Re-Thinking Non-Powered Pre-stretch Stretch Wrappers

For years people have argued that powered pre-stretch stretch wrappers are a must.  WHY?

It’s simple really, because that is what we were all trained on years ago to sell a higher priced machine.  We also told everyone that 80 gauge film was a down gauged product (of course back then it was).
Now, just because you would run a 70 or 80 gauge stretch film on a powered pre-stretch machine (and in many cases a much lower gauge) does not mean that what is good for the goose (powered pre-stretch machine) is good for the gander (non-powered pre-stretch machine/core brake machine).
Allow me to expand….First we must look at the machine types and determine how they work to get a basic understanding of the fundamentals.  To make it easy for me we will use a simple graphic of a bicycle.  As you can see below, each time you pedal with your legs, the sprocket labelled A will go one complete turn.  Because of the differential in the size of the sprockets between sprocket A and sprocket B, B will turn perhaps 2 times around.
Now lets apply these basics to a stretch wrap machine.

Powered Pre-Stretch:

  1. Our Legs are replaced by an electric motor
  2. So every time the motor turns sprocket A one time, sprocket B turns twice.
  3. NOW if each sprocket was attached to a roller that carried film, and they are the same size, for every rotation of sprocket A, B would turn twice which would create a stretch between the rollers of 100%.
  4. The force it requires to stretch the film is absorbed by the motor. Therefore with a POWERED PRE-STRETCH machine you can lay the film on loose like a dust cover, or so tight it either breaks the film or crushes the product being wrapped.

NON-Powered Pre-Stretch

  1. The film is pulled through the rollers and attached to the pallet to be wrapped.
  2. So every time the motor turns sprocket A one time, sprocket B turns twice
  3. In the above sprocket example, you will still get 100% stretch but not the pallet will rotate pulling the film out f the machine.
  4. The force it requires to stretch the film is absorbed by the PALLET OF PRODUCT.  Therefore with a NON-POWERED PRE-STRETCH machine you can only wrap pallets in film that have the stability to stay in-tact while forces are applied equal to what it takes to stretch the film.
  5. EXCEPTION TO THE RULE – Core brake technology does not use gears and sprockets to change the stretch, they incorporate a braking method on the roll carriage that will create resistance.  Changes to the brake tension will create changes in stretch.

DOES THAT MAKE SENSE?

Stated in a more simple manner, when utilizing a NON-Powered Pre-stretch system, all of the force is absorbed by the pallet of product.  Regardless of it is a geared system or a braking system, the force is applied to the load.
NOW LETS TALK THE OTHER PART OF THE EQUATION – FILM!
As you can imagine, if I have an 80 gauge film and a 45 gauge film, they will take different force to stretch them both the same amount.  As wise man has taught me over the years “There is no replacement for mass”, so it is most likely the 80 gauge will require more force to stretch 200% than a 45 gauge.  So what does that mean to you, the consumer?  You will get less containment with a 45 gauge film than an 80 gauge because it takes less force to stretch it to its maximum point of elongation, or it will break with less force than the 80 gauge.

NOW LET’S TIE IT ALL TOGETHER:

Because of what we just discussed regarding film and the types of stretch machines available, what is right for your Non-Powered Pre-Stretch machine?  Lets take the following items into consideration:

  1. What is the value of the load being wrapped?
  2. How far is it travelling?
  3. How is it being shipped?
  4. What is the weight of the pallet load being wrapped?
Now that you answered those questions, consider that if I wrap on a Powered Pre-stretch machine at 250%  (which is stretching the film from 10″ to 35″ before the film leaves the machine) I may start with an 80 gauge but it is a 30 gauge possibly as it is applied to the pallet (as the film thins while being stretched).With a Non-Powered Pre-Stretch it may only stretch it using a core brake (which will not allow for more force than the pallet can withstand without the film pulling the pallet load apart) that 80 gauge may only allow for me to stretch 30% (or 10″ to 13″).  This film would be applied on the pallet at a 70 gauge (as the film will thin as it stretches).

MY SOLUTION: Apply the 45 gauge so it stretches 125% (again, determined by the force you can apply without pulling your pallet load apart). All of the force is applied to the load giving you excellent containment force and as the film is thinned and applied it is probably in the area of the same thickness of the Powered Pre-Stretch applied film.

WHY DO THIS:  It all boils down to ROI (return on investment), if you are wrapping under 30 pallets a day, this is a very viable, justifiable process with tremendous labor savings and typically a great return on film as compared to hand wrapping.

QUESTIONS ABOUT POWERED VERSUS NON POWERED PRE-STRETCH? Ask answers@highlightindustries.com!

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Heat sealers on stretch wrappers grinds my gears!

Shouldn’t you handle the film correctly and NOT put that bandage on the open wound?

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Wait, how can that be?  Doesn’t Highlight Industries make heat sealers? The answer is: rarely.

Let’s pull back the curtain and show why they are not always needed with Highlight Industries machinery. 

Heat sealers are to seal the film to itself after the pallet has been wrapped.  Sounds simple enough right?  The rub for most is the two primary types of systems out there.  The first is a heated roller that rolls down the side of a pallet (on an automatic conveyor) and melts the film layers together.  The second is a heated tamp pad (typically mounted in the same position).

The problem:

  • Heated Roller : These in theory are great but the combination of heat and the roller make it hard to properly regulate the heat and hold the narrow band between not hot enough and too hot.  Additionally the roller is a high wear item so these have proven to be unreliable and a maintenance headache.
  • Heated Tamp : Although more stationary and fewer moving parts the problem is in transferring a pallet into the area and stopping it in order to heat your seal band.  Costly in throughput and almost equally as unreliable.

Intermission:

The Solution:

Highlight typically will offer you the following deal: if you try our system and feel as though you still need a heat sealer, we will provide it.  In years of building machines, we have built very few!   Go ahead and ask, WHY?

We incorporate Dual Powered Hydro Stretch (DPHS) systems into some of our machinery as our film stretch method (we’ll explain more on this below).  By stretching film at 200%, others will take the tacky film and stretch every 10” into 30” taking all of the tackiness of the film and spreading it out, making it ineffective of holding the film together and creating a film tail (which will impact any automatic handling devices in your production).

Highlight Industries DPHS will have complete control over the film and stretch percentage.  It is really quite simple…reducing or eliminating the stretch at the end of the pallet wrap process (for only a couple of feet of film) will not only reduce the amount of film breaks (we will expand on this in another blog) But it will also keep all of your tackiness together.  The end result is film tails that stay in place. 

Combine that with the wiping process as the pallet exits and you are set for the life of the pallet.  Now you are putting the film to work the way it was intended to be used when you bought it.

Do you have questions about film breaks or anything else? EMAIL ME HERE and we can discuss any breakage issues that you are experiencing.

Happy Wrapping!

 

 

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