Automatic shrink wrap machines will detect a product, seal, and shrink without human operation. Automated machines have infeed and exit conveyors, which need to be loaded and unloaded as the line is in process. The term "automatic shrink wrap machine" is a general term that can refer to many different styles and functions of devices. Some of the more popular automatic shrink wrap machines include Auto L bar sealers, Auto Side Sealers, and Auto Bundlers.
See the descriptions of some automatic shrink wrap machines below.
Automatic L bar sealers use a photo eye or laser to detect products as they pass through the conveyor. After a product passes the sealing arm, the seals fully enclose the product in shrink film. After the seal, products continue down a conveyor into the shrink tunnel. The shrink tunnel has recirculating heat to shrink the film to the product evenly. Fully wrapped products exit the tunnel, and the film is conformed tightly to the product.
Automatic L Bar Sealers are fast because of the motion required to make a seal. The set L bar dimensions will make the same seal every time. Smaller products can run at 30 - 40 products per minute. Operators will be needed to load and unload conveyor belts during operation. Companies can wrap tens of thousands of products daily with the right automatic machine.
Product size and variations are essential to consider when purchasing an automatic L bar sealer. Different manufacturers include sizing options. For companies wrapping multiple different products per day, a touchscreen product sizing is ideal. Some automatic machines only have manual product sizing, which means that users have to turn adjustment wheels to fit the product manually. This additional time for sizing between each product can result in unnecessary downtime and lost production.
Type of Film
An L bar sealer should be used with a centerfold shrink film. A centerfold shrink film is folded lengthways and placed on a roll. A small pouch is created for products to slide into the film. The L sealer encloses the product in one movement. Stock centerfold shrink film is offered in thicknesses from 45 gauge to 100 gauge. Automatic machines do require more than an economy centerfold film to operate smoothly. The film should be made from polyolefin and recommended to be irradiated. Irradiated or crosslinked shrink film works better with hot knife sealers. The increased seal strength helps a hot knife sealer cleanly and efficiently make seals with no leftover residue.
The sealing blade is one of the most used items on an automatic L bar sealer. Most automatic machines use a hot knife sealer for product seals. Lower cost automatic machines use a wire to make seals as products pass through the conveyor. The use of a wire sealing blade for an automatic L bar sealer is not ideal. The wire sealing blade will wear out faster and will need replacement much more often than a hot knife sealing blade. The hot knife sealing blade is a thin piece of metal that is heated to the desired temperature to make seals over and over again. With proper cleaning, a hot knife sealing blade will last for years.
Automatic Side Seal Machine
An automatic side seal machine uses a photo eye or laser to detect products as they pass through on the conveyor. After products pass, a single-sealing arm running perpendicular to the film closes behind the product. As the product continues down the conveyor, a side sealing wheel makes the final seal to enclose the product. The advantage of the side seal machine comes from the ability to wrap longer products. The width of the product is limited to the verticle sealing bar, but the length can be as long as needed. A perfect option for shrink wrapping moulding, pipes, wood, and other elongated items.
Auto side seal machines are slightly slower than auto L bar sealers. Most side seal machines max out at 30 products per minute. The longer products used in a side sealing machine takes more time to seal and move down the conveyor line. More extended infeed and exit conveyors are recommended to fit products are they move through the line. An operator at the entrance and exit are required to keep the production line running continuously.
An automatic side seal machine is made to wrap larger products. The side sealing wheel requires excess film to create a consistent seal. Due to the required excess film, small products do not look as clean after heat is applied. Any products less than 4 inches by 4 inches will have more excess film used than an automatic L bar sealer. Elongated products are what a side sealing machine performs the best with. The side sealing wheel can make a continuous seal down the length of the product creating a large bag to enclose the product being wrapped. In testing, with a long shrink tunnel, we have wrapped products over ten feet long!
Type of Film
Side seal machines are made to be used with polyolefin centerfold shrink film. The side sealing wheel seals one of the open ends, and the vertical sealing bar makes the other two seals. Wider centerfold film is recommended with a side seal machine. We recommend anyone adding an extra two inches to the film width needed with other machines. The additional inch or two inches of width offers more room for the side sealing wheel to make a clean seal. A crosslinked polyolefin shrink film works great with a side sealing machine. The side sealing wheel makes stronger seals with a crosslinked film if available to run.
A sidesealing machine has two different sealing blades. The vertical sealing bar is usually a hot knife sealing blade. Capable of lasting years with proper cleaning. The sealing bar opens and closes as a photo-eye detects passing products. Opposite the hot knife is a sealing pad with Teflon tape. Over time, the sealing pad and Teflon tape will need to be replaced. For the side seal, a metal sealing wheel is used. The sealing wheel temperature can be set as desired. Keeping film and residue off the sealing wheel will enable it to last for years.
Automatic Shrink Bundling Machine
Automatic shrink bundling machines are different than the other two automatic machines mentioned above. An automatic bundling machine is built to wrap heavy products with thick film. One of the most recognized products wrapped with a shrink bundling machine are cases of water bottles. The bundling film is applied around the bottles and shrunk down after a seal is made. The finished packaging has two open ends on each side. Because bundling machines use thicker film, higher temperatures are needed to seal and shrink the film being used.
The speed of an auto bundling machine depends on the size of the machine. Large bundlers have longer tunnels and conveyor lines. They can package products faster, increasing conveyor speeds and shrinking film as it moves through the tunnel. Smaller combo automatic bundling machines can not package products as quickly. Most smaller bundling machines less than fifteen feet in length average of 15 to 20 products per minute. The lower end 15 ppm would be with a thicker film that requires longer seal and shrink times.
The primary purpose of a shrink bundling machine is to wrap heavier products. Standard products packaged with a shrink bundling machine include firewood, canned goods, cases of water, metal products, tool cases, and more. It is important to remember that the two ends of the product will be open after the film has been sealed and shrunk. The open ends are referred to as "bullseyes." A wide 20" sealing bar is capable of packaging smaller products if needed. If wrapping 12 OZ bottles, users can wrap 6, 12, and 18 packs.
Type of Film
Bundling machines can only run a single wound shrink film. Single wound shrink film comes off the roll flat, not centerfold. Polyethylene bundling film is the most common material used. Thicknesses range between 2 to 6 mils thick. It is essential to choose the correct width of the film selected. The width will determine the size of the "bullseyes" on the side of the packaged product. Too small of film will cause large bullseyes and packages easily tearing.
Due to the thickness of the film being wrapped, a thick sealing blade is needed. Fully automatic shrink bundlers use industrial-strength hot knives to make seals on thick and heavy film. The verticle sealing arm closes as products pass the photo-eye. The single seal is all that is needed for a shrink bundling package. After the seal is made, products are transported via conveyor through the bundling tunnel.