straightforward when the changeover process is well managed. If you are changing to a different film width, you will need to replace the mandrel and potentially the rotary cutter to match the new format. Changing to a different film type with the same dimensions mainly requires updating the tunnel settings and recipe parameters to reflect the new material’s shrink behavior.
The key practical consideration is that each film type has its own shrink temperature range and behavior. PET-G needs more heat than PVC, while OPS and polyolefin films each respond differently to steam pressure and volume. Storing product-specific conversion sheets with the correct settings for each film type and container format makes it much easier to switch between materials reliably and quickly.
How Sleeve Technology Supports PET Film Sleeving
We design and build shrink sleeve machines that are fully capable of handling PET-G and a wide range of other sleeve film materials. Our machines are built around proven mechanical principles and equipped with advanced control technology, giving you the precision and flexibility needed to run PET film consistently at high efficiency.
Here is what working with us gives you in practice:
- Custom machine configuration: We build machines to match your specific production line, container types, and film requirements, whether you are running PET-G on complex bottle shapes or switching between multiple film types.
- Steam shrink tunnels with independent section control: Our tunnels let you fine-tune steam volume, nozzle angle, and extraction per section, giving you the control needed to achieve consistent shrink quality on PET-G film.
- Continuous reel systems: Our CR6 continuous reel unit automatically splices new film reels without stopping the line, keeping your production running without interruption during reel changes.
- Integrated inspection: Built-in sleeve presence and height sensors, combined with downstream camera inspection, catch defective products before they leave the line.
- 24/7 global support: Our service team is available around the clock, with locally available spare parts and multilingual field engineers ready to support you wherever you operate.
If you want to find out how our shrink sleeve machines can be configured for your PET film application, contact us today and we will help you identify the right solution for your production line.