Equipment feature: A case of vertigo?

Form, fill and seal machines can be horizontal or vertical. But what is the difference? Is one better than the other? And how do the pack styles produced differ? When talking about the differences between vertical and horizontal form fill seal (FFS) machines it’s important to clarify what is meant by these terms.

Broadly speaking, the term vertical FFS refers to equipment that produces pillow packs. From a roll of pre-printed, heat-sealable film and with the help of a forming shoulder, the vertical FFS forms a tube of film. This is then sealed vertically, by means of a heated back seal bar. A set of jaws then creates a cross seal, which becomes the seal at the top of the bag below and the bottom seal of the bag being made, and a knife located within the jaws simultaneously cuts through the web to make the tube into a bag of the desired length. While the bag is being formed, product is gravity fed into it.

However, there are variations on this theme. Vertical sachet makers, for example, produce three- and four-side seal sachets, usually across several lanes. The machines use vertical sealing plates to create side seals. Sealing jaws then seal the tops of the filled pouches while simultaneously sealing the bottoms of the next pouches, and knives separate the packs.

Then there is the stick pack maker, which is essentially a mini pillow pack machine for creating condiment portion packs. These tend to be multi-lane machines so you get exceptionally high speeds, but the main reason companies use stick packs is that they use 40% less material than sachets.

Two technologies
The term horizontal FFS confusingly covers two very different configurations: flow wrappers and pouch/sachet makers. The flow wrapper is similar to the vertical pillow pack machine, but the product is presented to the equipment in a different way.

“Vertical FFS has gravity on its side, horizontal doesn’t,” says Steve Holt of Record Packaging, which sells both types of equipment. “This means product simply drops into the bag on a vertical machine. With horizontal kit it needs to be carried, pushed or pulled into the bag. The film also needs to be pulled using back seal rollers, whereas with vertical it can be moved using belts.”

Horizontal flow wrappers can be either top web for standard applications or bottom web for irregular, sticky, fragile or difficult to control products. The main difference between a horizontal pouch/sachet maker and a flow wrapper is that on a pouch maker the packs are individually formed and sealed. A length of film is folded along a line in the direction of transport. The sides of the pouch are then formed by cross-sealing the film. The folded and sealed sheet is then cut along the line of sealing into individual pouches. The pouches are filled, usually on a carousel, and sealed.

Decisions about what type of FFS system a packer or producer should choose depend on what pack presentation they are looking to achieve and what product they are packing. The basic rule of thumb is that free-flowing products such as powders, crisps, pasta and peas are best packaged on a VFFS, whereas collated, assembled or trayed products like biscuits, bread rolls or medical devices are best dealt with by a horizontal flow wrapper.

“Horizontal technology is ideally suited to regular-shaped products for high-speed wrapping, such as biscuits and chocolate bars, or, conversely, awkwardly shaped or difficult-to-handle products like individual vegetables, or simple collations of items like tomatoes, fruit, cheese and meats,” says Derek Paterson, managing director of Ulma Packaging, which has just launched a new entry-level VFFS system. “Vertical is much more suited to bulk loose items such as salad leaves, powders, granulates, liquids and pastes.”

Stronger seals
Mike Lindsay, sales manager of Integrapak, which distributes Schwarze VFFS machinery and Volpak pouch-making equipment in the UK, agrees it is possible to use a VFFS for liquids, but says most liquids would be better filled on a horizontal pouch maker.

“A liquid pack needs a high level of seal integrity, and it is very difficult to get that when you’re filling immediately after sealing. You can only really achieve a strong enough seal on a vertical machine by going to ultrasonic sealing, but even then you’re limited in terms of capacity – if the pack is any bigger than about 250ml it won’t survive a drop test. On a horizontal pouch maker, because the packs are individually formed, there is time to cool the seals, so they are reinforced prior to filling.”

Lindsay says retort applications are another area where the seal integrity provided by horizontal pouch makers makes it the technology of choice. “When you cook a product in a pouch – which is what you do in a retort – you’re subjecting it to very high pressure, and generally VFFS machines don’t offer that level of integrity,” he says. Pouch makers also enable several different ingredients to be filled into the same pouch, which has advantages for products like dried soup.

Horizontal pouches have also enjoyed an upsurge in popularity in recent years because they denote a premium positioning. “There are high value products which have moved to pouch machines for marketing and shelf presentation reasons,” says Mark Lozano, national sales manager with TNA, whose speciality is high speed vertical baggers.

In terms of the packaging styles that can be produced on each type of machine, VFFS machines offer greater flexibility than horizontal flow wrappers, according to Ulma’s Paterson: “Verticals can be more inventive and offer much more scope in terms of pack style and design. These systems are capable of producing virtually any size or shape, including pillow bags, bags with a side gusset, stand-up flat bottom bags with various seal types, bags with three- or four-sided seals, true vacuum packs and bags with ultrasonic sealing. Vertical machines can also punch a handle into the top of the bag. Horizontals produce pillow, zipper and gusseted bags.”

TNA’s Lozano adds: “Both VFFS and flow wrappers can produce pillow-style bags; if you look at a tray of cookies and examine the bag, it is primarily the same as a bag of potato chips. However, vertical machines have been developed to provide a variety of bags: lock bottom, corner sealed (quattro) and stand-up pouches (canoe/doyen). To my knowledge, these additional configurations are not available on horizontal flow wrap machines.”

Horizontal pouch makers, meanwhile, offer even greater versatility. Effytec’s range of pouch makers, which are distributed in the UK by PAP Services, can create three- and four-side seal sachets for pharmaceutical products, gusseted pouches for dried soups, doypacks with a round base (for liquids) or square (for confectionery), doypack pouches with a corner valve, top valve or front valve for liquids or pastes and doypack or flat pouches with reclosable zippers.

However, the high seal integrity, premium look and flexibility come at a price, according to TNA’s Lozano. “Pouch machines can handle all of the vertical applications but are wasteful of material, are less efficient and eat up more space than a VFFS. They are physically larger, carry out more operations per pack, use more material and require more fillers to maintain a viable production speed. Plus they are more expensive.”

Flow wrappers and VFFS are comparable in price, but differ in speed and size – horizontal flow wrappers tend to be larger and faster than VFFS machines, which are usually intermittent.

“Vertical systems are more compact and offer better flexibility, but are generally slower. In addition, these machines provide quick changeover between many different packaging formats. Horizontal is favoured for higher-speed applications but could be an expensive option for low-speed bagging,” says Paterson.

So there is a form, fill and seal machine to suit every application. And the choice between horizontal and vertical can come down to how you want the end result to look and how fast you want it filled as much as the product going inside

Pharmaceutical sachet makers
Sachet makers for powdered pharmaceutical products can be horizontal or vertical. Vertical sachet makers are usually multi-lane machines, producing several sachets simultaneously, whereas horizontal sachet makers work on a single track – vertical has the edge where speed is concerned.

“The vertical machine produces more packs per minute and it is more suited to being integrated with the cartoner, with an intermediary count unit. The horizontal version also allows for this type of configuration, but the overall size of the line is greater,” explains Marchesini’s Norman Nanetti, product manager, sachet machines.

Marchesini has recently upgraded its MS235 vertical sachet FFS by incorporating a new dosing unit.

“To guarantee a perfect dose in every sachet each dosing screw feeder has been fitted with a motor-driven secondary pre-screw feeder device which feeds the product constantly into each dosing channel,” explains Nanetti.

An independent brushless motor drives the secondary screw feeder unit and dispenses with mixers around the dosing unit. The dosing system is also set up for weight checking and feedback on each lane.

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