What's the difference and why is cast film (in our opinion) better?
The numbers don’t lie. Increasingly, business owners are shifting away from traditional blown film packaging and choosing cast film instead. With improved efficiency and sustainability standards, cast film is used by around 70-80% of the industry globally.
Yes, the popularity of cast film may be enough to convince you to make the switch. However it’s worth understanding how these films are made too. In this way you can make an informed decision on which way to go…
Blown Film. This is the traditional way of producing film and takes its name from the process used to create it. Heated resin is blown through a circular die, and a thick layer of extruded film emerges as a large bubble. The bubble can be many feet tall – and it is this height that allows the film to gradually cool before rollers collapse the bubble and flatten the material for shaping onto rolls.
The very nature of blown film makes it a pre-stretched product, and the thickness of blown film is adjustable dependent on the diameter of the tube from which it comes.
Cast Film. Cast film is created by feeding a sheet of heated resin through a flat die. The molten material emerges from the die and out onto larger chilling rollers which cool and solidify the material. It is then ready for trimming and rolling.
Cast film is minimally pre-stretched compared with blown film giving it improved depth of drawing for thermoforming operations. The cooling process can be used to produce different characteristics in the final product. Cast film can be thinned by winding the film out of the roller faster than it is extruded.
There are likely to be many factors to consider when choosing which film to use. These may include the environmental conditions (is it cold or frozen?) storage and transportation processes, and what level of pre-stretch is needed. Here is a quick breakdown of the pros and cons of each type of film.
Blown Film
Has a higher resistance to puncture; preferred for wrapping sharp-edged products and heavy loads such as masonry and construction materials
Film offers less clarity due to crystallisation which occurs during manufacture
Has a high level of cling
Cast Film
Comes off the roll easily and is quieter than blown film
Often used for lighter products, and loads stacked on pallets
Very clear product making it easy to scan barcodes through the film
Requires less force to stretch
High tear resistance
How much energy is used to make a plastic bag?
The plastic carry bag is an established part of Australian shopping. The nation consumes approximately 6.9 billion plastic bags, or 36,850 tonnes of plastic, each year - this equates to just under one bag per person per day. About 53% of plastic bags are distributed from supermarkets, while 47% come from other retail outlets such as fast food shops, liquor stores, and general merchandising. One of the main methods of managing the use and disposal of plastic bags is the voluntary National Code of Practice for the Management of Plastic Retail Carry Bags (Australian Retailers Association 2002).
Plastic bags are popular with consumers and retailers because they are a functional, lightweight, strong, cheap, and hygienic way of transporting food and goods. Additionally, the manufacture of plastic bags uses little energy. However, research has shown that energy use and greenhouse gas emissions can be reduced by switching from the commonly used bags to larger, reusable bags, by expanding the Code, and introducing a levy. These options are discussed briefly below.
The two main types of plastic bags used in Australia are the 'singlet' bag made of high density polyethylene (HDPE) and the 'boutique' bag made of low density polyethylene (LDPE). The HDPE bags are mainly used in supermarkets and take-away food shops, whereas the LDPE are commonly used in department and fashion stores. In 2001-02, 66% (or four billion) of all HDPE bags and 25% (or 225 million) of all LDPE bags used in Australia were imported.
Around 0.48 megajoules (MJ) of energy is consumed to make one HDPE singlet bag including the energy content of the bag (the embodied energy). Another way of considering this is that the energy consumed by driving a car one kilometre is the equivalent of manufacturing 8.7 plastic bags (Nolan-ITU 2002).
By comparison, it is estimated that the making of a plastic bag uses up to 70% less energy and produces around half the greenhouse gas emissions than a paper bag (National Plastic Shopping Bags Working Group 2002). However, the amount of energy used and greenhouse gases emitted in the manufacture of plastic bags does not compare favourably to other alternatives, as shown in table S17.1. Over one year, using woven HDPE bags consumes 9% of the energy and produces 10% of the greenhouse gas emissions compared with using standard HDPE bags (Nolan-ITU 2002).
Further, modelling has shown that significant energy savings are possible with the introduction of a plastic bag levy. Under the current Code, plastic bag manufacturing uses 2,540 gigajoules (GJ) of energy per year. If the Code is expanded and a legislated levy of, say, 15 cents per bag is introduced, energy use could be cut by 54.9% (to 1,160 GJ a year). If a 25 cent levy was introduced, energy use could be reduced by over 60% (to 940 GJ per year; Nolan-ITU 2002).
Woven Vs Non-Woven Bags – What Is The Difference?
One of the most frequent questions we get asked by our clients is: what is the main difference between a woven bag vs. a non-woven bag? Our blog explains technical and design features to help you design and manufacture unique branded products. Now that we have launched our new website for Patented Reflective Bags, it is important to understand not only the benefits of reflective piping but also the raw materials involved.
This case study looks at the main differences between a woven bag and a non-woven bag. Both materials make great imprinted tote bags, but they are distinctly different. Each type has unique benefits and characteristics.
Woven bags are made from fabric that has been woven to give the fabric strength. The process of weaving involves joining individual threads together to make a single piece of material. Doing this over and over again creates one large piece of cloth. The cloth is then used to manufacture tote bags in a number of different styles and shapes.
Benefits of using woven fabrics:
Woven cloth is flexible
It is able to retain its shape well.
Woven fabrics are strong, therefore, bags can be reused multiple times.
A woven bag can be cleaned in a washing machine.
Can be designed in a laminated or matte finish. A non-laminated woven bag is not recommended as they will have a cheap look.
How a Printing Press Works
A printing press is a complex piece of high-precision industrial equipment that is designed to produce printed material at a high rate of speed and low cost per page. Printing presses are commercially available which use several different types of printing technologies, but the most common type is called offset lithography. These presses are commonly designed in either sheet-fed configurations, which print on individual sheets of paper or other material, or web-fed configurations, which print on long webs of paper or other material, supplied on large reels. A so-called 'full size' sheet fed offset press prints on sheets that are about 700 mm x 1000 mm in size (about 28 inches x 40 inches). "Half size" and "quarter size" offset presses are also common, and these machines print on sheets which are one-half or one-quarter as large.
An offset printing press has a separate printing unit, or tower, for each color of ink. Some presses have as many as 12 towers, first printing 6 colors on one side of the sheet, then flipping the sheet over, in a device called a perfector, and finally printing 6 colors on the reverse of the sheet. Normally black plus the three subtractive primary colors (cyan, magenta, and yellow) are the 4 main colors printed. Other inks added to these four main colors are typically spot colors, which are highly saturated colors outside the color gamut which can be achieved with the subtractive primaries - these are commonly employed as logo colors, or they may be colors which are being used for some striking artistic effect.
How It Works: Inside The Machine That Separates Your Recyclables
The most annoying aspect of recycling—and one of the biggest hurdles to its widespread adoption—is having to separate paper, glass, and plastic before they hit the curb. New recycling machines are changing that. With single-stream recycling, recyclables go into one bin, which a truck delivers to a materials-recovery facility, such as Willimantic Waste Paper in Willimantic, Connecticut. There, a largely automated system of conveyor belts, screens, magnets, and lasers separates materials so that they can be sold to metal and plastic recyclers and paper mills.
Of the 570 recycling facilities in the U.S., 240 now have single-stream operations, according to Eileen Berenyi, of the solid-waste research-and-consulting firm Governmental Advisory Associates. While the system isn’t perfect—its high-speed operation can lead to contamination from broken glass—the simplicity of it means households actually recycle more. “If people want a higher recycling rate, it has to be convenient,” says Chaz Miller, of the National Solid Wastes Management Association. “And I think the technology is only going to improve.”
1) Tipping floor
Dump trucks deliver mixed recyclables to the facility and pile them on the floor. The driver checks to make sure no oversize objects, such as a car engine, are in the mix.
2) Drum feeder
A mechanical claw grabs a handful of material from the tipping floor and drops it into a spinning drum, which evenly distributes the recyclables onto a conveyor belt.
3) Initial sorters
Workers extract plastic bags, coat hangers, and other items that might jam up the line, as well as anything that won’t fit through the sorter.
4) Large star screens
A series of offset star-shaped discs called star screens—originally invented by the Dutch in the 1950s for sorting tulip bulbs—lift out corrugated cardboard. Smaller items fall through the screens and continue down the conveyor belt.
5) Second sorters
As the material travels away from the star screens, human workers positioned along the line remove smaller contaminants. “This is where we pull out people’s wallets,” says John DeVivo, a co-owner of Willimantic Waste Paper.
6) Medium star screens
Three smaller star screens lift out different grades of paper, which makes up two thirds of recycled material at Willimantic Waste Paper. Plastic, glass, and aluminum fall through the screens and roll back down onto the main belt.
