Whether wrapping pallets for shipping or securing products for storage, understanding the various types of stretch films and their features is crucial to achieving optimal results. In this guide, we’ll cover everything from the differences between cast and blown films to the details about hand film options.
Cast vs. Blown Stretch Film
Stretch film is primarily categorized into two types based on its manufacture: cast and blown. Both have distinct characteristics and advantages, making them suitable for different applications.
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- Manufacturing Process: This film is created using a cast extrusion process where melted resin is extruded onto a chilled roller, forming a thin layer.
- Characteristics: It is known for its clear, glossy appearance and smooth texture, which makes it easier to unwind and handle. The transparency of the cast film is excellent, allowing for easy product identification through the wrap.
- Advantages: The quiet release during application and high stretch capability make it popular for most pallet-wrapping applications. It also provides good tear resistance, although it might be less puncture-resistant than blown film.
Blown Stretch Film
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- Manufacturing Process: This type is produced by blowing heated resin into a bubble, which collapses and rolls. This method gives it a more textured and hazy finish.
- Characteristics: Blown stretch film has superior puncture resistance and film memory, making it ideal for irregular or heavy loads. However, it tends to be noisier during application and is less transparent.
- Advantages: Its strength and elasticity make it suitable for demanding applications, especially when transporting heavy or sharp-edged products.
Choosing Between Them: Cast film is the best choice if visibility and ease of use are priorities. Blown film is often the better choice for challenging loads that require higher puncture resistance.
Cling
Cling refers to the stretch film’s ability to adhere to itself, securing the load. Depending on the application, stretch films can be manufactured with one-sided or two-sided cling.
- One-Sided Cling: This is designed for situations where the film should stick to itself but not to adjacent surfaces or other wrapped pallets. This is especially important when pallets might be stored close together to prevent them from sticking together.
- Two-Sided Cling: This type has cling properties on both sides, ensuring a tight hold and effectively securing loads during transport. It is commonly used when pallet stability is crucial, as it improves the wrapping strength and load containment.
The right cling type depends on your storage and handling requirements. One-sided cling is perfect for dense storage areas, while two-sided cling offers enhanced load security in transportation.
The difference between hand film and machine film is noticeable on the rolls.
Film Memory
Film memory is a crucial attribute in stretch films. It describes the film’s ability to recover its original shape after being stretched. High memory means that once the film is applied, it will shrink and hold the load tightly over time.
Why It Matters: Stretch film with good memory maintains tension around the product, ensuring stability during storage and transit. This is particularly beneficial for products that might shift or settle as the film adjusts to keep them tightly secured.
Choosing Based on Film Memory: Due to their manufacturing process, blown films generally have better memory than cast films, making them preferable for loads that may experience movement.
18” vs. 30” Film
When selecting a stretch film, width is another important consideration. The most common widths are 20” and 30”, each serving different needs:
18” Film: This width is typically used for smaller or more manageable loads. It is the standard size for hand-wrapping and offers a balance of control and efficiency.
30” Film: Ideal for larger loads, this width is often used with automated wrapping machines to cover pallets quickly. However, it can be heavier and more difficult to handle manually.
Which to Choose: If you are wrapping by hand, 18” film is likely the best option for ease of use. For automated processes or larger loads, the 30” film increases efficiency and reduces wrapping time.
Gauges
The thickness of the stretch film, known as its gauge, significantly influences its performance. Common gauges range from 60 to 120, each with different strengths and applications. However, it’s important to note that not all gauges are equal; the structure and quality of the film play a crucial role in determining its strength and stretch capacity.
Understanding Gauge: The gauge indicates the film’s thickness; a higher gauge typically means a thicker film. For example, an 80-gauge film offers a balance of strength and flexibility, suitable for general applications, while a 120-gauge film provides extra durability for heavy loads.
Not All Gauges Are Equal: Advanced manufacturing techniques and film compositions mean that some very thin gauges can actually be stronger and more stretchable than thicker ones. For instance, certain high-performance 60-gauge films, although thinner, may outperform traditional 80-gauge films. These films can stretch up to 300%, using much less material to secure a load while providing the same or even greater stability.
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- Cost Consideration: Although these thinner, high-performance films might have a higher price per roll, they often result in cost savings in the long run because they use less material and reduce waste. When evaluating the total cost of securing a load, it’s essential to consider the film’s stretch capacity and load retention rather than just the gauge thickness alone.
Choosing the Right Gauge:
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- Light Loads: For lighter or smaller items, a thinner gauge like 60 or 70 might be sufficient, reducing material costs and waste, especially when opting for a high-performance film.
- Heavy Loads: Thicker gauges (100-120) are more appropriate for heavy or irregularly shaped loads where additional puncture resistance is needed unless a high-performance thin gauge can provide the necessary strength.
Selecting the correct gauge and understanding the film’s properties ensures the film provides the right amount of tension and protection while optimizing costs and material usage. Selecting the correct film gauge is as easy as contacting us!
Hand Film: Pre-Stretched vs. Normal
Hand film is a commonly used option for manual wrapping. It comes in two varieties: pre-stretched and regular.
Normal Hand Film:
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- Requires manual stretching during application, offering greater control over tension and load stability. However, this can lead to fatigue, especially when wrapping multiple pallets.
- It is best when maximum tightness is needed and the user can exert consistent force while wrapping.
Pre-Stretched Hand Film:
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- This film is stretched during production, making it lighter and easier to handle. It reduces the physical effort required and speeds up the wrapping process.
- It is particularly beneficial for frequent use, as it minimizes user strain and offers consistent wrapping with less effort.
Which is Better?: Pre-stretched film is ideal for quick, efficient wrapping without much exertion, while normal hand film works well when more tension and a tighter wrap are required.