Flow wrapping or flow packing, as it is also known, is one of the most frequently found packaging methods across a wide variety of product categories. This includes fresh produce, household goods, meat, dairy, bakery, stationery and even computer components where preservation, tamper evidence and brand display are key considerations.
Flow wrap packs are used by a range of companies too, from small enterprises for a wide variety of products where flexibility is important, right up to high volume large companies running dedicated lines, 24/7. Due to its popularity, many organisations often wonder what the choices are, how flow wrappers work, what materials are used and, most importantly, how they can benefit their business.
This article helps explain all the key consideration of flow wrapping and how it compares against other packaging options, including versus overwrapping.
Flow wrapping or flow packing is a packaging process where a product is placed either manually or robotically onto a horizontal conveyor that can push or just carry it along. It then goes to a wrapper using film or paper that seals it along the top or bottom side (depending on the machine used) and then neatly at both ends.
The great thing about flow wrapping, among other things, is the level of versatility offered for the organisation packing a variety of goods to save on time, cost, and unnecessary materials. For example, flow wrappers can handle products that are part packaged, like sandwiches in wraps, produce in punnets or even completely loose goods including greetings cards and books.
A horizontal machine is the most common type used but vertical machines are also available. Generally, it depends on the type of product being packed; vertical machines are used for sweets, some dry goods and salad leaves among other categories.
Flow wrapping of flow packing can be used on a wide range of products from food to medicines, along with household goods, to high value items where security is important like computer hard drives.
Some other methods, like stretch wrap, are constrained by the shape of manufactured items, flow wrapping is not.
Flow wrap machines make brand integrity cost effective, consistent, and flexible. Pre-printed film and paper, that is recycled and recyclable, are both options. When online printing and processes are built into a single pass, there is a great deal of value that can be added without significant cost.
With the addition of technology to ensure that the number of staff required to run and change a flow wrap machine is minimised, labour can be deployed elsewhere in the process. Additionally, it is now standard that machines are increasingly intuitive with multilingual HMI’s or Human-Machine Interfaces.
Couple this with the fact that diagnostics and updates can be added remotely, over-the-air, then a flow wrap machine can be described as truly low cost to run and maintain.
Flow wrapping delivers an airtight packaging outcome. With the removal of oxygen, it protects the product from contact with moisture and any form of airborne contamination including dust. Modified Atmosphere Packaging (MAP) or gas flushing is the practice of modifying the atmosphere inside packaging containing perishable foods. The aim of the process is to improve the shelf life and freshness.
It is quite harmless as the oxygen is removed as part of the packing process and replaced by, most commonly, nitrogen or carbon dioxide. Oxygen produces lipid oxidation reactions and causes high respiration rates and are to blame for shortened shelf life. The oxygen encourages the growth of aerobic spoilage, and the formation of other unwanted microorganisms may also potentially occur.
The MAP or gas flushing process lowers the volume of oxygen contained within the empty space or trapped within the product itself.
Horizontal flow wrapping machines can be seamlessly installed in production lines, enabling inter equipment communication and linking, for single point of control.
With technology on the rise, the use of robotics and automation to feed and pack flow wrapped products is becoming increasingly cost effective in any application.
Each of these packaging methods is suited to different applications. Flow wrapping provides an airtight seal, is a more economic use of packaging and can be adjusted easily. Uniquely, pre-printed, and fully recyclable packages are enabled. Overwrapping can be quite versatile as it fits snugly on punnets and packages, but it can bruise fresh produce, particularly mushrooms.
Flow wrappers create airtight seals on both ends of the item, forming a bag sealed at all open edges. The precise quantity of material required for the packaging is carefully defined making control of the cost very precise. Additionally, the tightness of the pack or bag can be controlled to improve the aesthetics.
Stretch wrapping is usually used with food and uses up to 20% more material than flow wrapping as it must overlap itself around the product or pack. While the unit cost difference is comparatively low, when it is grossed up over large production quantities, the overall packaging cost can be quite high. When efficiencies are factored in, the gap increases still further.
When a comparison is made between flow wrapping and stretch wrapping, flow wrapping is the better choice as a primary packaging material, particularly for fresh food, as it can pack at higher speeds and efficiencies, with increased hygiene and more consistent results. Most importantly, recyclable packaging can be achieved, through the use of pre-printed materials.
Flow wrapping solutions are used for the packaging of solid products and most certainly liquid items are not suitable for this process.
The most common applications of flow wrapping machines are biscuits, bakery items, chocolate bars, confectionery, fresh produce, household goods, meats, fish – both fresh and frozen, tea, coffee, and industrial goods. Flow wrapping is also used for packing items that have a hygiene requirement including face masks, medicines, and cosmetics.
The process of flow wrapping is achieved with a flow packing machine. This machinery carries out a pre-defined process to produce an end flow wrapped product, as follows.
The rate of flow wrapping varies significantly based on the machine, packaging type, pack size and additional considerations.
Some of the basic flow wrapping machines generally have working speeds of between 20 to 150 packs per minute. High-end, high-speed flow wrapping machines with speeds of 300 to 1500 packages per minute are usual for packing large quantities of products where time and cost are important.
The cost of a flow wrap machine can vary greatly depending on what needs to be packed and the material in question.
While the low-price tag of some machines may seem very attractive, the cost of ownership needs to be factored in. A flow wrap machine, for example, that requires a high manual labour input or that is unreliable, can suddenly become very expensive. Similarly, if service from the provider is poor and spare parts are unavailable or on long lead times, having a machine standing idle for even a few days can knock the edge off a low initial purchase price. It is wise to factor service and backup into the equation when making the purchase decision.
In all cases the flow wrap machine is usually the most important consideration as typically, there will be no back up flow wrapper, should an issue causing a stoppage occur.
Flow wrapping can use a wide choice of materials to wrap different products. A good quality flow wrap machine can be adjusted to accommodate a variety of products and materials as technology moves ahead.
Some paper-based wraps are made of plastic but with a coated layer of paper. Waxed paper packaging is often used in bread as it seals in freshness and is cost effective.
Great advances are being made with paper packaging that is from FSC (Forest Stewardship Council) accredited sources, have water-based ink, are made from recycled materials and are totally recyclable too.
Cold sealing film is suitable for heat-sensitive food items including chocolate bars and some bakery items. It uses adhesive instead of heat to seal the flow wrap pack.
Heat sealing uses a several film or papers. The seals on the surfaces are created by applying heat and pressure, resulting in a sealed flow wrap bag. This is a very low-cost option for creating flow wrappers to package most products. Suppliers can advise on the differences in films and the optimal temperature for the type of film used for flow wrapping.
Laminated film wrapping uses multiple layers of different packaging materials for their enhanced properties. Usually, laminated layers are more robust, have improved wear and tear resistance, are impermeable and generally have a better visual appearance.
Laminate film is normally made from materials such as aluminium foil, polyethylene/polythene (PE) or polyethylene terephthalate/polyester (PET). Laminated film provides more enhanced properties for products, than mono flow wrap materials. However, laminate films are made using different types of materials, so they are currently the most difficult to recycle.
Mono film consist of multiple layers of the same material which makes them a great deal easier to recycle as separation is not required.
Yes! Through the use of differing blends, of the same polymer, into multi layers, both cost effectiveness and efficiencies can be achieved in flow wrapping.
The selection of the right material is more efficient, uses less energy in the recycling process and, in turn, creates higher-quality recycled products.