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I need to estimate the static spread force (Newton) that a plastic wrap wound around a given square frame (1 sq meter) can sustain.

The stretch film has a given thickness (eg 17 microns ~ 63 gauge) and I have found a table that gives a weight that a given thickness can sustain. For example 63 gauge plastic wrap is said to fit loads up to 2200 lbs.

But I don't know in which direction the 2200 lbs are measured. Because plastic stretch film is wrapped AROUND the load not below since is is carried on a wooden pallet. So the plastic film does not hold the weight of the load, right ?

Moreover I have 17 micron film and I can pierce it with my finger or tear it and I know I am not as strong as 2200 lbs.

Yet a presentation shows that kitchen cling wrap can only hold between 5 and 15 pounds which is way different from the previous 2200 lbs but matches more what I would expect from the plastic stretch film I know.

Consequently I need to compute it myself but I don't know how. I think it has to do with flexural strength but I am not so sure.

Finally could someone bring me on the right tracks so that I can handle this problem. Also could somebody explain what these 2200 lbs correspond to ?

Many thanks in advance

ChewingGumExpert
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  • How is the load to be applied? incrementally or dropped from 1 metre? – Solar Mike Aug 16 '22 at 17:32
  • You might find some useful information on shrink wrap film and machines. These will apply force by tension in the wrap direction. You'll need to convert your measures to force per unit width of film. Go metric and use newtons. It saves a lot of confusion. – Transistor Aug 16 '22 at 17:42
  • @SolarMike load is uniform (water) and static. – ChewingGumExpert Aug 16 '22 at 17:57
  • @Transistor I am using stretch film. Do you mean that the 2200 lbs correspond to the force in the wrap direction (aka machine direction) ? That's huge isn't it, could I break it ? And thanks for this piece of advice regarding SI units. Sure I won't try to do the math with gauge lbs psi :D ! – ChewingGumExpert Aug 16 '22 at 18:17
  • Apologies; I said shrink-wrap. I should have said stretch-wrap. The wrappers generally do multiple wraps so I suspect that you could just multiply by the number of layers. I had a quick look but I couldn't find a specification for recommended maximum tension although all the wrappers have adjustable tension settings. – Transistor Aug 16 '22 at 18:23
  • the 2200 lb is the total weight of the item that is being wrapped ... it is not how much weight the wrap will support ... it is more of a rule of thumb ... the stretch wrap is mainly intended to contain several separate items, such as boxes – jsotola Aug 16 '22 at 18:53
  • @Transistor Right, in the above link they recommend to wrap at least 5 times at the bottom. You mean if a layer can hold 10 lbs then 10 layers could hold 100 lbs, right ? I will take this assumption as a starting point. – ChewingGumXpert Aug 16 '22 at 19:49
  • @jsotola Rule of thumb, ok got it, thank you ! – ChewingGumXpert Aug 16 '22 at 19:50
  • Keep track of this question: https://engineering.stackexchange.com/q/52158/10902 – Solar Mike Aug 16 '22 at 21:32

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