Shrink wrap involves two things. The first is to wrap the pack either completely or partly. The second is to apply heat to the wrap film.
Shrink Wrap Application Types:
Transit is affordable. This is because the material used is polyethylene. It may not have tray support. This type of packing is usually done with cans or bottles. There is a sleeve or bundle sealer together with a shrink wrap tunnel. If necessary, the tunnel can be modified by closing it and sealing off the excess film. The sealing could be done by human effort, semi or fully automatic sealers. The speed of sealing is about 200 packs per minute. Single packs are wrapped using this method of application. Things like radiators, doors and bolts are wrapped in this way.
In this type of shrink wrapping, the sleeves are also used because the products need it. In all other ways, the method is exactly as the transit method. Things like gifts and wall paper rolls are wrapped this way. Pieces of the product being wrapped can be fitted into the sleeves and sealed.
In all cases, the sealer needs to make a flat 2 dimensional bag wrap around the product. Then the bag and the product are passed through a shrink tunnel. The product is put between two layers of film and then placed in the sealer. Now the process of sealing is done and the pack is kept on the conveyor. The seal head and pack support is automated. Finally, the sealer head is clamped down with a solenoid or a pneumatic ram.
The Difference between Manual Wrapping and Automatic Shrink Wrapping
·A manual machine can wrap ten packs per minute while an automatic machine can wrap twenty packs in the same amount of time.
·A manual machine costs about 2000 pounds while an automatic one costs about 20,000 pounds.
Combined seal and shrink wrap machines are preferred to manual sealer and tunnel. The sealer head has a plastic covering so that the heat is stored within the unit for a combined seal and shrink to take place simultaneously.
Both side seal and flow shrink wrap machines can do 100 packs per minute. Cross seals move with the pack, allowing side seal or overlap seal to be done.
Most of the time flat film is used to shrink wrap products, but sometimes folded film is also used.