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What is an Automatic Shrink Wrap Machine?

Automatic shrink wrap machines reduce product handling and increase production times. An auto shrink wrap machine does not require an operator to engage the sealing bar or transport products into the heat tunnel. Products are placed onto an infeed conveyor and exit the auto machine packaged in shrink wrap.

Companies can differ on production level needs. Small start-ups or new product roll-outs may require a manual shrink-wrap system. These will have everything needed to begin. Over time and with enough volume, manual machines can eat up time and lack consistency. Once products per day exceed 1,000 packages, a semi-auto shrink wrap machine can be a vast improvement over manual wrapping. Though the operator needs to close the sealing bar, and with some machines, move the product into the shrink tunnel, it is much better than using a heat gun. The tunnel maintains a consistent temperature for an even shrink every time. Some semi-auto shrink wrappers can package 3500-5000 products daily within an eight-hour shift.

Running multiple shifts requiring the need to heat shrink package thousands of products each shift, an automatic shrink wrap machine is a no-brainer. Made for higher production levels and faster packaging, an automatic shrink wrap machine will reduce man-hours while increasing speeds. Below we list some of the essential components of an automatic shrink-wrap machine. There are many add-ons and options based on product requirements and needs that may not be listed. Instead, this is a basic list to show anyone interested in purchasing an auto machine what may be required.

Automatic Shrink Wrap Machine Components

The automatic shrink wrap sealer is the line's centerpiece but is often run with other components to accomplish professional shrink packaging quickly. There will always be additional add-ons available with each manufacturer, be sure to find out if any additional features will benefit your packaging process.

Infeed Conveyor

Infeed Conveyor

The auto sealer will have an infeed conveyor sending products into the sealing area. In addition to the small conveyor in the machine, an external infeed conveyor is highly recommended. The additional conveyor is more accessible for operators to load and provides better product spacing than the small internal conveyor belt.

For longer products, a bigger external infeed conveyor will be required. An automatic side-seal machine can seal long products with a continuous feed but will require the right conveyors supporting the products as they move through the machine. For other stacked products or smaller items, specialty infeed conveyors may be required to achieve a professional look. There are many conveyor options, be sure to inquire if any specialty conveyors would assist your products.

Automatic Shrink Wrap Sealer

Automatic L Bar Sealer

The automatic shrink wrap sealer features photo eyes or sensors to see products as they pass. When the product moves past the sealing bar, the seal comes down to fully enclose the item within the shrink wrap. Some auto sealers require manual adjustments for product sizing, while others have digital sizing adjustments that can be made from the control panel screen. The seal configuration will depend on the material used and the product size. Popular auto sealers have an L bar sealer configuration, crossbar or I bar sealer configuration or a continuous side seal wheel with a cross sealing bar. Below is a brief explanation of each.

Automatic L Bar Sealer – Auto L Bar sealers are designed to run with centerfold shrink film. The L sealing configuration heat seals two sides of the material when the bar closes. The L sealer is limited by the product length that can be sealed. It is the perfect size for many retail and e-commerce products.

The consistent vertical motion of the L bar sealer ensures a reliable seal and shrink every time. Most auto L bar sealers have a hot knife sealer. The hot knife is a temperature-controlled sealing area that lasts longer than traditional wire sealers. Each side of the sealing bar can be set to a specific temperature for accurate seals every time. For smaller products, a ‘closing conveyor’ may be required to ensure products do not fall between any gaps between conveyors.

Automatic Side Seal Machine – Side seal machines have a single sealing bar across the width of the shrink film and feature a sealing wheel to seal the film's length. Auto-side sealing machines can wrap standard-sized products but excel at wrapping longer products. The continuous side wheel can wrap products several feet long. When the end of the product crosses the photo eye, the cross seal bar comes down to cut and enclose the oversized item.

The crossbar for a side sealing machine is often a hot knife sealer. Similar to the auto L bar sealer, a set temperature can be maintained to promote proper seals time and again. The sealing wheel and crossbar must be cleaned as part of regular maintenance if the machine is run often.

Automatic Shrink Bundler – Auto shrink bundlers are for packaging heavier products. The finished package can easily be identified by the holes or bullseyes on each side. The auto shrink bundler only uses a cross-sealing bar to seal a single-wound bundling film which is discussed in more detail below.

Because the materials and products used with this machine are heavy-duty, bundlers are larger machines that require more power and space. The heat tunnels for many shrink bundlers are at least sixty inches long. Cooling fans can also be found outside the tunnel to help materials cool after running through the heat.

Automatic Shrink Wrap Tunnel

Large Shrink Tunnel

Heat tunnels are available in a vast array of sizes and lengths. In addition to the sizing options, there are different heating options. The most commonly used heating sources are recirculating air, infrared heat, and steam. Depending on the product type and requirements, either tunnel mentioned can be used with the proper auto sealer. Below is a short description of each and what they can be used for.

Recirculating Shrink Tunnel – Heaters turn on when signaled by the thermostat, and fans circulate heat throughout the enclosed tunnel. The most common tunnels used with auto L bar sealers and side seal machines.

Infrared Shrink Tunnel – Heated lamps inside the tunnel provide targeted heat. Great options for shrink neck banding, shrink sleeves, and shrink labels. For fully enclosing and shrink wrapping products, infrared tunnels can leave hot spots and can struggle to obtain an even shrink rate.

Steam Shrink Tunnel – With the use of water and a steam generator, stainless steel steam tunnels are used for shrink sleeves around bottles and rigid containers. The sleeves are more affordable and look better than printing on rigid containers.

When coupled with an automatic shrink wrap sealer, the tunnel’s conveyor transports sealed, loosely fitting film through the heated tunnel chamber at a set speed. The consistent movement and heat will ensure products look perfect time and again.

Exit Conveyor

Exit Conveyor

For use with automatic shrink wrapping, an exit conveyor is placed at the end of the shrink tunnel. Finished packages will be warm and possibly even hot after exiting the heat tunnel. Many people choose gravity conveyors to move finished products from the heat tunnel.

If the auto machine is part of a more extensive line, powered exit conveyors may be necessary after products leave the heat tunnel. Powered conveyors can transport from one area to another for additional packaging or order fulfillment requirements.

Shrink Film

Shrink Film

We have discussed three automatic shrink wrap machines so far and described each one. It is also essential to highlight the type of shrink film they use. The automatic L bar sealer and side seal machine use the same type of film, but the shrink bundler uses a different material. Below is a description of each shrink material and why they are used with each machine.

Crosslinked Shrink Film – Automatic L bar and side seal machines with a hot knife sealer work when used with a crosslinked polyolefin shrink film. A crosslinked shrink film has interwoven, crosslinked polymers to make the material stronger and capable of more seal strength. The crosslinked film found on auto shrink machines is centerfolded, meaning one side is folded coming off the roll. Crosslinked polyolefin shrink film is FDA-approved for direct food contact; for more information view our previous blog post detailing what is crosslinked polyolefin shrink film.

Bundling Shrink Film – Different from centerfold shrink film, bundling shrink film comes off the roll flat. It is considered a single-wound shrink film. The auto shrink bundling machine uses two bundling rolls made from polyethylene shrink film to cover packages. Most often cases of bottles or cans are packaged with a bundling machine and film.

Polyethylene shrink bundling film is heavy-duty, and a two-mil thickness is often the thinnest available. Thicker materials require higher temperatures for shrinking. This is the reason automatic shrink bundlers are larger and heavier-duty machines. Once packaged items leave the heat tunnel, cooling fans may be needed to help the shrink material cool. As polyethylene bundling film cools, it continues to shrink.


Whether replacing a machine or moving up to an automatic shrink wrap machine from semi-auto, it is crucial to know the components that are vital to the automated process. With the right equipment and materials, companies can expect to package tens of thousands of products daily with an automatic shrink wrap machine. The best way to confirm products are the right fit for an automatic shrink wrap machine is with testing. For more information about testing your products in-house, call 1-800-441-5090 and speak with one of our associates today.


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