Standard Stretch Film

Stretch Film is the highly elastic plastic material used to wrap products and secure them onto pallets. It is made from LLDPE and is the ideal material for wrapping and securing loads because of its flexibility. There are two types of stretch film: regular and pre-stretched film. To learn more about Stretch Film, click here. 

The terms shrink wrap and stretch wrap are often used interchangeably, but the reality is, they are two different products. Unlike stretch wrap, shrink-wrap is a clear plastic film that is not stretchy. Shrink film also requires heat to cling to the product and is usually safe for direct contact with food.  Click here to learn more.

Represents Stretch Film

Does not represent stretch film, but instead, shrink film

There are three methods of stretch wrap application: manual, semi-automatic machine, and high speed automatic machine.
  • A manual hand wrap requires workers to wrap a load by hand. Workers attach the film to the pallet and then use a roll of stretch wrap on a bar to wrap the film starting at the base and then walk around the load to wrap the load entirely
  • Semi-automatic stretch wrappers have the machine perform the actual stretch wrapping. On semi-automatic stretch wrappers, the pallet is placed on a turntable rotating the pallet as the film moves up and down.
  • High speed automated stretch wrappers usually incorporate conveyors to automatically cycle loads through the machine for increased output and efficiency. Automatic stretch wrappers apply and cut the film, so the only thing you need to do is change the film roll.
Regular Stretch Film
  • Regular film is un-stretched film. It is primarily used together with stretch wrappers that contain a pre-stretched unit.
  • Regular film per roll costs higher than pre-stretched film, but still has the ability to stretch after is placed on a film roll.
Pre-Stretched Film
  •  Pre-Stretch is the process of elongating film to a percentage of its original length. It’s usually 200-300% of its original length prior to to being put on a roll.
  • Pre-Stretching film has allowed the process of stretch wrapping to be a more affordable way to secure items during transport and have better load containment.
Force-to-Load is a measure of how tight the film is being pulled as it exits the carriage and is applied to the load. Force to load plays a key factor in maintaining a percentage of pre-stretch. Although force-to-load does not hold your pallet, the amount applied does contribute to all around containment force.
Containment force is the amount of load retention created due to the film’s stiff properties. Containment force is the property that holds your pallet together during transit.  To evaluate the performance of your stretch film and application process, there are several testing methods that can be employed. These methods include using a film force pull plate, pull bar, double finger, or even replicating the delivery of a pallet via freight truck with a vibrations or tilt test. For more information on containment force, read about it in our blog

Pre-Stretched Film

Pre-Stretched During Manufacturing

  • The film is stretched during the manufacturing process prior to being wound up in rolls for stretch film application. Here’s a video of the process.
  • Hand wrapping using pre-stretched film rolls doesn’t require an operator to pull as much as a traditional stretch film- an key reason why the majority of pre-stretched film is applied using hand wrap dispensers.
  • Pre-Stretching film (not to be confused with pre-stretch carriage on a stretch wrapper) before winding on a roll has allowed the process of hand stretch wrapping to be a more affordable way to secure items during transport and in some cases have better load containment.
  

Pre-stretched Using a Stretch Wrapper

Traditional stretch film that is elongated using a pre-stretch carriage on a wrapper. The film is stretched during the wrap application process using either a break or motorized pre-stretch carriage.
  • Break Pre-Stretch Carriage This type of carriage contains a break roller. The break provides resistance causing the film to drag, which increases the tension between the load and film. Although this method does save a portion on film, it doesn’t have the same stretch capabilities as a powered pre-stretch mechanism. Click here to watch a video of a stretch wrapper with a mechanical break.
  • Powered Pre-Stretch Carriage The film passes through two film carriage rollers running at different speeds. The film gets pulled between the rollers and is stretched prior to being applied to the load. Using this method film will stretch between 200-300% of it’s original length. To see how powered pre-stretch works, check out this video
  • Pre-Stretched Rolls run at a higher cost per pound than Regular Film but at a lower roller price. However, finding the lowest cost per pallet doesn’t mean buying the less expensive roll, it means spending the least amount on wrapping without sacrificing the load integrity.
  • Pre-Stretched Film also can’t be expanded any further, whereas Regular Film can expand with a stretch wrapper containing a pre-stretched feature; thus increasing load-holding force.
  • The advantage of operating with a powered pre-stretched unit is that it stretches film resulting in greater load stability and allows you consume less film per pallet.
  • Whether you purchase pre-stretched film or regular film, you can’t stretch the film any longer without a pre-stretched unit. However, a quality stretch wrapper with a powered pre-stretched carriage can stretch regular film 2-3x more than a machine without one.
  • A stretch wrapper with no pre-stretch carriage simply contains a roll of manufactured pre-stretched film that lays the pre-stretched film on the pallet without stretching further.
  • By purchasing a stretch wrapper with a powered pre-stretch carriage, you’ll achieve better load holding force at a cheaper cost for your loads.
  • The initial investment of buying regular film may some pricey but using pre-stretched film with a regular wrapper will end up costing you more in the long run
  • Stretch wrappers give consistent stretch. Max stretch by human is around 15% and is inconsistent.

Did You Know Purchasing Un-stretched Regular Film Could End Up Saving You More Than Purchasing Pre-Stretched Film?

Here’s How…

A 20” roll of manufactured pre-stretched stretch film costs about $31.35 per roll and gives you 5,000ft of surface area to work with, while 5,000ft of regular stretch film costs $64.00 per roll.

1 Pre-Stretched Roll  20” x 5,000’ =$31.35

1 Regular Roll              20” x 5,000’ = $64.00

Naturally, the $31.34 of previously pre-stretched film would appeal to most plant managers. However, when operating under the correct settings, there could be more to gain from stretching film using a stretch wrapper.

If you have a quality stretch wrapper that is operating at 200% stretch (80% of its ultimate-stretch**), the regular stretch film at $64.00 per roll could potentially give you 15,000 ft. as opposed to the manufactured pre-stretched film coming in at 5,000ft.

Pre-Stretched = 5000’/$31.35= $.00627 per foot
Can’t get stretched anymore

Regular = 5000’/ $64.00 = $.0128 per foot
Using a pre-stretch carriage on a wrapper, this film will stretch 3x as more at 200%

  = Equiv. 15,000@200% = $.004267 per foot
     5000ft. of regular film is really 15,000ft. when using a pre-stretch wrapper.

PRE-STRETCHED VS. REGULAR FILM

Pre-Stretched @ $ .00627 per ft vs. Regular @ $.004267 per ft.*
15,000ft. of Film $94.05 vs. 15,000ft of Film – $64.oo*
*Highlighted portion indicates better value

Common Misconceptions

#1. Pre-stretched hand wrap greatly reduces the amount of labor required to wrap a pallet.

FACT: Although hand wrapping using pre-stretched film reduces the amount of energy exhausted by the worker, obtaining a machine that has a pre-stretched unit requires little-to-no energy. Thus, pre-stretching the film using a stretch wrapper ultimately retains the health, energy, and safety of your employees more than pre-stretched film does.

#2. Stretching the film activates its elastic memory, triggering the film to return to its original state.

FACT: On the contrary, film does not have elastic memory. Stretch film doesn’t go back to its original form. Once film has been stretched between 70-80% of ultimate stretch, there’s no more stretch to give. When a load is being transported on a rocky truck, what keeps the pallet from toppling over is film resistance. It can’t get any looser because it has already been stretched to 80% of ultimate. On the contrary, when the film is not stretched enough, it can become loose once the pallet shakes resulting in a poorly secured load.  If the film is not stretched to 70-80% of ultimate, most managers over-compensate by using more film to tightly secure the load. Managers will use more film because it  requires more energy to stretch more film (or thicker film) than less film.  However, if the film was already stretched to 80% of ultimate (80% is usually where the film required a ton more force to stretch just a little) the energy required to stretch will be equivalent to the energy required to stretch more film, or thicker film.  Thus, less film stretched at 80% will require the same energy to stretch more than heavier film stretched at 60% of ultimate. All in all, you achieve better load holding force by stretching the film yourself using powered pre-stretch wrapper.

#3 Wrapping with pre-stretched film will save you money.

FACT: Although regular stretch film comings in at a higher cost, it winds up more valuable than pre-stretched film because you’re getting more use of regular film while consuming less. By choosing to stretch your film using a powered stretch wrapper, you save money on film and overall lower operating costs.

#4 Producing Pre-Stretched Film using a Stretch Wrapper is always the best option 

FACT:  Not all stretch wrappers product the same results. Most stretch wrappers stretch up to 200%  whereas, higher end stretch wrappers can stretch up to 400% and beyond. Most standard film will stretch at least 300% requiring 240% stretch to get to 80% of ultimate.  Most high end films ultimate stretch will be 375%+ stretch requiring your wrapper to stretch at 300% consistently making it impossible for humans and most machines.

The same occurs if you put a high end film on a machine (ultimate 375%, machine stretch 300%) and only stretch 200%. As the pallet vibrates on the truck, the film can stretch another 100% causing the film to loosen as the pallet travels.  The quick fix that most managers implement here is using more film on the load to minimize the stretch, but it might be best to upgrade a machine that can stretch at 300%.

BOTTOM LINE

If your operation requires that you only wrap 3-5 pallets a day, you should be using pre-stretched hand film. However, if you’re wrapping more than 10 pallets a day, you should use a stretch wrapper and film that has been tested to work together and stretch the film at 80% of ultimate in order to achieve greater load holding force at an overall cheaper cost.

 

If you’re in the market for a new stretch wrapper, contact the experts at Best Packaging by clicking here, or calling (888) 930- BEST. We’ll help you choose the right machine for your application.

Call Now Button888-930-2378