The topic of “Machine Force Settings” is often surrounded by misconceptions and ambiguities. Let’s start with explanations of some of the terms used in the industry. What is machine force and what are machine force settings?

Well a machine of force setting simply refers to either a mechanical or an electrical means of varying how tight the film is actually applied to the product that is to be wrapped. The force settings refer to any type of indication of what that force is somewhere on the machine itself.

What is the difference between “Machine Force Settings” and “Force-to-Load”?

The settings themselves are merely a percentage of what the machine is capable of producing. The force settings themselves can be different between different machine manufacturers even in and of machine brands themselves. They are simply terms by different manufacturers to describe this same process. Just as a beverage company may say that their beverage is a cola and another may say that the beverage is a soda. It really means the same thing. A simple definition would be how tight the film is applied to the product. The important thing to remember is that it is variable and it is a measurable tangent. It simply relies on how each machine is calibrated.

Why is this such a misunderstood topic?

Well that’s a good question and we get that question often. You have to realize that there are so many stretch wrapper manufactures in the marketplace compared to a large machinery manufacture like a bottle filler maker or manufacturer. With larger and more specialized equipment the sales force is generally smaller and usually factory direct. That knowledge base of that kind of product is contained to a select and specialized group of salesmen.

With the number of wrapper manufacturers combined with a relatively low price, compared to say a turnkey filler machine, you wind up with a large group of distributors that are selling basically the same product. Now this is good for wrapper manufacturers by the way of the sheer number of units that can be sold but it’s also a double edged sword. If we think about it, wrappers are generally sold through a distribution network. These distributors can carry between twenty, fifty, seventy lines of manufactures. It’s difficult to be a master of a type of machine when you have to be knowledgeable across all of these lines. Now if we combine this with the branded terminology from different manufacturers a straightforward topic such as how tight the film can be applied can get really confusing to a sales force, not to mention confusing to an end user.

Are force settings the same from one system manufacturer to another?

Yes the settings are basically the same but it’s not as simple as these guys may use a dial to set the film force or these guys use a keypad. Different manufacturers come to the same outcome differently. We as the manufacturers use different technology to vary the film’s containment force applied to the load. Some manufacturers will use a purely electronic control of the film. Others may use a combination of electrical and mechanical means of varying force.

One manufacturer’s forced settings at 30% may yield 30 pounds of force and another’s forced setting at 30% may yield 45 pounds of force applied to the load. It all has to do with how the machine is calibrated. Keep in mind that not only film force settings differ between the manufacturers but they easily can be different between two identical machines.

Are there differences in the force settings used between rotary arm and turntable wrapping systems?

Well not really as long as we are talking about both types of machines being built by the same manufacturers, same carriages, etc. I have seen differences in film, but the differences are more due to the film than the machine and I’ll explain that. If both types of machines have identical carriages and the controls are calibrated identically then the force applied by the machine to the load would be equal. The differences or the anomalies would lie in the fact that most overhead rotary machines have a greater distance between the carriage and the load. Now this increased distance can allow film to absorb some of that tension that is applied and ultimately lose some of the force.

Over the years you have certainly had an opportunity to see how misunderstandings and poor information can negatively impact on company operations. How do misconceptions about force settings compromise output results?

Force settings are really an important part of how a wrapper operates. It’s measurable, it’s tangible, and it’s viable. It does allow shipping managers the ability to maximize their load containment and insure that their product gets from point A to point B in a repeatable condition. The misconceptions that we are talking about often stem from a department that set up their matrix of how the wrapper’s force or tension setting must be at to achieve a preset film force. Many times they don’t really understand the dynamics of the stretch film or the workings of the wrapper itself.

Most users or managers will use a pull test on the load and come up with a desired film force. Then they’ll note the setting on the control panel that achieved that goal but there’s no real standard for pull testing. Unfortunately they think that every machine should be set at whatever force settings they came up with and nothing is going to change. They don’t take into consideration the environmental factors such as machine wear, inconsistent film, machine calibration, low voltage in a plant one day, old parts on a machine. All of these factors must be taken into consideration when you are setting up a force test. Unfortunately people don’t think to check these things. They just think that they should get force X if the machine is set to preset Y. They really have to understand that there are a lot of variables that go in to coming up with these pull test settings.

Discuss some of the variables that can directly affect machine force settings such as application speed, load types, and weight & height.

Absolutely these are all real good examples. We can start with application speed, or how fast the machine is actually rotating around the load or how fast the load is spinning. Application speed can have an effect on poor settings for sure but bear in mind that the better the model of the machine is or the better that the carriage is, the more consistent it will be as the rotational speed and feed rate demand increases. Most manufacturers offer different levels of machines. Each one of them has there place in that market. A slow running, low production rate machine or application is usually not an issue. As speed requirements increase the film’s stretch and force compliance can wind up being an issue. This is where your premium machines or premium carriages have an advantage due to being more responsive to the corner demands.

How about Load types?

Load types can be another issue simply due to how fragile one load may be in comparison to another. If we are wrapping bricks and cement blocks and things of that nature you can put a huge amount of force on to that product. If we are wrapping a stack of light bulbs where the entire product can weigh only about a hundred pounds you have to be very careful on how you wrap it. So force has a lot to do with the load type and vice versa.

What about weight and height?

Load weight has a lot to do with how tension is applied. Heavy weight loads will allow more film tension to be applied; light weight loads, such as a stack of empty plastic bottles, require a light touch and can be an issue for some types of machines. Load height can easily be an issue because high film tension can simply just topple a really tall load if we are not careful. This is why manufacturers put indicators on the front of a panel so that you can change the amount of force that is actually applied to the load.

If a company has several wrappers from different manufacturers is there a single machine force setting that can be applied to all of the wrappers that will deliver the same on-pallet-force?

That’s a great question and we do get that quite a bit. The short answer is “No”. Unfortunately there is no way to really get an across the board setting that’s going to be equal across the board. It’s just not going to work because of some of the factors that we spoke of earlier.

I always use this analogy in some of my classes I teach that describes the differences between manufacturers’ machines. You know if you go to a home electronics store and you are looking at a hundred watt stereo. Do you really expect that the Sony system over here is going to give you the same volume, tone, imaging, surround depth, you know, at a five setting as the Pioneer system at the same volume.

Different manufacturers do their manipulation of the film in different ways and combine that with maybe different ages of the machines, different revisions, different evolutions of the same machine perhaps they bought one in 95 and now they bought their second one in 2000. You combine that with how the machines are calibrated, how well each machine has been maintained. There are just too many factors to get multiple manufacturers with different machines into a single plant all reacting to the load at the exact same indication on the front panel. It’s a little unrealistic.

Is pull-plate testing the only way to accurately determine on-pallet-force for any given load?

Absolutely and that’s generally the way most of your more educated plants will actually look at their force setting requirements. Doing things like a pull test and even stretch tests and some other type of tests that are in the industry, we can certainly come up with providing the load with the same amount of force regardless of what’s indicated on the front panel. Testing is the key. You really have to get out there and test regularly in the exact same manner. That’s really the important part. It all comes down to the telltale of the film pull.

Since on-pallet-force is integral to successful load containment, why don’t we see more education and training in the market about testing standards like ASTM D-4649?

We certainly try to train personnel on repetitivity. We want the same test all the time. Now unfortunately many customers do not know of established standards for pull or plate testing.

I would dare say a large percentage of the companies that are out there have come up with their own tolerance test and that’s fine as long as it’s repetitive; as long as you adhere to that. The best way to do it is to simply establish a base line across all of your wrappers in your plant and that includes all manufacturers. If you can get a base line then what needs to occur is simply come up with a setting on each machine that says this machine establishes this amount of force on the load at this setting and simply go on to different machines. The ideal result is to have the same effect on each load . . . . not what is on the dial but what is on the load.

Is there a standard that wrapper manufacturers could adopt to make applied machine force universal?

I’m sure that PMMI is actually working on that as we speak. You have to remember that there are so many manufacturers out there that getting them all together is one huge feat and that’s going to be a great accomplishment if somebody can pull that off. I know that that’s been discussed at many company functions, many trade shows, a lot of the different groups that I’m involved with. But as of right now it’s not but I do know that it’s talked about quite often and I know that there are a few people actually trying to pull that together.

Talk about the relationship between wrapper systems being able to deliver a consistent force-to-load and a good system audit program.

Well if we are talking about audits and PM’s I can’t speak highly enough about it. PM regiments are the deciding factor if a company makes money or loses money, it’s just that simple. The problem here is that wrappers are among the forgotten machines in a production line. We are looked at as a cost and not really the moneymaker.

I’ll give you an example. If your favorite cookie dough company mixer goes down and the wrapper goes down at the exact same time which one do you think is going to get any kind of service or repair. The wrapper just gets a band-aid and some bailing wire and production goes on.

Many companies look at the wrappers as such a simple machine that it just is not going to take much to get it up and running even if they have to bypass say the pre-stretch function. They don’t comprehend how much money they’re losing just due to something as simple as film slippage. Maybe they have had to take their pre-stretch ratio down just to be able to run the film due to poor PM. This can cause the machine to use an extra half of a pallet per month and that comes directly off the bottom line.

We did a cost analysis for a major ultra-high production beverage company not long ago to see how much it would cost if that machine shut down for one hour during peak production. The cost was staggering. It was over $68,000 for one hour. When you put that kind of money in a production supervisor’s face it really takes them off guard.

System maintenance is a variable that can directly affect the amount of force being delivered by a wrapper. Explain its impact on force-to-load.

How important is PM maintenance? Very important. Think about the little device that a manufacturer may use on the carriage itself that is used to detect film demand in order to pay out the film correctly on a corner. Different manufacturers could use anywhere from a ten dollar sensor to a three hundred dollar sensor. If this device is failing or if it loses calibration then the corner compensation suffers.

This ultimately means that the machine’s operator may have to lower the film force setting on the panel to keep from breaking film and this does two things. This means that we are not applying the force-to-the load that we need to at a given amount of film on the load; it also means we are using much more film to do the same job and you wind up wasting film. So it is a huge importance to keep the machines properly PMed simply on a force-to-load basis.

Does film gauge and type - whether it’s a hi-tech or conventional stretch film – directly impact on force settings?

Absolutely they do. You know your cheaper, less compliant films can’t keep up with the same amount of force that a premium film can. They simply fail at higher force settings. Your better resin, your multiple ply films, your premium brands really have much more corner compliance, sharp edge compliance when using a high force. Your budget introductory type films just cannot compensate at the same force settings around those corners ultimately will fail based on high pull. So, yes it does have a huge effect.

If a company changes from one film manufacturer to another, is it probable that the force settings will also need to be changed in order to deliver the same on-pallet-force?

Yes it is. It is possible depending on the film’s memory capability. Remember it is stretch film so it does have a memory. If film A has high film memory then a lower force can be used while it’s wrapping because the pre-stretch is applying the film on the load and with better memory it’s going to tighten up over time. When that memory kicks in we would arrive at say force X. If film B has less memory capability or capacity then a higher wrapping force would be needed to arrive at X. And if the pallet has say sharp corners or whatever then you are not able to arrive at that same X setting.

So yes there will need to be changes made to the tension setting to compensate for different types of film to arrive at the same force setting. Absolutely.

It seems that both the wrapper and the film manufacturers could do more to promote greater information transparency in the marketplace. In light of all you have shared with us today, wouldn’t it be beneficial if these two industries formed a joint industry council to sponsor common standards and test protocols?

I couldn’t agree more. I really think that something like that needs to happen. I am sure that there are folks working on it. As a matter of fact I know a couple of really good folks that have some new websites up with some information. So the information is slowly getting out there. Whether it’s going to be a stretch wrap polymer manufacturer congress or not, I don’t know. I don’t know what the future is going hold but it certainly is needed. And I certainly look forward to seeing that in the future.
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Orion Packaging is an engineering driven manufacturer and worldwide distributor of automatic stretch wrapping machines and semiautomatic stretch wrapping equipment with facilities in Memphis TN and Alexandria MN. Orion leads the industry with an extensive product line of more than 25 models, including rotary turntable, rotary tower, and horizontal wrapping systems.

Bob Scoby
Technical Services Manager
Orion Packaging Systems
+1 800 333 6556
bscoby@orionpackaging.com
www.orionpackaging.com