For small to mid-sized food manufacturers looking to place shrink wrap, film, bands or sleeves on products to create tamper evident seals, preserve freshness or even band products together in a multipack, selecting the right equipment comes down to a series of critical decisions.
Chief among these are selecting the method and design of heat application, the sizes and types of consumables and even the size of the shrink tunnel chamber opening for oversized or unusually shaped products that do not fit neatly into off-the-shelf models. In other words, shrink tunnels ideally should fit the application for which it is intended. Although many off-the-shelf models may do the job, selecting equipment that can be lightly customized by the manufacturer--often at no additional cost--can greatly reduce long-term operational and maintenance costs.
For Stan Stubblefield, president of De Casa Fine Foods--a Eugene, OR-based producer of organic salsas, bean dips and hummus--paying attention to these types of details had a dramatic impact on his company’s bottom line. The company applies a tamper-evident shrink band to its products.
“We achieved ROI on our shrink tunnel in less than 24 months when we started out, and continue to earn a full return on our investment in it every 12 months at our current volume,” says Stubblefield. “It’s helped us to grow our business, and since 2010 we’ve averaged over 15 percent annual growth.”
The Shrinking Craze
Almost everyone at this point is aware of products in shrink packaging. The concept is straightforward--a film, bag, band or sleeve, is placed over the product by hand or using automated equipment. Heat is then applied and the unique material tightens and shrinks to a snug, form-fitting outer layer.
Perhaps the most easily recognized application for shrink wrap is for gift baskets. However, shrink bands and sleeves are now increasingly being utilized to provide tamper-evident seals to secure lids, caps and nozzles for everything from bottled water to yellow mustard and even ice cream. They are similarly used to secure containers of prepared foods such as fresh cut fruits and vegetables, hummus, prepared salads, nuts, cookies and chocolates.
Shrink wrap, film or bags are another popular type of packaging for products like frozen pizzas and baked goods to fresh cut quarters of watermelon or cantaloupe. Shrink bands are also being used to meet the requirements of large retail outlets like Costco that sell in bulk, binding together two identical or similarly[ed1] sized products as multipacks.
Heat Application: Infrared vs. Heated Air
Although shrink materials will respond to any type of heat--even a blow dryer--for most small to mid-size food processors packaging in any volume an automated shrink tunnel is required. Of these, the predominant method of heat application typically falls into one of two categories: infrared or re-circulated, heated air.
Infrared technology, the choice of many offshore manufacturers, has several limitations. Most off-the-shelf infrared units have a limited tunnel opening size and can only accommodate product up to four to six inches high because infrared tubes have a limited effective range of heat radiation and must be close to the product.
“Shrink tunnels with six-inch high openings would be too short to accommodate our product, if we stack it for retail combo packs or bulk retail sales,” says Stubblefield, adding that the company is planning to do just that in the near future to create a stacked salsa and bean dip retail combo pack bound in a shrink sleeve.
Generating enough heat to shrink wrap food product with infrared tubes can also be costly since a relatively large amount of its energy is emitted as light, not heat. The infrared tube fixtures are comparatively costly to repair and replace. In addition, since infrared tubes have fixed positions, directing the heat efficiently is difficult, if not impossible.
“With shrink tunnels using infrared, I’d be concerned that heating tubes would require frequent replacement or wouldn’t heat around the product evenly,” says Stubblefield.
The alternative option is a model designed to use heated, re-circulated air, such as the equipment De Casa Fine Foods purchased from ATW Manufacturing, a provider of high-speed shrink tunnels, L-sealers, and packaging supplies.
Shrink tunnels using such heated, re-circulated, adjustably ducted air enables more efficient customizable options in terms of tunnel height, width and heat location. Such equipment, it turns out, is also easier to control than those using fixed-in-place infrared tubes. Some shrink tunnels can, in fact, be designed to apply heat directly where it is needed, such as the nozzle or lid of a bottle, as opposed to the entire product, to decrease energy costs.
“We are not attempting to ‘push’ heat onto a product as hard as we can, but specifically apply the heat where it’s required to optimize efficiency,” explains Tom Drew, president of ATW Manufacturing. “By directing the heat only where it is needed, food processors can save 20 percent or more on energy costs while improving production output.”
According to Drew, because equipment from ATW is dual side ducted within fully insulated heat tunnel chambers, most of the airflow can be efficiently ducted down the side and blown perpendicular to the conveyor belt on both sides, usually targeting container lids.
When the application is for low profile container lids such as dips or spreads, the heated airflow is usually focused an inch or two above the conveyor belt for maximum heat transfer efficiency. The side-ducted airflows can also be user-adjusted to accommodate taller containers, such as vinegar bottles requiring a tamper evident shrink band on the cap.
When even heat shrinking across the entire container is required, the heated airflow can be blown straight down from the top of the tunnel chamber to encompass an entire container from top to bottom.
For food processors with larger or unusually shaped products, ATW manufactures shrink tunnels with chamber openings up to 20-inches high by 15-inches wide. This enables shrink wrapping of large gift baskets, tall items such as standing wine bottles, as well as products to run through the machine side-by-side for greater production speed.
“We often run two products, side-by-side through our shrink tunnel for faster output, and could run three products through side by side,” says De Casa Fine Foods’ Stubblefield. “Our shrink tunnel’s horizontal and vertical clearance helps us to optimize our production and product packaging.”
This type of equipment is also less costly to maintain using low-cost repair kits. The combination of a low initial purchase price, low maintenance costs, and optimized production efficiencies makes for a quick ROI.
“In the 12 years, we’ve used our ATW shrink tunnel, after about three million products run through, we’ve only had to replace the thermostat and a toggle switch, which cost about $100 total,” says Stubblefield. “It would be very helpful to any food start-up that needs inexpensive equipment that can ramp up with them as they expand their volume.”
To further speed production, food processors using wrap, film, bags, or sleeves have the option of automating the process using L-sealers that loosely wrap and seal the product before it enters the shrink tunnel. An L-sealer can seal up to 22 items per minute, with up to a 14”x30” sealing area.
Del Williams is a technical writer based in Torrance, California. Learn more about ATW Manufacturing at ATWMfg.com.