There are several different types of stretch film, intended for different uses. The variety of stretch films are to address common issues such as load size, load weight, load type, etc. There are also other stretch films that address uncommon issues such as UV protection, static reduction, reduced condensation, etc.

Blown stretch film and cast stretch film are the two types of stretch film. Both types of stretch film are manufactured in different ways. They both have different qualities and characteristics. Below is a brief explanation of blown stretch film.

Blown Stretch Film- Blown stretch film is made using the blown extrusion process. The blown extrusion process uses a vertical die that extrudes the plastic melt to form a thin tube. Air is then blown into the center of the tube to form an air bubble with the film. The amount of air blown into the bubble determines the overall width of the finished film. The film is constantly rotating. The speed of the film rotation and how fast the film is being pulled upward determines the thickness of the film.

While traveling upward several feet to the nip rollers, the stretch film begins to cool. Once the bubble hits the rollers it is collapsed into a flat tube. From the rollers, the film moves to another set of rollers. The other set of rollers cut the flat tube into two layers that can each be wound onto their own core. For large width stretch film, one side of the flat tube can be slit to form a large width stretch film.

Advantages- Blown stretch film has a higher load and stretch capacity. Blown stretch film is considered a higher quality of film for load retention. The memory of blown stretch film is superior to cast stretch film. This means that once stretched, blown stretch film stays tighter to the load over a longer period of time. Blown stretch film also has superior tear resistance and is great for wrapping loads with sharp edges.

Disadvantages- Cost is the primary disadvantage of blown stretch film. The manufacturing process cost more, therefore the cost of blown stretch film is typically more than cast stretch film. Blown stretch film also has poor clarity, due to a high amount of crystallization during the manufacturing process. Because blown stretch film is cooled slower than cast stretch film there is more time for crystals to form in the film that reduces clarity. Blown stretch film is also noisy when being unwound. There is also a high amount of tension required to stretch the film onto the load. For smaller and lighter products, a higher tension is not required or recommended because it can crush the product and place unnecessary tension on the load.

Summary- Blown stretch film is ideal for heavier more expensive loads or loads with sharper edges. Blown stretch film offers excellent load capacity and load memory. Most products and loads do not require a more expensive higher load retention stretch film. Cast stretch film is commonly a more economical option and will work for the majority of loads. Our next post will focus on cast stretch film, the manufacturing process, advantages, and disadvantages.

Cast Stretch Film- Cast stretch film is made using the cast extrusion process. The cast extrusion process uses a horizontal die as opposed to the vertical die used in blown extrusion. The plastic melt is forced through the horizontal die, the slit in the die is flat so the film comes out in a flat film shape. The size of the slit in the die determines the thickness of the film.

After exiting the die, the film passes through chilled nip rollers. These rollers trim the film to a specified width while cooling the film. The film is then passed over more chilled rollers that cool the film. At the end of the rollers is a core that the film will be placed on. Once the film is placed onto the core, it is packaged into cases and prepared for shipping.

Advantages- Cast stretch film's primary advantage is cost. Generally, the cast extrusion process is cheaper and therefore cast stretch film is cheaper. Cast stretch film also offers great optics and clarity. The film is cooled faster in the cast extrusion process and fewer crystals are formed. The formation of crystals is what lessens clarity.

Cast stretch film also offers great tear resistance. This tear resistance helps to maintain load unionization in a variety of environments that tearing could be possible. Cast stretch film also offers a consistent thickness and cling. Due to the way blown stretch film is manufactured, it does not have as much consistency in thickness as cast stretch film.

Cast stretch film also offers a quiet unwind when being applied to loads. This makes cast stretch film preferred for many operations using stretch wrap machines.

Disadvantages- Cast stretch film does not have the same load retention qualities as blown stretch film. The memory after being stretched is not as good as blown stretch film, and puncture resistance is not as good either.

Summary- Cast stretch film is a great option for most any stretch film needs. The price helps to reduce costs and still have some advantages over blown stretch film. Blown stretch film should be considered for heavier loads or loads with sharp edges that may cause punctures.

Hand Stretch Film- Clear Hand stretch film is probably the most common stretch film people think of when they consider a stretch film. The majority of the time, hand stretch film comes on a three-inch round core. Another form of hand stretch film comes on one-inch extended core handles, but that will be discussed another post.

Hand stretch film normally comes in four roll cases at a length of 1500 feet per roll. These numbers can vary depending on the manufacturer, but four 1500' rolls are common. There are several different gauges and varieties of hand stretch film that people often overlook or are not aware of. First let's look at some advantages and disadvantages of hand stretch film, then let's look at a couple of varieties of hand stretch film.

Advantages- Hand stretch film offers many advantages to people or companies producing a low or mid-sized output of products or packages. Hand stretch film is easy to use directly out of the box and will stabilize, unitize, and secure a variety of loads. It is recommended that a stretch film dispenser be used when applying stretch film. The stretch film dispenser with a hand brake allows users to apply hand stretch film at different tensions to secure most any loads. Hand stretch film also uses no electrical utilities to apply the film. Hand stretch film comes in a variety of widths that allows users to stabilize a variety of load sizes using less film.

Disadvantages- Hand stretch film produces more waste and less consistent load tension than machine stretch film. Businesses handling a medium to high amount of production should consider a machine stretch film. Stretch wrap machines help to reduce waste by applying precise settings, as well as maintain a consistent load tension for all loads. Hand stretch film requires manpower to apply to loads. This manpower can often outweigh the electrical energy costs of a stretch wrap machine.

Hand Stretch Film Varieties- As mentioned above, there are several varieties of hand stretch film. Normally these varieties are offered in machine stretch film as well. We will not cover clear hand stretch film because most people are aware of this type of stretch film. We wanted to mention a couple of underrated hand stretch film varieties in this post and then do a separate post for specialty hand stretch films. Below are two overlooked hand stretch film varieties.

Pre-stretched Hand Stretch Film- Often overlooked, pre-stretched hand stretch film is just what the name says. A hand grade stretch film that has been pre-stretched then placed on a core. Some advantages include less tension when applied, lighter weight rolls, and less film used. Because the film is already stretched, not as much tension is needed to apply to the load. This pre-stretching also helps to reduce waste. Since the film is pre-stretched, the same length weighs less, which means less shipping costs when buying the film as well as a lighter roll to hold during application.

Micron Stretch Film- A newer hand stretch film that is made to be stronger and allow users to downgrade thickness and use less stretch film. Micron stretch film uses a new formula for producing a  Linear Low-Density Polyethylene (LLDPE) that makes the stretch film stronger, cheaper to produce, all with great clarity.

Machine Stretch Film- There are some machine rolls that come in smaller 3,000 ft. lengths, but most machine stretch film starts at 5,000 ft. rolls. These machine stretch film rolls are made to fit on a variety of stretch wrap machines. Two common types of stretch wrap machines are semi-automatic and fully automatic stretch wrap machines.

Machine stretch film normally comes in all of the stretch film varieties that have been pointed out earlier in this series. Two commonly used machine stretch film varieties are pre-stretched machine stretch film and opaque machine stretch film. Machine stretch film also comes in what is referred to as wide web machine stretch film rolls. Wide web stretch film rolls generally refer to machine stretch film rolls exceeding 20" in width.

Advantages- Any operation that is producing enough output will benefit from having a stretch wrap machine and using machine stretch film. Using machine stretch film will help reduce waste and increase efficiency. Machine stretch film will also help all loads to be consistently wrapped with the same tension. This helps to improve load security. Machine stretch film can also speed up output operations and allow workers to focus attention elsewhere.

Disadvantages- Not economical for smaller output operations. Rolls are considerably heavier than hand stretch film rolls. Shipping costs per roll is substantially higher than hand stretch film. Higher energy costs associated with powering the stretch wrap machines.

Uses- Machine stretch film is used in hundreds of different operations throughout the world. Everything from large fortune 100 companies, down to farmers and grocery stores. Large companies producing in excess of 30 loads per hour are more than likely using fully automatic stretch film machines to apply the stretch film. These fully automatic stretch film machines do not require an operator except to load the machine stretch film. Typically the load is transferred to and from the machine via conveyor belt. Machine stretch film rolls used in fully automatic machines can vary in length from 5,000 ft. all the way up to 10,000 ft.

Semi-automatic stretch film machines are more common and found all over the world in a variety of applications. They are great for lower output operations. Turntable stretch film machines are common when talking about semi-automatic machines. Turntable stretch wrap machines allow a forklift operator or jack operator to move the pallet load to and from the stretch wrap machine. The stretch film is fed on as the turntable rotates. Once the load is done the operator removes the load from the turntable.

Opaque Stretch Film- Opaque stretch film can offer a few benefits for users wrapping shipments. Our opaque stretch film is ideal for UVI protection. Great for protecting shipments from harmful rays from the sun. Opaque stretch film is also great to help conceal shipments, as well as color coding.

Color Tinted Stretch Film- The primary purpose of color tinted stretch film is to color code shipments. There is more variety in colors with the color tinted stretch film than there is in the opaque stretch film. Color tinted stretch film also offers some visibility through the film as opposed to opaque stretch film.

Static Dissipative Stretch Film- Static dissipative stretch film offers the same benefits as clear stretch film minus the static. Great for products that are flammable or sensitive to static electricity. Currently, we sell a static dissipative stretch film to several companies shipping electronic products. They do not want to take the chance of the static electricity damaging their products.

Airflow Pallet Wrap- Technically Airflow is considered a pallet wrap and not a stretch film. Airflow pallet wrap does offer some stretch but considerably less than stretch film. Airflow pallet wrap is made from a Linear Low-Density Polyethylene (LLDPE) that is strong and durable. The die-cut holes in the Airflow pallet wrap are ideal for providing ventilation to a variety of perishable products. Airflow pallet wrap is also great for cold storage because it does not have a flash freeze breaking point.

Wrapnet Pallet Wrap- Wrapnet pallet wrap is comparable to Airflow pallet wrap, because they both offer ventilation to pallet loads. Wrapnet pallet wrap differs from Airflow because it is made from a high density polyethylene (HDPE). This type of polyethylene gives Wrapnet pallet wrap a netting-like appearance that differs from Airflow. Wrapnet pallet wrap does offer some stretch, but not much compared to traditional stretch film. Wrapnet pallet wrap is a strong pallet wrap used by many farmers wrapping a variety of different produce.

Bundling stretch film- also referred to as banding stretch film, is a very versatile film that is ideal for a variety of different application and uses. Bundling stretch film generally refers to stretch film that is between 1 and 5 inches in width. Lengths and thicknesses come in different varieties. Bundling stretch film is offered in different colors and varieties focused on different applications. Rolls come on a 3" core or a 1' core extended handle for quick use and easy disposal. Below are some of the advantages, disadvantages, and uses.

Advantages- Light easy to handle rolls make application easy and less labor intensive. Often times bundling stretch film rolls come in many of the same varieties that stretch films come in. Rolls are small enough to pass through tight spots and continue unwinding.

Disadvantages- Rolls only come in sizes up to 5" wide, more revolutions required to wrap wider loads. Length of rolls is generally shorter than regular hand stretch film.

Uses- Bundling stretch film is commonly used in place of tape to bundle two or more objects together. It is an ideal stretch film for users who are trying to unitize smaller objects.