Pallet Wrapper Control Setting Recommendations

HOW-TO INSTRUCTIONS:
What should my pallet wrapper settings be to properly secure my loads for shipment and reduce my stretch film costs?

Goals:

  • To properly secure the load for transport (keep loads from falling apart in the truck)
  • To provide protection against dirt and moisture (helps to keep products clean and dry)
  • To provide theft deterrence (make it harder for people to steal products)
  • To minimize packaging costs (save money on the cost of film by preventing needless over wrapping of your loads)

 

Applicability:

  • This guidline describes the most common wrap type, a Wrap Up Down pattern.
  • Other patterns, such as Wrap Up Only, Bottom Wraps First, etc. encompass the same wrapping philosophies, with obvious differences.
  • This guidline is suitable for use with any industry standard pallet wrapper, conventional film dispenser, non-prestretch carriage, powered pre-stretch film carriage, semi-automatic, fully automatic, high profile, low profile, rotary tower, etc.
  • There are many differences in the way these settings are changed, that vary from one machine to the next.  Reference the manual for your model machine for instructions on how make the noted adjustments.

 

Before you start:

  • Produce a skid of product to use as the primary test load that is representative of the largest load in terms of width and length.
  • Ideally this load should be composed of product that you can afford to get damaged if something doesn't go well.  For example: a load gets toppled over, or boxes get squeezed from being wrapped too tightly.
  • In order to set up the overwrap settings, this load should be shorter than the maximum wrap height capacity of the wrapper, ensuring that the Auto Height Photoeye will be used.
  • Produce a skid of product to use as the secondary test load that is representative of the smallest load.
  • Set the wrap pattern (type) to a Wrap Up Down program.
  • Load the stretch film into the machine.
  • NOTE:  Have a knife ready to cut off the stretch wrap that will be put on the test load.
        a) The test load will eventually be over-wrapped and need the film to be cut off.
        b) also, the multiple layers of stretch film might get white and shiny enough to cause the Auto Height Photoeye to fail to reliably recognize the top of the load, leading to set up issues.

 

Quick Steps:

  1. Start a wrap cycle.
  2. Adjust the turntable speed to approximately 2/3 to 7/8 of maximum speed.
  3. Adjust the film force to the desired tension.
  4. Adjust the film carriage up (raise) speed of the film carriage until there is an overlap of approximately 4" (100 mm).
  5. Adjust the overwrap height such that the film folds over the top of the load and creates a band around the top of the load that is approximately 4" (100 mm) wide.
  6. Set the top wraps count to at least two (2) revolutions.
  7. Adjust the film carriage down (lower) speed to a fast rate.
  8. Set the bottom wraps count to at least two (2) revolutions.
  9. Repeat wrapping loads as necessary until satisfied with all settings.

 

Detailed Steps:

 

1. Start Wrap Cycle

  1. Attach the film tail to the bottom of the load. (Typically it is tied it to the pallet, tucked between boxes, or pulled under the load.)
  2. Start the wrap cycle
       
  3. Proceed to the next step.

Comments:

a) In semi-automatic wrappers, there is a typically a 'Start' pushbutton.

b) In automatic equipment, select 'Auto' on the main control panel, or if a load is already in place, push the 'Rewrap' pushbutton.

 

2. Set Turntable Speed

  1. Adjust the turntable speed to approximately 2/3 to 7/8 of maximum speed.
  2. Proceed to the next step.

Comments:

a) The turntable speed is the first thing to be set in the controls because several of the following steps are affected by this setting and all would need to be re-set if this is changed.

b)  Most wrappers have a maximum turntable speed of anywhere from 10 to 15 RPM.

c)  Some wrappers come with this value preset from the factory, while others use a speed dial or operator selector of some kind on the control panel of the machine.

d)  Some wrappers (typically automatics) have this speed controlled by settings directly on the drive board or in the PLC program.

e)  We recommend not running the turntable at full speed unless the loads are very stable (before being wrapped).

f)  Rotary arm wrappers do not run the risk of loads falling apart due to rotation speeds, but something less than full speed is still recommended.

 

3. Set Film Force / Tension

  1. Adjust this setting until the film is tightly being applied to the load, but not so much as to come close to breaking the film.
  2. Proceed to the next step.

Comments:

a)  This setting controls the amount of tension (aka. post-stretch) that is put on the load after the film comes out of the film carriage.

b)  In a machine equipped with pre-stretch, the film has already been stretched inside the film carriage, and will naturally tighten on the load as it sits there over the next few hours, so this setting doesn't usually need to be set to a very high value.

c)  Establish this setting before proceeding to the next step because as the tension is increased, the film will 'neck down' more and more, narrowing the film web, and affect the amount of film coverage on the load with each revolution.

d)  Check the loads after they have been wrapped and been sitting in storage for a few hours (or days).  If the product is susceptible to crushing, and this setting is too high, there may be damage to the load.  If so, reduce this setting.  Trial and error with the settings of the wrapper, and the proper selection of film, will help to produce satisfactory long term results.

 

4.  Set Film Carriage Up / Raise Speed

  1. While the film carriage is raising, look at the amount of film overlap that occurs from one layer of film to the next as the load (or tower) rotates.
  2. Adjust the up speed of the carriage until there is an overlap of approximately 4" (100 mm).
  3. Proceed to the next step.

Comments:

a)  The intent of this setting is to completely cover the product for cleanliness and theft deterrent purposes but apply as little film as possible.

b)  Setting this speed as high as possible (while maintaining overlap) minimizes the time it takes to reach the top of the load (decreasing cycle time, increasing load throughput, and minimizing film costs).

 

5. Set Overwrap Height

  1. Adjust the overwrap height such that the film folds over the top of the load and creates a band around the top of the load that is approximately 4" (100 mm) wide.
  2. Proceed to the next step.

Comments:

a)  This setting controls how much extra time the film carriage raises above the top of the load after the Auto Height Photoeye senses the top of the load.

b)  Many film carriages have a means to mechanically adjust the position of the photoeye to adjust this.

c)  Other film carriages use a timer in the control system to cause the film carriage to keep raising after the photoeye senses the top of the load.  In semi-automatic wrappers this timer is usually operator adjustable using the control panel.  In automatic wrappers, this value is often programmed into the PLC.

d)  Many wrappers have both of the above means to make this adjustment.

e)  On a turntable style wrapper, if the load is taller than the wrapper is built for, the film carriage will stop raising when the film carriage reaches the maximum upper limit of travel possible, and the film will not wrap over the top of the load.  In this case, the settings for overwrap have no effect, and the wrap cycle will carry on without issue.

f)  If the top layer of a load is not complete, and there are extra boxes (products) left over, build the top layer of these loads such that these extra boxes (products) are placed in the corners and/or the outside edges of the load.  Then, increase the overwrap setting (beyond the 4" recommendation) such that the film carriage raises an amount sufficient to catch these extra boxes (products) and secure them with the wrap.

 

6. Set Top Wraps Count

  1. Set the Top Wraps Count to at least two (2) revolutions.
  2. Proceed to the next step.

Comments:

a)  This setting controls how many revolutions the load (or the tower) will continue to rotate after the film carriage is at the top of the load, and before the film carriage starts to lower.

b)  Two (2) top wraps is the recommended minimum for this value because it guarantees at least one full revolution of film at the top. (Explanation - Considering that there is a delay in time for the stretch film to actually reach the top of the load after the film carriage stops raising, if this value is set to only one (1), it is conceivable that the film carriage could count one revolution and start lowering before one complete wrap has actually occurred at the top of the load.)

c)  Note that a significant portion of the load unitization that keeps the loads from falling apart during transport is provided by the top wraps on the load.  Therefore, if extra load retention is required, the single most significant setting to be changed is the top wraps count.

d)  Most wrappers allow up to nine (9) top wraps to be applied, however, rarely is there a need to go beyond a count of four (4) top wraps.  Industry practice finds that four (4) top wraps is fairly significant, and applying any more than that simply drives up the packaging costs, increasing wrapping time, and reducing throughput.

 

7. Set Film Carriage Down / Lower Speed

  1. Adjust the film carriage down speed to a fast rate.
  2. Proceed to the next step.

Comments:

a)  This setting controls how fast the film carriage lowers to the bottom of the load, following the completion of the top wraps.

b)  Since the load has already been secured by the wrap during the film carriage raise portion of the cycle, and structurally secured during the application of the top wraps, there is no need to manage overlap, and the film carriage can go to the bottom as fast as possible in order to minimize wrap cycle time, and reduce film usage.

c)  However, if extra load retention in the middle of the load is required, slowing the film carriage down with this setting will apply extra film to the middle of the load and improve the integrity of the load.  Note that slowing this down more than necessary only increases packaging costs and slows down the cycle time of the wrapper.

d)  Changing this setting (instead of changing the film carriage up speed) to improve load retention in the middle of the load is preferred because changing this setting does not force the overwrap settings to be re-set.

 

8. Set Bottom Wraps Count

  1. Set the Bottom Wraps Count to at least two (2) revolutions.
  2. Proceed to the next step.

Comments:

a)  This setting controls how many revolutions the load (or the tower) will continue to rotate at the bottom of the load after the film carriage has reached the lower limit, and before the turntable (or tower) shifts into slow speed to park at the start (home) position.

b)  Two (2) bottom wraps is the recommended minimum for this value because it guarantees at least one full revolution of film at the bottom.

c)  These wraps help to secure the load to the pallet so it doesn't shift in transit.

d)  Most wrappers allow up to nine (9) bottom wraps to be applied, however, rarely is there a need to go beyond a count of four (4) bottom wraps. Industry practice finds that four (4) top wraps is fairly significant, and applying any more than that simply drives up the packaging costs, increasing wrapping time, and reducing throughput.

 

9.  Repeat (as necessary)

  1. Repeat wrapping the test load multiple times until everything is set your satisfaction and needs.
  2. Cut the film and tuck the tail under the wrap.
  3. Repeat from step 1.1 as necessary.

Comments:

a) After the largest test load has been satisfactorily set up, then repeat the process with the smallest test load.

b) Adjustments to the settings may be required and through trial and error the best settings can be found.

c) If the wrapper is equipped with a 'quick select', 'wrap program', 'independent settings switch', 'pattern selector switch', 'multiple wrap settings', 'recipes', etc. feature, it could be possible to set up another wrap program to better suit this smaller load size.

 

Final Comments:

Do not assume that all settings are necessarily optimized to your needs after your initial set up.  Monitor your loads on a regular basis, from the time of wrapping, while they sit in your warehouse, to when they are put onto trucks for shipment, and after they have arrived at your customer's location.

The type of stretch film that you are using may also be optimized.  Work with your film supplier on a trial and error basis to optimize your wrapping efficiency, and reduce your materials costs while maintaining load integrity during transport.

 

Other Comments:

Alternate Set Up

There is another way of setting up your wrap pattern, which typically works just as well, and the use of which is a matter of preference.  This alternate pattern has the film carriage raise to the top as fast as possible, and then has the film carriage lower at a speed which provides the desired overlap of film.

Outside Storage with Top Sheets

If wrapping for outside storage, one would typically wrap with overlap (i.e. raise slowly) to the top, pause the wrap cycle, apply a top sheet, then resume the cycle during which the top sheet gets wrapped in by the top wraps.  This produces a 'water-proof' wrap.