How much does stretch wrap stretch? Is more better?

With competitive price and timely delivery, SMART WASP sincerely hope to be your supplier and partner.

The simple answer is that quality machine stretch film typically stretches 3x or more.

The right answer is&#;.it depends on the stretch film, the machine and most importantly, your product, loads and goals.

Here&#;s the full answer

Confusing stretch with tight & secure

Sometimes you&#;ll hear people refer to the plastic that they wrap around pallets as shrink film. You know what they mean of course, but the proper name is stretch film for a reason.

Modern stretch film formulations are made to stretch &#; but maybe not for the reason, or to the extent that you imagine.

When Pat Lancaster invented the first stretch wrapper in he used a 60&#; roll of plastic film designed for use in dry cleaning facilities. The idea was to lay the film against the rotating pallet and rely on a core brake to slow the film enough that it stretch a bit and compressed the load as a result. T

hat invention rapidly evolved to the spiral wrap so popular today. The polyethylene stretch film we rely on now rapidly followed.

That&#;s essentially the same process repeated thousands of times each day as workers hand wrap loads with 12 & 18&#; wide rolls of hand stretch film.

And most importantly, load security is determined by containment force &#; or wrap force X film layers. It turns out that stretching isn&#;t a factor.

Dollars & cents

Stretching the film (or, more precisely, pre-stretching the film before it leaves the film delivery system) is an economy measure. Pre-stretching film is what made stretch wrapping affordable and opened up the stretch wrapping and stretch film industries that we know today.

Pre-stretching film saves money.

Common pre-stretch percentages (which are typically determined by a set of gears in a wrappers pre-stretch carriage) range from 150-300%. That means that every linear foot of film coming off a roll represents 2.5 to 4 feet of film on the load. 

That&#;s some pretty compelling savings! In fact, most companies buy their first pallet wrapper with a simple film savings calculation.

More is better, right?

To a point. There are more factors to consider here. 

Film attributes include:

• gauge
• formulation
• puncture & tear resistance
• roll length
• price/lb

Load attributes include:

• weight
• load configuration (like a cube or uneven)
• need to lock load to pallet
• inboard or outboard (product is smaller or larger than the pallet respectively)
• containment force which is a product of wrap force (tension) and revolutions

Best practices for determining the optimal film usage include:

1. Establish standards for the load: containment force value, load-to-pallet bond, no long or dragging film tails. They maximize the probability of safe shipment.
2. Determine settings: These are the film choices (quality, gauge and price) and machine adjustments (pre-stretch percentage, wrap force, top and bottom wrap counts, film delivery system speed up and down, film overlap, etc.) that ensure the standards are achieved.
3. Establish a feedback loop that ensures the standards are maintained,

The reality is that thinner film doesn&#;t always result in a net film savings! Decreases in film thickness result in a loss of wrap force because of increased film breaks. Because it&#;s notoriously hard and time consuming to find the root causes of film breaks, operators frequently get rid of them simply by decreasing the wrap force until they stop. Consequently, more film layers must be applied to recover and maintain containment force that&#;s lost and film consumption increases.

Every load does not have an optimal wrap pattern. It does, however, have an optimal containment force. If my load needs 10 pounds of containment force, I can get it by using a thin film and applying lots of layers or I can use a thick film and apply fewer layers &#; the resulting containment force can be the same but the wrap patterns and throughput rates can differ significantly.

Film spec is not the load spec

Most machine films are engineered today to comfortable pre-stretch to 300%. If you stretch further you may experience more breaks &#; particularly on corners of loads where tension increases with most film delivery systems.

Technology will let you stretch your budget figuratively and literally. The risk is that savings achieved through down gauging and extreme pre-stretch may be lost to the damaged product which can result when containment force is adversely impacted by related film changes.

The real question companies need to answer is &#;What containment force is required to safely ship my load?&#; From there, local experts familiar with films and machines can design the right combination and establish parameters to ensure loads are properly wrapped.

The short answer to how much does stretch wrap stretch? Stretch film will stretch as much as your machine is designed to stretch it. 300% is not unusual &#; but may not be the best answer. Stretching the film budget in one direction, without considering other impacts, can cost far more in product damage than is saved on film. Remember, there is balance between thick stretch films applied with high wrap force and few film layers versus thin films applied with low wrap force and more film layers.

Wondering how much pre-stretching your stretch film could save you?

Good question. It&#;s one of the classic justifications for a new stretch wrapper. We&#;ve got a free calculator available for download that you can use to estimate savings. Grab your copy here.

And don&#;t forget other considerations. In high speed wrapping applications, overstretching film can lead to frustrating and costly down-time through film breaks. This is especially common on irregular loads (like distribution centers) and corners of loads if the machine doesn&#;t adjust the way it feeds film.

Click here to see the Film Cost Savings Calculator.

You may be interested in these related posts:

FilmCostCalc

This post was published on June 28, and updated on November 9, .

How much does stretch wrapping stretch? Is more better? Depends on the stretch film, the machine and most importantly, your product, loads and goals.

Thin plastic film used for sealing food

This article is about a plastic layer used for short-term preservation of domestic foods. For a plastic wrap often used in bulk packaging, see Shrink wrap and Stretch wrap

Plastic wrap, cling film, Saran wrap, cling wrap, Glad wrap or food wrap is a thin plastic film typically used for sealing food items in containers to keep them fresh over a longer period of time. Plastic wrap, typically sold on rolls in boxes with a cutting edge, clings to many smooth surfaces and can thus remain tight over the opening of a container without adhesive. Common plastic wrap is roughly 0. inches (12.7 μm) thick.[1][2] The trend has been to produce thinner plastic wrap, particularly for household use (where very little stretch is needed), so now the majority of brands on shelves around the world are 8, 9 or 10 μm thick.

Materials used

Plastic wrap was initially[when?] created from polyvinyl chloride (PVC), which remains the most common component globally. PVC has an acceptably-low permeability to water vapor and oxygen,[3] helping to preserve the freshness of food. There are concerns about the transfer of plasticizers from PVC into food.[citation needed] Pliofilm was made of various kinds of rubber chloride. Used in the middle of the 20th century, it could be heat-sealed.[4]

A common, cheaper alternative to PVC is low-density polyethylene (LDPE). It is less adhesive than PVC, but this can be remedied by adding linear low-density polyethylene (LLDPE), which also increases the film's tensile strength.[5]

In the US and Japan, plastic wrap is sometimes produced using polyvinylidene chloride (PVdC), though some brands, such as Saran wrap, have switched to other formulations due to environmental concerns.[6]

Food use

Purpose

The most important role plastic wrap plays in food packaging is protection and preservation. Plastic wrap can prevent food from perishing, extend its shelf-life, and maintain the quality of food. Plastic wrap generally provides protection for food from three aspects: chemical (gases, moisture, and light), biological (microorganisms, insects and animals), and physical (mechanical damage). In addition to food protection and preservation, plastic wrap can also reduce food waste, tag food information, ease the distribution processes, and increase product visibility and microwavability.[7]

In the s, Snappies cling-film was advertised in the UK by Katie Boyle.[8]

Health concern

Plastic materials are widely used in the food industry due to their low price and convenience; however, there has been an increased health concern because of the possibility of releasing undesirable chemicals from plastic materials into food products. Plastic packages are made of various materials such as polyethylene, low-density polyethylene, etc. Additives, including lubricants, plasticizers, UV-absorbers, colorants, and antioxidants, are added into plastic materials in order to improve the quality and properties of the plastics. Besides, plastic materials are often coated and printed in the final processes, in which inks and varnishes are used. Although the barrier properties of the plastic packages provide protection of foods from external contaminations, the additives and coating materials in the plastic packages are able to penetrate into foods and cause health-related issues.[9]

"It is true that substances used to make plastics can leach into food," says Edward Machuga, Ph.D., a consumer safety officer in the FDA's Center for Food Safety and Applied Nutrition. &#;But as part of the approval process, the FDA considers the amount of a substance expected to migrate into food and the toxicological concerns about the particular chemical.&#; A couple of cases have caught media attention in recent years. One case is in regard to diethylhexyl adipate (DEHA). DEHA is a plasticizer, a substance added to some plastics in order to make them flexible. There are public concerns about DEHA exposure while consuming food with plastic wraps. There are potentials of exposure to DEHA; however, the levels of the exposure are much lower than the no toxic effect levels in animal studies. Another case is in regard to the dioxins, labeled as "likely human carcinogen" by the Environmental Protection Agency. The public has been misled by the claims that plastics contain dioxins [citation needed], while Machuga stated that no evidence that shows plastic containers or films contain dioxins was seen by the FDA [citation needed]. According to writing in FDA Consumer Magazine as of November , when used properly the use of plastic wrap in food preparation does not pose danger to human health.[10]

Environmental concerns

The accumulation of plastic debris on the Earth threatens both wildlife and the environment. Plastic debris might choke or trap wildlife, and it could also penetrate toxic compounds into ecosystems. This land-originated problem has become a problem in ocean ecosystem as well since streams and rivers which are close to the land have carried the plastic debris into the coast, and currents transfer it to everywhere in the ocean. Plastic debris is a potential danger to all forms of aquatic life. Some marine species, like sea turtles, take plastic as prey items by mistake. Besides, some species might even pick up plastics and feed their offspring, which cause huge problems on growth and even cause mortality. Toxic compounds in plastics can disrupt hormone regulation in the cells of organisms, which can lead to alteration of animals&#; mating behavior, reproductive ability, and even cause the development of tumors. Plastic debris could be a big threat to lives in the ocean.[11]

A study shows that using recycled plastic materials can reduce the environmental impacts significantly as a result of minimizing exploration, mining and transportation of natural gas and oil. One of the possible ways to increase the recycling rate is adding fibrous reinforcement into plastics. The environmental impact has been assessed using the life cycle assessment method. The results showed that plastics with fibrous reinforcement added can sharply reduce resource usage and global warming in civil applications.[12]

Medical use

See also

References

• Cling film at Wikimedia Commons

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