Finished Shrink Wrap Problems: Hot Spots Or Holes
Effect: They are termed hot spots but are really holes in the shrink film which look as if a lighter has singed the finished film. In essence the shrink film has overheated in a particular area.
The path of least resistance is your problem. While shrink film is made to be equal across all parts, every structure or material is either made to have a weak point or simply has one. Therefore it's not one particular area inside a tunnel causing the problem or a defective part of the shrink wrap.
What is a Hot Spot not? Unfortunately Michael Barrymore lovers, in this instance a hot spot is always a hot spot but they can be prevented from occurring. Simply by taking the following actions and running tests before running a continuous packing line.
The shrink wrap process is evidently too hot for the film to handle. If you have previously programmed settings and the product you are now wrapping is larger, you may need to simply adjust heat temperatures.
- Allocation of overall heat to a shrink film is not only controlled by temperature but by motion also. Consider whether the conveyor is moving too slowly and should perhaps be speeded up.
- There may be a problem with heat not being exhausted and not enough air evacuation holes. Why not trial the use of shrink film which has micro perf venting and holes in the film to lessen the effect of hot air build up within.
Much like Fish Eyes and Dog Ear's, the cause of hot spots could be that the heat vacuum and air velocity within is too high also. While it is rare, the type of shrink film you use may also not be compatible with the shrink wrap machine you are using. And if manually applying the shrink bag to the product, gauge distance better and ensure the heat gun is not too close.