Tag Archives: Pallet Wrapping

Don’t Buy A Stupid Stretch Wrapper 4: YOU ARE IN CONTROL

So, you have taken the necessary steps, but how do you know nothing will change with your new method?

Lets review the steps taken so far.  You have DEFINED the problem and admitted that you could be better at wrapping.

We walked through MEASURING your current methods to establish a baseline.  Additionally you used the ISTA to ASTM methods to ANALYZE your systems.

Then you IMPROVED your methods (and hopefully wrote the specifications for your packaging).

Now to CONTROL the changes.  There are several methods to verify that the settings of the machine are maintained.  They could range from on board monitoring systems, to cut and weighs, to continued containment testing.

The theory of all is that by wrapping consistently you will utilize the same amount of film on identical pallets.  By incorporating any of the methods into a customer’s PM routine, you will use consistency as your control.

control excellence

Lets expand on the various methods of measuring and how they work: The first is ON BOARD MONITORING.  This system will measure film as it’s applied to the load and report back to the customer via close based servers.  This is the best and most accurate method as it will allow customers to view the data in multiple ways.  It could be linear footage, amount of stretch, cost per load…..the list goes on and on.

The second method is the STRETCH FILM CUT AND WEIGH TEST.  The principle here is the same, but the control is the weight of the film.  You purchase film by the roll, but the resins that make the film are actually sold by the pound.  Using weight is an excellent method to verify cost per load and consistency of wrap.

The last method is CONTAINMENT.  This method is also very accurate as every revolution of film on a pallet will increase the containment force.  By measuring containment, you can verify that your wrapper settings have remained set to specifications.

The last method that can be used is a visual inspection of machine settings; but know that if there has been a film change, or as the machine wears, it will become inconsistent in performance. Different films stretch at different forces; putting on a softer film but leaving the machine at the same mechanical settings will increase film yield but decrease containment force.  Wear, well that speaks for itself, all things eventually wear.  The more play in your roll carriage bearings, the more film can slip through your roll carriage costing you money.  As a side note, this is also an issue with some film monitoring systems.  Because of how film is measured, they cannot account for slip.

Well, that wraps up our “Don’t Buy a Stupid Stretch Wrapper” series.  I hope that you enjoyed it and feel slightly smarter than you did prior to reading this.

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DBASSW Bonus: The Magnetic Film Finger

We interrupt your regularly scheduled program to bring you this important announcement from our sponsor: HIGHLIGHT INDUSTRIES.

So you have been trucking along reading about how to improve your pallet wrapping and now a commercial, no fast forwarding through this like its on your DVR.  This is that infomercial that may actually help you, so don’t consider this a commercial, think of it as sponsored learning.

While we spent time talking about the method of adjusting your machine, there are some additional tools that you may want to make note of.  Since I try to have some fun while writing bear with me while I channel my inner Ron Popeil.

I’m not going to paddle a screen door bottomed canoe around a lake that has been sprayed with a new tangled sealant, or spray paint my head yet, but wait, there’s more!

From the inventor who brought you such great things like Dual Powered Hydro-Stretch, Revolver Wrappers, Synergy Wrappers and everyone’s favorite the Predator Wrapping Family, we have the revolutionary new craze that is taking stretch wrapping by storm:  The Highlight Industries  Magnetic Film Finger, for when dialing in your containment force is too difficult to do because you just cant seem to get enough force without breaking the film!  Magnetic Film Fingers (MFF) are not made of space age materials and are not coated with impregnable Peruvian Yak Hair to limit wear.

film finger

But they are easy to use and their benefit is unmatched.  Mounting to most steel, they can be positioned on roll carriages and bases to provide a small roll of film which is more resistant to tear and propagation.  It’s simple, place the film finger in a position on your machine which allows for the roles end to fold the edge of the film over on itself.

 Seeing is believing, so watch below to see the MFF in action:

 

And watch here to see the MFF used as a bottom roper:

Also know that after your testing is complete, Highlight Industries can provide you a set of adjustable permanent fingers for some styles of machine. Machine sold separately.

 

We now return you to your regularly scheduled Blog.

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High Speed Wrapping and Film Breakage

with Luke Venechuk, Sr Packaging Engineer

speed dial pic

What happens when films are run at high wrapping speeds? Why do films breaks increase so much for these applications? Will the same film perform differently at differently at 12, 24, and 40 RPM?

There are some people in our industry that believe film breaks increase at high speeds because the film heats up and lose its integrity. To find out whether this theory is correct Highlight ran films at different speeds and measured its properties to compare.

The graph below shows a single film being ran at speeds equivalent to 12, 24 and 40 RPM:

graph pic

 

In the graph above we can see that the force to stretch the film (on the left-hand Y-axis) increases slightly as the application speed increases, this is about a 2% increase if we look at the force to stretch at 200% (stretch level is the bottom X-axis, and 200% is within the middle red circle).

We can also see that the stretch at break or ultimate stretch does not change significantly (the right hand red circle).

The increase in force is due to the fact that we’re doing the same work, stretching the film to the same level, in a shorter amount of time, which means we have to pull a little harder to end up with the same result.

There are some small differences that take place for the film at different speeds, but it’s certainly not anything that would cause the film to break.

So what is causing film breaks at high speeds?

Highlight found that the cause of most film breaks at high application speeds is due to poor corner compensation. Corner Compensation is a system within most stretch wrappers that increases the film payout rate for the corners of the load and slows the film speed on the sides of the load while wrapping, usually by changing the speed of the prestretch rollers throughout the wrap cycle

Here’s a top view of a rotating load:

rotating load pic

Corner Compensation is needed as the film demand is constantly changing as the four-sided load rotates. Here’s an example of a changing demand rate through one revolution of wrapping:

graph 2

As we wrap faster and faster, the equipment has less time to change its film speed, so the rate of acceleration for the film delivery gets exponentially higher.

At 12 RPM the film goes from 131 to 200 ft/min in .66 seconds. At 50 RPM the film goes from 550 to 835 ft/min in .16 seconds.

graph 3

This rapid acceleration creates more stress and is the reason why we see more film failures at high wrapping speeds. This is compounded by the fact that many corner compensation systems perform worse as they age, becoming “out of sync” with the wrapping needs of the rotating load.

What’s the solution to all of this?

The correct approach with the film or the equipment can reduce these film breaks.

For the film: high ultimate stretch levels allow films to absorb sudden spikes in stretch levels without breaking. It may be possible that very stiff films will resist stretching when exposed to spikes in stress.

For the equipment: The best solution is to fix the corner compensation system. Highlight responds to corner demand and changing film feed rates without the constant acceleration and deceleration of the prestretch roller, where the most stress on the film occurs. By moving our corner compensation from the high stress area of the prestretch section to the low stress area after that we can almost completely eliminate film breaks due to corner compensation at high speeds.

For more information visit www.highlightindustries.com or call us at 800-531-2465