I already have a Stretch wrap machine, I can't save more money.....CAN I?

You know what I think.....

I recently had an appointment that had taken an all to familiar turn.  If I had a dollar for each of the calls that I made where the customer had the false impression that he had saved every penny that he could have already.  They have already invested in a machine and it featured a powered pre-stretch system, and secured great film pricing.  Only to find out that they purchased from an uneducated sales knucklehead, who left money on the table....the customer's profit.

One of the greatest mis-conceptions in stretch wrapping is that just because you use a machine, you are saving money in film.  Many machines poorly stretch film in spite of the fact that they have pre-stretch systems.  Let's examine the reasons.

1. Own/inherited an old machine : Old machines fall into many potential problem categories.  Most will be covered below.
2. Roll carriage:
1. Rollers damaged or worn: Many times when you look into the carriage you will find that the pre-stretch rollers are cut up or worn out.  This means that there may be either slippage and/or scar-ation of the film.  Slippage occurs when the rollers do not have enough grip on the film to pull effectively.  More will be covered regarding design that impacts slippage.  With regards to damage, look at the rollers.  Operators tend to take knives to the roller coatings and slice them leaving them to over time dry rot.  This will create large gaps in the roller which will keep the film from properly adhering to the roller and create a bad mark on the film which may lead to pre-mature breaking at lower forces.
2. Door not secure: Multiple machines that I walk up to have a roll carriage that is poorly mounted to the front of the machine.  As a result, there is movement when running and the door will not hold the film against the pre-stretch rollers.  Therefore, with inconsistent pressure, the film will tend to slip across the roller.  maintenance may or may not be enough to fix this problem.  It depends upon what additional damage may have occurred as a result of the poorly mounted door.  ONE MORE security issue for the door is the latching mechanism.  Many times, it is not the hinge side but the latch side that is not holding.  This leads to the same item above, film slipping across. Make sure that the latching mechanism is both secure and sound in its construction.
3. Design:  This is a slippery slope because everyone like to think that they use the best method.  I'll tell you what I think but first lets look at the below graphic.
   
4. As you can see there are three prevalent designs in the threading of film through a roll carriage.  Here is MY OPINION after working for over fifteen years with thread patterns.  New all systems will work but in a short period of time you will start to see large differences between them.  I believe that I have the sketches ranked in their long term effectiveness with the best being the top of the chart and the quality decreases as you go down the chart.  S-Style provides excellent film/roller surface contact.  This system does not allow for the fastest threading but typically these style of rollers are larger diameter (in some cases twice the diameter) which significantly increases the surface contact area between the film and the roller.  This will mean less slippage.  W-Style is my second favorite because although rollers are a smaller diameter (typically) than the S style, it maximizes the contact surface area over a smaller  roller versus the U-Style which frankly is a very poor design (This BLOG is called YOU KNOW WHAT I THINK...NOT....You know what you think :)   ).  It only goes without saying that the slippage will be exponentially increased with the U-Style because there is only about 90 degree contact surface area over the pre-stretch roller versus the 180 degrees on the W-Style.
3. Temperature:  Did you guess this one?  Stretch film in a cold room will perform much differently than if you are running it in a warm room.  WHY?  Well without getting scientific (because I am a packaging guy, not a scientist), the film in a cold room will become brittle.  The tackiness (not how I dress, but what makes film stick to itself) does not have the ability to grip on the roller so the colder it gets, the more the film slides through the roll carriage.  There are some methods to address this issue so if you have this as a problem please let me know and I will help you overcome it and get back on the savings road.

So what it all boils down to is.......HOW DO YOU KNOW IF YOU ARE LOSING MONEY?  Allow me to provide you with the simple test to see how much money you may be leaving in un-stretched film.  No special tools required here, just a simple business card.  Once a pallet is wrapped, take the pallet, and this is the hard part, find a single layer of film.  I start with the tail and without unwrapping the load walk back with my hands to the single layer only but at least half way around the pallet from the film tail (that is the hard way to say opposite side of the film tail).  Do this in the middle of the pallet length (not too close to either corner).  Now at the top of the film grab it  between your thumb and index finger and have your hands about 3.5" apart (the width of the business card).  Now slowly and evenly pull your hands apart.  You will get to a point where the film will stiffen then break.  At the point that the film becomes stiff (just before breaking) press the film on the pallet and measure how far apart your fingers were (what did you stretch your 3.5" to).  If you are more than 8", you most likely would benefit from a new machine, or potentially additional service on yours.  If you are less than 8" you are probably pretty good.  

WHY PROBABLY?  It depends on how your stretch occurred.  Pre or Post stretch.  Those will be covered in another BLOG but rest assured that either way, for now, your machine is providing enough control over your film to wrap without breaking.

That's what I think!