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To understand how stretch wrapping works you first have to understand why we stretch wrap loads in the first place.
There are many reasons why we stretch wrap. One main reason is unitizing a load for shipment. Building one large package from many small packages makes it easier to transport, ship and protect individual products from damage. Preventing damage is key to getting loads from their point of origin to their destination in “as made” condition. Stretch wrapping allows us to achieve both goals (unitization for easy transportation and delivering goods without damage) in the most cost-effective way.
Stretch wrapping loads keeps them from moving and shifting during transportation, which is a major source of damage. There are certainly other ways for loads to be damaged during shipment, but stretch wrapping provides a measure of protection that increases the odds of "as made" condition arrival. In turn, that means lower returns, administration duties, credit due to receiver and rework costs - not to mention happier customers and colleagues.
In the 1970's, stretch wrapping machines established themselves as the preferred packaging method for unitizing goods for shipment. Meaning that any company that deals with production, reselling, or warehousing of products probably has some familiarity with stretch wrapping.
To make the best decisions about stretch wrapping machines and film, however, it is useful to understand how the mechanics of stretch wrapping work.
Before the stretch wrapping process can begin a load must first be assembled on a pallet. Once the load is on the pallet, the whole ensemble (pallet and load) is stretch wrapped together.
Assembling the load on the pallet is an important step. Load placement on the pallet is key. The load should not overhang the sides of the pallet or be more than four inches inboard. The pallet itself also plays a role and should be in good condition.
It is important when stretch wrapping not to skip steps that secure the load the pallet. One option is to wrap all the way down to the bottom of the pallet. However, this runs the risk of film punctures from forklifts or pallet jacks when picking up the load. Such large punctures to the film can propagate up the load, causing a loss of containment force and increasing the risk for load failure.
Pallet Grip® is a great solution to lock the load to the pallet and avoid film punctures. The bottom few inches of the film web are automatically rolled into a tight cable at the end of the wrap cycle. The cable is driven down just below the top deck boards of the pallet. This strong cable locks the load to the pallet and leaves enough room to clear forks and avoid the puncture problem.
There are three ways to apply stretch wrap to a pallet of products: manual, semi-automatic stretch wrapper, or high-speed automatic stretch wrapper.
Hand wrapping, as the name implies, relies on people to manually stretch wrap a load. A worker secures the film to the pallet and then walks the film around the load.
Pulling a heavy roll of film around a pallet is wrapping is physically demanding - especially if done right. Imagine the awful dizzy feeling in a hot warehouse. Hand wrapping generally has the highest material cost because there is no consistency of film usage and no substantial pre-stretch. It is also very difficult to wrap a safe-to-ship load consistently.
Semi-automatic and automatic stretch wrappers come in two different machine styles - turntable and straddle. The load is placed on or in the stretch wrapper’s wrap zone and stretch film is applied. Turntable models will rotate the load on a turntable while straddle style models have a wrap arm that will move around the load and apply film. Straddle models do not require the load to rotate. Instead a wrap arm moves around the load, applying the stretch film while the load remains stationary. This type of stretch wrapper is best used for extremely heavy, extremely light, or unstable loads.
These are similar to semi-automatic styles in that a machine performs the actual stretch wrapping of a load. However, automatic stretch wrappers typically include infeed and exit conveyors to automatically cycle loads through the machine.
There are a number of features that can be added to semi-automatic machines that offer some increased automation. For instance, automatically cutting and clamping the film and a remote start lanyard allow fork truck operators to remain safely buckled in their seats on the trucks even while wrapping loads on a semi-automatic machine.
For more help choosing the right level of automation and machine style check out our Stretch Wrapping Fundamentals pages. For instance, how many loads/day may not capture the surges which often occur late in the day as shipments are picked up. So, loads/hour is an important factor to consider.
No matter which type of stretch wrapper you use, containment force is the most important thing to get right. Containment force can mean the difference between a load arriving at its destination intact and arriving damaged and unsaleable. So, what is containment force?
Containment force is what holds the load together. Officially, it's the wrap force times the number of film layers. Wrap force is simply a measure of how tightly each layer of film is wrapped around the load. Film layers are the number of wraps applied to a load at a specific point.
There is no magic formula to determine the right amount of containment force. It is done through trial and error. Wrap, test, change and repeat until you can safely say loads are arriving without damage. Using our over 45 years of experience we developed some Containment Force Guidelines. These are not hard and fast rules, but this chart will give you a good place to start.
Once you've found the right amount of containment force works and the stretch wrapper's settings have been set, it is always a good idea to check periodically to ensure every load is being wrapped correctly. We recommend measuring the containment force once a shift for most operations to ensure the machine settings were not tampered with accidentally or to resolve other issues the machine may have been experiencing, like repetitive film breaks after a film roll change.
Stretch wrapping pallet loads has become a standard part of the shipping and distribution process. We create products, stack them onto a pallet, stretch wrap that pallet, and ship the load. But why, exactly, do we stretch wrap a load? And does understanding the why of it matter?
Understanding why we stretch wrap pallet loads does matter because we wrap loads for more than one reason. Ultimately, stretch wrapping is about loads – unitizing and securing them so they have the best chance of reaching their destination in the same condition they were in when they shipped.
Until recently, figuring out how to do this at the lowest cost was more art than science. Today, the science of stretch wrapping has surpassed the art, ensuring that loads are wrapped effectively, at the lowest cost, and have a better than ever probability of arriving undamaged at their destinations.
A big reason to wrap pallet loads is for protection. This may seem simple enough, but in reality there are a lot of ways that stretch wrap protects a pallet load.
Stretch wrap protects the load from environmental damage. Water and sunlight can damage products during their shipping journey, and stretch wrap acts as a physical barrier. In this same vein, stretch wrap protects from casual damage like scuffing.
Stretch wrap also protects a load from damage during shipping in bigger ways. The process of transporting goods from one location to another is fraught with opportunities for damage; for example, trucks bounce over roads, pallets are stacked high and can fall, products are jostled, etc.
Although stretch wrapping works remarkably well, there are still big improvement opportunities. We estimate there’s about $60 billion products a year in just the food, beverage, and consumer product goods industries that become unsaleable from in-transit damage resulting from ineffective stretching wrapping.
We believe that at least half of that damaged product can be avoided by simply stretch wrapping better.
Another way that stretch wrap protects pallet loads is by deterring theft. It is much easier to see if a load is missing pieces if stretch wrap has been removed or damaged.
So, now that we have a better idea of why we stretch wrap you might find yourself wondering…
Once you understand the why of stretch wrapping it is natural to want to know the how. We get a lot of questions about the how of stretch wrapping. Everyone wants to know how to do it better, more efficiently, and faster.
If you’ve ever found yourself asking these kinds of stretch wrapping questions, we’ve got an answer for you. In fact, we’ve taken our years of stretch wrapping experience and extracted the most important aspects and considerations for the best way to stretch wrap a load and wrapped it up into a quick, 30-minute webinar.
Let’s face it. Machines are better than humans at doing rote tasks, but they’re not better at doing work that requires intellectual decisions. In the world of stretch wrapping, machines wrap loads better than people do. A lot better, actually.
But companies around the world wrap a staggering amount of loads every day by hand. Most of these loads arrive at their destinations just fine, without damage. But many fail during shipping because the loads aren’t wrapped tight enough. This happens, most likely, because during their journey the vibration from the truck causes layers of the load to shift and eventually fall apart. Many recipients will reject damaged loads, return them to the manufacturers, or worse, dump them in a landfill.
The biggest problem with hand wrapping is that operators aren’t as consistent at wrapping loads as machines. Don’t get us wrong, an operator has the potential to wrap several, good loads in a row, but it’s hard to do it well each and every time.
Another challenge that faces hand wrapping is the process of securing loads to pallets. When loads aren’t secured they may slide off their pallets and hit another load damaging the secondary and primary packaging and, sometimes, even the product inside. It’s difficult for people to bend over and wrap film all the way down to the bottom of the pallet over and over again.
Hand wrapped loads that have film applied all the way down to the bottom are at risk for failure. Bad things happen to these loads when forklifts pick them up. Forks puncture the film. Sometimes, the punctured area has a tendency to spread, leaving the load vulnerable.
Lantech stretch wrappers, though, are able to lock the load to the pallet with a tight film cable applied just below the top board of the pallet. The cable placement allows plenty of room for the forks to pick up the load without puncturing the film.
Finally, when it comes to saving costs, hand wrapping doesn't cut it. Machines can significantly cut down on film usage. Stretch wrappers with powered film delivery systems stretch film up to 300 percent, which decreases film consumption by at least half. It's almost impossible for a person hand wrapping a load to stretch the film at the same levels as powered film delivery systems.
So why do so many people still wrap loads by hand when a machine can do it safer, cheaper and more efficiently? That’s one of the many mysteries of life – or at least of the secondary packaging industry.
If you're looking for ways to improve productivity, a stretch wrapper can make a big difference. Here are three ways how it can improve your company's productivity.
Shipping damages are a big source of loss and waste for manufacturers and retailers. 1/2% of all shipped products are damaged in transit because they weren't stretch wrapped properly. That's a $7 billion hit to the economy, as well as a waste of time and energy to fix. For example:
When pallets fall apart in a truck, you use up labor and resources to carefully unload and clean the mess. If products are refused by the receiver and sent back because of damage, it takes additional manufacturing time — with all cost and no profit — to refill the order, which puts other (paid) production on hold.
Proper stretch wrapping prevents tipping, breakage, and pallet loads from splitting apart. Loads arrive undamaged, nothing is rejected, no one needs to clean up a mess, and the production staff isn't working to refill orders for free.
A stretch wrapper can lower your film costs by one-half to two-thirds compared to hand wrapping.
Most wrappers have powered film delivery systems that pre-stretch film as it moves through the system. By pre-stretching film you can increase the yield of each roll. For example, a film delivery system with 200% pre-stretch can turn 6,000 feet of film into 18,000 feet. Modern film delivery systems provide levels of pre-stretch up to 300%. More isn't always better though. It is important to consider the strength of the film you are using. A lower film gauge may not be able to handle levels that high without breaking. Powered pre-stretch film delivery systems start to have a significant economic effect at 15 to 20 loads a day.
Semi-automatic stretch wrappers can also reduce the amount of labor required per load. Generally, if you're wrapping five loads or more per day by hand, you're in the market for a semi-automatic stretch wrapper. The amount of time and energy saved (not to mention the reduced risk of injury) will contribute to the return on investment.
If you're wrapping 400 loads per week, you've got workers spending 30 hours of labor hand wrapping. By using a semi-automatic stretch wrapper you can reduce that to 20 hours of labor per week. A fully automatic wrapper can reduce it to 10 hours of labor per week. If you're paying someone $15 an hour to hand wrap loads, you could save over $7,500 per year just by switching to a semi-automatic machine.
This saved labor can also be transferred to other tasks, or even retraining employees and assigning them to departments that might have labor shortages.
Since its introduction, stretch wrapping has become the dominant method of unitizing products for safe shipment to their destinations. But, it has become so routine that sometimes we lose sight of the fundamentals.
The following five fundamentals of stretch wrapping underlie the process of load unitization and containment.
Before the 1970’s, companies would floor load trucks with individual boxes, a method that was labor intensive and time consuming.
In 1972 Lantech invented the stretch wrapper. Because of its ergonomic and economic benefits, unitizing products on a pallet with stretch film became the most widely used material handling method for shipping products. Instead of taking many workers hours to floor load a truck, now a forklift driver could load an entire truck in less than 30 minutes.
Containment is the ability to hold unitized loads together. It can be accomplished in many ways depending on the load’s make-up. Today, stretch film has become the most popular way to contain unitized pallet loads because it provides effective and economical containment when properly applied. Other less-popular containment methods include dropping large “hoods” over pallets, using shipping containers or securing pieces with bands made of metal, polyester, polypropylene or nylon.
Trucks, trains, boats and planes are ground zero for vibration and vibration is a palletized load’s worst enemy. Vibration is the term used for the destructive forces exerted on a load as its being transported to its destination.
Things like pot holes, curbs, sharp turns, acceleration, sudden stops and turbulence also puts stress on a load. When pallet loads are ineffectively stretch wrapped these stressors can cause layers or products to shift or to slide off their pallets, leading to damaged goods, customer dissatisfaction, excessive costs and unnecessary waste.
Containment force is the total amount of squeezing pressure the film exerts on the load. It is the key ingredient to effective stretch wrapping. Usually measured in pounds and ounces, it’s what holds the load together.
As a load is being stretch wrapped, every layer of film delivers a certain amount of wrap force. When you multiply the number of layers by the amount of force each layer has applied the result is containment force.
Applying the proper amount of containment force is your best defense against loads being damaged during shipment. Make sure you have enough containment force on each load you ship. If you are unsure how much containment force your loads need start by downloading our containment force recommendation chart here.
Never lose sight of why you are stretch wrapping in the first place. The goal is, and always has been, the safe arrival of product loads at their destinations at the lowest cost effectively shipped.
At first glance, a stretch wrapping machine may seem like a luxury purchase, and some may see it as a “want” rather than a “need.” Those who see it as unnecessary are probably not the ones spending their day hand wrapping. What they don’t understand is that a stretch wrapping machine can potentially pay for itself in several ways.
Automating routine tasks frees up valuable time, allowing people to perform other jobs that require critical thinking. And adding productivity features, such as automatically attaching and cutting the film, allows you to configure a machine to your desired level of automation.
Modern film delivery systems provide different levels of pre-stretch. Pre-stretch multiplies the yield of each roll which could save you money on consumables. For example, 200 percent pre-stretch will turn 6,000 ft. of film into 18,000 ft.
The cost of damage is hidden, because it’s a topic most of us want to avoid. The fact of the matter is damage happens and its repercussions are too big for anyone to ignore.
In 2008 the Grocery Manufacturers Association (GMA), the Food Marketing Institute (FMI) and Deloitte Consulting published a joint study discovering the underlying causes of unsellable products. According to that survey, .05 percent of products shipped are unsellable due to damage.
If you’re currently hand wrapping 30 loads a day and shipping $1 million of products annually, you could potentially save $41,715 over 5 years just by switching to a machine that cuts film automatically and has 200 percent pre-stretch.
Here’s a breakdown of labor-saving features that can save you big bucks. Stretch wrappers can…
Your operator avoids getting off a forklift or pallet jack to cut the film after each cycle. By eliminating this process alone, you’ll save 30 seconds of labor per load, or about $7,500 over five years.
You not only eliminate the need to cut the film at the end of the cycle, but you eliminate the need to get off the forklift and press the “start” button on the control panel for every load. Instead, your operator can stay on the forklift, use a remote control to start the machine, perform another task while the load is wrapping, and pick it up when the cycle is complete. We refer to this as Simple Automation- a technology that saves a typical user at least $10,000 over the first year of ownership.
Some stretch wrappers have scales built into the turntables. When you weigh and wrap at the same time, you can eliminate 30 seconds to 1.5 minutes of double handling loads from a stretch wrapper to a freestanding platform scale. That’s eliminating $7,000 to $15,000 in labor over five years. Also, when you weigh your load every time, you lower the risk of paying expensive less-than-truck-load (LTL) re-weigh fees.
The above features save thousands of labor dollars over the life of the machine and provide outstanding ROIs. Even if they’re used as little as 20 percent of the time in a 40 load/day application, they still make economic sense.
*Based on 30 seconds of labor per load to move a load from a stretch wrapper to a platform scale. *Based on $14/hr labor rate. 250 working days/year.  www.gmaonline.org
Imagine you’re a car dealer. You order hundreds of cars to your dealership, but every once in a while a brand new car just won’t start. You do the math and 1 out of every 200 cars doesn’t start, the car isn’t fixable and is a complete loss. Sure, you get to sell 199 cars but you have to take the loss of the 1 car.
Do you think a dealership would just accept the loss? If you do the math, 99.5 percent of the cars they receive are in perfect working order. A 0.5 percent loss doesn’t seem like that much, but wouldn’t it be fair to say that a better scenario would be the dealer being able to sell all 200 cars?
When we’re accustomed to a load damage rate close to 0 percent – what dealerships actually receive – 0.5 percent is a lot. It means that on average, one car in 200 would be a complete loss. It’s pretty easy to see that this is unacceptable.
What's unacceptable for one transportation mode could be the norm for another. Shipping damage (damage that happens between the factory and the point of sale) for the food, beverage and consumer products industries averages about half a percent of gross sales, according to The Grocery Manufacturers Association (GMA) and the Food Marketing Institute (FMI).
The bad news is this amounts to about a $1 billion a year of damage losses in the U.S. alone. The good news is that much of this damage can be avoided.
Shipping pallets of products poses a different set of damage problems. However, they’re problems that can be avoided by using standard processes.
Of these causes of damage, stretch wrapping is the easiest, fastest, and least expensive to improve. And if that’s not enough, more effective stretch wrapping is also the “low hanging fruit” or the “band aid” for mitigating or compensating for the other major causes of damage.
If you’re shipping stretch wrapped pallets, unless you have evidence to the contrary, you’re not doing better than a 99.5 percent success rate. And even if you’re hitting 99.5 percent, it’s not good enough. You’re averaging $50 to $500 of damage per truckload and leaving money on the table.
Or put another way, a $100 million company loses $500,000 a year in avoidable shipping damage. How many more widgets does it have to sell to make up that loss?
Stop wasting money. There’s low hanging fruit to be picked. One half a percent of damage doesn't have to be your norm. Lean processes and principles typically reduce damage and waste by 50 percent or more wherever they're applied.
Okay, we all know the value of a stretch wrapper in a business sense. It keeps things together, it protects items from moisture, it minimizes breakage because everything is sealed tightly together, it keeps dirt and dust off of the products being shipped, and the list can go on and on about the superior benefits of using stretch wrap for packaging.
However, what many businesses don't realize is that a stretch wrapper can also prevent theft of the items that are wrapped, particularly when they are on a pallet. And here's why.
Thieves do like not like to waste time. They essentially want to grab and go, the less time spent creating the crime, the better their chances of escape without being caught. You can look at virtually any surveillance video, and in every case, the lawbreaker gets in and out as fast as they can. They don't stop for a cup of coffee and donuts, they don't hang around and talk to employees, they run in, steal what they want and run out. That in-and-out mentality also works around stretch wrapped items too.
Any item or items that are not stretched wrapped together are easy pickings. A thief can, literally, grab and go and be out of there in seconds with individual items that are not stretch wrapped. But consider this.
If you have a stretch wrapped unitized pallet load sitting out in the open somewhere the stretch wrapping makes it impossible to grab and go. That means every bad guy is going to think twice about even attempting to steal something securely stretch wrapped.
Using opaque or tinted stretch wrap prevents a potential thief from seeing what’s in the load and allows you to see if the load has been taken apart and/or reassembled. Because stretch wrap keeps everything in place, nothing will fall off the load to make it easy to just pick-up and take. Add these intangibles in and you have a winner.
Can any product like stretch wrap guarantee that there won't be any theft? Of course not, but by taking away the main factors for stealing, like knowing what the product is, keeping a load unitized and intact, and grabbing and going, you'll limit the possibility that anyone would want to steal something that has been stretch wrapped, and that's as good as it gets in anti-theft.
Workplace injuries are incredibly expensive - in a number of ways. Lost days, workers' comp premium increases, reputation, impact on worker commitment to the company, overtime, and even the basic ethical cost of not doing everything reasonable to protect workers.
So, it's no surprise that companies work hard to prevent unsafe activities and behaviors that lead to preventable workplace and loading dock injury.
A typical step is to identify high risk activities (on the loading dock bending, lifting, and similar tasks are easy to identify) and implement process changes to eliminate the requirement for workers to perform actions that lead to injuries.
A great example is using a pallet wrapper to reduce the unpleasant and injury prone task of manually wrapping pallets. Hand wrapping is often thought of as inexpensive and expedient. That's a misconception. Aside from not requiring a machine, it typically increases operating cost in several ways:
Hand wrapping a pallet means that a worker will have to lift rolls of film and apply steady pressure as they bend and walk backwards around the load. Rolls can be heavy and, like any other heavy object that is manually lifted, carries risks of back injury. But potential injury doesn’t stop there, hand wrapping also creates the risk of repetitive motion injury.
Walking backward in a circle for any length of time can also be dangerous. Not only can workers become dizzy from the circular motion, but they also can’t see where they are going. Working with no line of sight is seriously dangerous in the busy, sometime chaotic, landscape of a loading dock.
With all of the downsides of hand wrapping, it's obviously an easy place for a plant manager or process engineer to look for opportunities to reduce risks and increase efficiency on the loading dock.
But simply replacing hand wrapping with a machine-based process isn't a universal cure. Things like; throughput, materials consumption and load containment are all subject to a machine’s technical capabilities. And, the machine itself needs to be inherently safe or the ultimate goal of reducing workplace accidents may be missed.
As we mentioned before, a typical loading dock is the scene of lots of activity, with honking horns, opening and closing doors, forklifts zipping to and fro, and loads of products barreling around corners without warning. Amidst all that activity it's easy to overlook some potential injury risks in a simple machine like a pallet wrapper - but that's a mistake.
Safety features you should look for in semi-automatic stretch wrappers include:
It’s important, when shopping for stretch wrappers, to choose a manufacturer with enough experience to know how to build a machine for safe operation. Find a stretch wrapper manufacturer that's built enough machines, and seen enough situations, to anticipate potential problems and engineer around them.
For example, the film delivery system on the Lantech Q Semi stretch wrapper is suspended from a belt which loses tension and becomes slack if the film delivery system encounters an obstacle while descending. A switch detects the slack and stops the descent of the film delivery system thus avoiding injuries.