The crucial step in applying shrink sleeve labels to your product container is using an appropriate shrink tunnel. Selecting the right shrink tunnel is essential to achieve the best final appearance, so knowing how to choose the correct tunnel is essential. Shrink tunnels come in various types, each with unique benefits. The primary ones include Electric heat shrink tunnels and Steam shrink tunnels. Sometimes a mixture of heat types, like steam shrink tunnels with electric heating zones, might be selected. We posted this article to help you identify the best tunnel type for your product’s container.
Understanding Shrink Films
Before choosing suitable shrink tunnels, we need to learn more about shrink films. Shrink films are primarily made from polymer plastic film, the most common of which are PVC, PETG, OPS, and PLA. Each of these materials has strengths and weaknesses, and selecting between them depends on the product’s specific requirements to be labeled.
One of the critical factors of shrink films in choosing a shrink tunnel is the percentage of shrink required for your product’s container. Typical shrink percentages are up to 55%, while some containers need a high shrink up to 65-70%. These require different shrink films and a high-precision tunnel for superior results. Determining and using a suitable film grade is vital to the success of your project. Choosing the wrong film for your labels could result in expensive production time, wasted materials, and potential loss of products.
Electric Heat Shrink Tunnel–Dry Heat Tunnels
Some products that require a dry labeling environment or sterile environment suit the dry heat shrink tunnels. However, controlling shrink films in dry heat is challenging. They can shrink rapidly and are more distorted than steam shrink tunnels. But Preheating containers might improve shrinking quality in electric heat shrink tunnels.
— Issues with Pigment Concentration
A downside of dry, hot air tunnels is the uneven shrinkage of the sleeve in parts, leading to pigment concentration. Steam tunnels prevent this issue by ensuring even and accumulative shrinking.
— Effects on Empty Plastic Bottles
Electric heat shrink tunnels can distort or melt empty plastic bottles due to high operational temperatures.
Therefore, when we use the electric heat shrink tunnel, we must pay special attention to formulating the shrink tunnel plan. It is necessary to comprehensively consider the relationship between the product container, production speed, shrinkage temperature, and tunnel length and find the most suitable solution so that the product can achieve a perfect shrinkage effect when it passes through the electric shrink tunnel.
Steam Shrink Tunnels
Steam shrink tunnels are the most versatile and practical for shrinking full-body sleeve labels. They provide high-quality shrink results on complex containers like an oval, hourglass, tapered, and offset neck shapes. They are suitable for full and empty containers and cold-filled packages.
Steam is more efficient at transferring heat than dry heat. Steam shrink tunnels usually run at 175 – 200 degrees F, while dry heat tunnels must operate at 350 – 500 degrees F to get similar results. Steam is also accommodating as a single setting of a steam tunnel can often be used for all label colors, while dry heat tunnels may need adjustment again for various colors.
— Disadvantages of Using Steam
A stable steam supply at a moderate pressure is necessary, which may require in-plant steam, or the installation of a steam boiler, typically 48 to 174 KW (4.8 to 17.4 HP) in size. Boilers can be powered by electricity or natural gas. Consider the boiler cost and professional installation by a licensed plumbing company. With steam tunnels, the product will have minimal moisture vapor or droplets upon exiting the tunnel, which typically evaporates quickly. Sometimes, companies add air knives to dry the containers once they go through the steam tunnel.
Dual Zone/Multi-Zone Tunnels
For an optimal shrink process and an attractive product, it’s common to use dual-zone, multiple tunnels, or multi-zone tunnels for shrink label applications. In high-speed operations, two or more tunnels, either the same or different types, might be used sequentially. A pre-shrunk or post-shrink heater unit can be combined with the tunnels for special applications. Using multiple zones allows for targeted heating at specific package points, with varying temperatures, to achieve the desired effect.
Usually, the first zone focuses on the package base to secure the label under a bottom radius to prevent lifting. Secondary zones target the package body and critical graphic areas. Final zones, often multiple, can concentrate on the neck area, where the highest shrink percentage is typically needed, like on wine, beer, or trigger spray bottles.
Testing is Essential
Ensure future shrink tunnel suppliers conduct tests and provide samples and a video. This will require you to provide containers, caps, and sleeves from your selected material supplier. Although it involves some effort, the tunnel you buy will produce the desired result once installed in your facility.
In Summary
Selecting the right shrink tunnel is critical in applying shrink sleeve labels to your product. The type of shrink tunnel depends on the required shrink percentage and involves choosing between dry heat tunnels, dual/multi-zone tunnels, and steam tunnels. Each type has advantages and challenges; sometimes, a combination can be beneficial. It’s essential to understand the nature of your product, the shrink film required, and other factors such as package shape and material. A crucial part of the process is conducting thorough tests with potential suppliers to ensure the tunnel will deliver the desired results once installed in your facility.
When it comes to choosing the right shrink tunnel for your business, there are two main options to consider: steam tunnels and electrical tunnels. Both have their advantages and disadvantages, so it's important to evaluate your specific needs and requirements before making a decision.
Steam tunnels use steam as the heat source to shrink the film around the product. They are known for their efficiency and ability to quickly heat the film. On the other hand, electrical tunnels use electric heating elements to achieve the same result. They are often preferred for their ease of use and lower maintenance requirements.
To choose the right shrink tunnel, consider factors such as the size of your operation, the type and volume of products you need to shrink wrap, and your budget. Additionally, take into account your facility requirements and the shrink ability of each type of tunnel.
Calculating the total cost of ownership is crucial when comparing steam and electrical shrink tunnels. It's not just about the initial purchase price, but also the long-term costs associated with maintenance, energy consumption, and film waste.
Steam tunnels generally have a higher upfront cost compared to electrical tunnels. However, they can be more cost-effective in the long run due to lower energy consumption and reduced film waste. Electrical tunnels, on the other hand, may have lower initial costs but can result in higher energy bills and increased film waste.
To accurately calculate the total cost of ownership, consider factors such as energy efficiency, maintenance requirements, film usage, and potential downtime for repairs. This will help you make an informed decision and choose the shrink tunnel that offers the best value for your business.
Before choosing a shrink tunnel, it's important to analyze your facility requirements. Consider factors such as available space, power supply, and ventilation.
Steam tunnels typically require more space compared to electrical tunnels due to the need for a separate boiler or steam generator. They also require a reliable and sufficient power supply to operate the steam generator. Additionally, proper ventilation is necessary to remove excess steam and prevent moisture buildup in the facility.
On the other hand, electrical tunnels are generally more compact and require less space. They can be easily integrated into existing production lines without significant modifications. However, it's still important to ensure that your facility has the necessary power supply to operate the electrical tunnel.
By analyzing your facility requirements, you can determine which type of shrink tunnel is the most suitable for your workspace and ensure smooth operations.
The shrink ability of a tunnel is an important factor to consider when choosing between steam and electrical options. Shrink ability refers to the tunnel's ability to effectively shrink the film around the product, resulting in a tight and secure wrap.
Steam tunnels are known for their excellent shrink ability. The steam heat evenly distributes throughout the film, ensuring a consistent and tight wrap. This is especially beneficial for irregularly shaped products or those with sharp edges.
Electrical tunnels also provide good shrink ability, but it may vary depending on the specific model and design. It's important to evaluate the performance of electrical tunnels in terms of shrink quality and consistency before making a decision.
Assessing the shrink ability of both steam and electrical tunnels will help you determine which option can deliver the desired results for your products.
Understanding shrink films is essential when choosing a shrink tunnel. Shrink films are typically made from polyolefin or PVC and come in different thicknesses and strengths.
Polyolefin films are commonly used in both steam and electrical tunnels. They offer excellent clarity, high shrinkage, and durability. PVC films, on the other hand, are primarily used in electrical tunnels. They provide good shrinkage but may not be as durable as polyolefin films.
When selecting a shrink tunnel, consider the type of films you plan to use and ensure compatibility with the chosen tunnel. Additionally, assess the film's thickness and strength to ensure it can withstand the heat and shrinking process.
Exploring shrink films will help you make an informed decision and choose a shrink tunnel that is compatible with your preferred film materials.
Both steam and electrical tunnels have their advantages and disadvantages. Understanding these can help you make a well-informed decision for your business.
Pros of Steam Tunnels:
- Excellent shrink ability for tight and consistent wraps
- Efficient heat distribution for faster shrinkage
- Lower energy consumption
- Reduced film waste
- Suitable for irregularly shaped products or those with sharp edges
Cons of Steam Tunnels:
- Higher upfront cost
- Require additional space for a separate boiler or steam generator
- Need proper ventilation to remove excess steam
- Potential maintenance requirements for the steam generator
Pros of Electrical Tunnels:
- Ease of use and lower maintenance requirements
- Compact size for easy integration into existing production lines
- Suitable for a wide range of products
- Lower initial cost
Cons of Electrical Tunnels:
- Higher energy consumption
- Increased film waste
- Shrink ability may vary depending on the specific model
By weighing the pros and cons, you can determine which type of tunnel aligns with your business goals and requirements.