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Tell me what you bag and I'll tell you what to choose - BAG TYPES

If you’re familiar with the bagging industry you would certainly know there are several bag types on the market. Of course your supplier will suggest the best option according to your needs, but do you have the notions to make informed decisions by yourself?
If not (or if you’re not sure), then you’re in the right place: we’re breaking down the most popular bag types together with a smart guide of typical use, main features, advantages and disadvantages. Ready?


1. FILM BAGS

These bags usually consist of a polyethylene (PE) film, a very resistant – and also inexpensive – plastic material that runs in the filling machine and is closed thanks to a heat-sealing mechanism. The typical application is for bagging products such as: salt, granular fertilizer and plastic pellets, but it’s to say that this material can also be used to bag other goods depending on the client’s preferences. You can choose between two categories of film bags: flat film and tubular film.

a. Flat film – VFFS [Vertical Form, Fill, Seal] and HFFS [Horizontal Form, Fill, Seal] bagging machines

This system uses a reel of flat foil film that is wrapped around the filling tube and closed thanks to an edge sealer. The main advantages of this bag type are lower costs and a reasonable filling speed. This sounds pretty good, so why aren’t these bags so popular ? Well, they come with a couple of significant disadvantages: changing the film is time consuming and the vertical sealing on the back makes the bag very fragile (in other words, if it drops it will split). For this reason, this bagging method is usually indicated for weights up to 20/25kg.

b. Tubular film - TFFS [Tubular Form, Fill, Seal] bagging machines

These bags make up for the flat film’s weakest point – fragility – and therefore don’t have the back sealing; in this case the film is tubular, i.e. opened only on the short sides. Application and sealing are the same as flat film bags, with the difference that the tubular reel is more resistant – and the machine much more expensive – than the flat one. Another difference among the two categories is speed: TFFS bagging machines can reach a higher speed than VFFS ones.

 

2. VALVE BAGS

These bags are typically made of paper and are almost completely closed with just a small opening on the top, the so-called “valve”. They have been the leading trend in the market for many years because of their availability and their big advantages: they allow a high-speed filling rate and don’t need external closing machinery, since it’s the interior pressure of the bag that closes the valve. What’s happening now? The trend is changing towards open mouth bags because of the main drawback of valve ones: cleanliness and safety. Especially if you handle food, this bagging method turns out to be unsafe because it doesn’t allow a proper sealing; that’s why the usual application of these bags is rather concrete, construction materials or fine chemicals.
 

3. OPEN MOUTH BAGS

Open mouth bags are closed on the lengthwise side and on the bottom, leaving the top side open. This is the most versatile bag type, since it’s available in different sizes and materials and is suitable for several closing systems (e.g. sewing, gluing, sealing and so on), which makes the sealing process safer and more reliable. If these bags are so flexible, why aren’t they the only bag type on the market? Well, of course you need to bear with a couple of weak points: firstly, you’ll need an external sealing mechanism to close your bags, and this implies costs; and, secondly, you’ll need to accept a slower production rate (up to 25 bags per minute with granular, heavy, no-dusty products and 20/21 bags per minute for cereal flour products). But if you take into account the advantages of this bag type, you’ll notice its significant benefits: the bag is easier to open, handle and close, it’s re-sealable, there’s a better product distribution, and, last but not least, the bagging station can handle different kinds of bag.

What does the market say?

Market statistics support this: even though valve bags allow saving in equipment and maintenance costs, open mouth ones are less expensive and, if purchased in high volumes, they can offset the equipment expenses, together with the benefit of being leak proof and more hygienic. That’s why a lot of companies chose to go for this kind of bag, and we belong to this group: providing a machine that deals with open mouth bags is like providing a white canvas that can be adapted to the customers’ needs, with the guarantee of high safety standards. We actually have a complete range of bagging lines that fulfills the market requests from 1 to 25 bags/min, with dedicated execution for specific products; what’s more, our proved empty bags handling system is designed to handle every bag material, including non-laminated PP woven.

So, to sum up, what should you choose? Well, the answer depends on different factors such as: product properties, company needs and goals, safety requirements and costs. There isn’t a unique solution, but the trend is generally leaning on open-mouth bags because of their reliability and versatility and this turns out to be particularly adequate for the food and agro-industrial sector.


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