Economical and efficient packaging solutions using film-formed bags, along with the compact and space-saving nature of VFFS machines, have made them widely applicable across various industries.
Do you want to understand how Vertical Form Filling Machines work? Would you like to learn about the functions and features of the components of VFFS Machines? In this article I will introduce you to the packaging process of the Vertical Form Filling Machines, from the rolled film to the finished bag.
The Vertical Form Fill and Seal Machine, also known as a collar type filling and sealing packaging machine, is suitable for packaging various materials such as granules, powders, liquids, and pastes in pouches. The machine forms rolls of plastic film into bags, then measures the predetermined weight or volume of the product using a metering system before sealing the bag, creating a complete package.
Roll film is unwound through an external film release device and pulled by a servo motor conveyor belt.
The coder is suitable for plastic film, PP, OPP, paper bags, labels, etc., integrated into VFFS machines to print batch numbers, production dates, and expiration dates on the film as it passes through the machine.
#1 Set the horizontal and vertical sealing bars, as well as the date coder, to the required temperature to ensure that the ink adheres correctly to the packaging material.
#2 Synchronize the printing speed of the coder with the packaging speed of the machine.
Set the target bag length through the control panel, adjust the servo motor drive speed to pull the film. When setting the bag length on a VFFS machine, the following factors need to be considered:
Film Positioning has two options selectable on the touch screen: color mark length (photo-electric eye) and encoder length.
Color mark length (photo-electric eye):
Usually, printed films have color marks on them. The photo-electric eye detects these color marks on the film. The bag length is determined by the distance between color marks. The cutting position of the film can be adjusted based on the color mark points to avoid cutting into the printed design.
Encoder length:
Choosing encoder length allows direct modification of the packaging length on the screen. The length is detected as it scrolls, immediately changing the size of the bag produced (changing the bag width requires changing the forming unit). The length of the cut film is correct, but the cutting position cannot be adjusted, which may result in cutting into the printed design of the film.
When the bag needs to stretch the film twice, set the second stretch length here (total stretch length = first stretch length + second stretch length).
There is frictional resistance between the film and the machine, which affects the actual packaging bag length. (Thicker films have greater resistance).
If the packaging bag length does not reach the set accurate length, adjust the correction data until the desired true length is achieved.
VFFS packaging machines are equipped with lifting systems and measuring systems for material lifting and weighing.
Transports the packaged material from the ground to the weighing hopper above the packaging machine. It can be divided into granular, powder, and liquid/paste types.
Granular material: Z-type elevator, Large slanting elevator, single-bucket elevator, bucket elevator
Powder material: screw elevator, vacuum elevator
The material is lifted to the hopper and measured according to the set packaging weight.
The most commonly used measuring systems are:
Combination scales (for weighing granular, flake, block, and strip materials, including candies, cookies, coffee beans, chips, nuts, frozen foods, vegetables, etc., with fast speed and accurate measurement).
Screw metering machines (for powders such as flour, coffee powder, protein powder, additives, etc.).
2-head/4-head/6-head linear scales (for fine granules or coarse powders, rice, sugar, salt, laundry detergent, coffee powder, with a wider measurement range than combination scales, acceptable accuracy, slightly slower speed than combination scales, tailored to different materials).
For liquids or pastes, piston filling machines are used (or servo-controlled rotary pumps for high accuracy, wide range, fast speed, but higher price).
After the film is unwound, it is stretched and cut according to the set bag length, and then formed into bags using different forming collar devices. Operators can change the width of the packaging bags by replacing different forming devices.
The edges of the film overlap vertically and are heat-sealed together to form the back seal of the packaging bag. Different back seal forms are available for selection through the settings of VFFS machines.
The dosing feeding system delivers materials into the packaging bag forming area. After the bag is filled, the sealing clamp seals the top of the bag, creating a top seal for one bag and a bottom seal for the next bag.
Here are the characteristics of bag sealing:
The cutting device of the machine separates the sealed continuous packaging bags, and the cut packaging bags are transported via a conveyor belt to downstream equipment such as pallets, checkweighers, metal detectors, boxing equipment, etc.
Companies that package liquid products often want two things in their automated packing system: A clean packaging process and the ability to wash down their equipment.
Luckily, modern packaging automation technologies fulfill those liquid packaging requirements...plus much more.
I'm Scott Miller, Viking Masek's VP of Product & Technology, and today I am taking you on a walkthrough of our most unique liquid packaging machine: The VFFS Liquid Sigma.
Kinsun are exported all over the world and different industries with quality first. Our belief is to provide our customers with more and better high value-added products. Let's create a better future together.
The Liquid Sigma is a continuous motion VFFS machine, meaning the packaging film moves continuously without stopping to receive its vertical seal. This result is faster packaging speeds.
Design
The design of the Liquid Sigma is stainless steel, IP66 washdown. This IP Rating means the machine's enclosures are dust-tight and can be safely cleaned with strong jets of water. The only exception to this design is the jaw carriers, constructed from aluminum for proper weight distribution (stainless steel is too heavy).
Controls
The control system for the machine is an Allen Bradley Panel View coupled to a Compac Logix PLC and Kinetics servo drives.
Electrical components
Usually mounted directly to the side of the machine, the electrical cabinet is instead remote mounted on the Liquid Sigma. It can be mounted in a different location, out of the way of the washdown environment. One hundred feet of cable attach the remote cabinet to the machine which allows for flexibility of placement. Two junction boxes on the machine where the cabinet would have been mounted act as the termination points for all electrical components.
With the intro out of the way, let's dive right into our walkthrough, starting at the top of the machine:
A VFFS liquid packaging process usually begins with the liquid product in a hopper. This hopper can be heated if the product must be packaged at a higher temperature to reduce its viscosity.
A liquid piston pump will draw the liquid product to the top of the machine where a lance will deposit discrete volumes of product into the bag through the hollow center of the forming tube.
A wide, flat roll of film is threaded over various rollers through the machine and then threaded over a forming tube assembly which brings the vertical sides of the bag together to begin forming its shape.
The film is transported through the machine by vacuum pull belts. These belts use vacuum suction to grip the film and transport it through the body of the machine.
Vacuum pull belts come as standard on the Liquid Sigma. The advantages of vacuum pull belts include less wear and the fact that the film will not be squeezed tightly against the forming tube and instead will have a 1mm gap. This minimizes film bunching or slipping issues that may arise when using regular friction pull belts.
The Liquid Sigma uses a continuously moving heated band-type vertical seal assembly. This allows for uninterrupted seal creation on continuous motion machines. The band seal does not come in direct, constant contact with the film. Rather, it is set to a fixed gap so it does not squeeze the film against the heated block of the seal assembly.
As the film passes by the heated block in the vertical seal assembly, it bonds the layers of film together to create a strong vertical bag seal.
Using a lance that transports the liquid product through the hollow center of the forming tube, the liquid product is deposited into the bag in discrete volumes.
The Liquid Sigma shown in the video above is custom-designed with special components that detect the volume or the fill heights of the liquid in the forming tube itself. As the film moves in a continuous motion, the liquid level within the forming tube area goes from the top sensor to the bottom sensor and stays within that range as the bags are filling.
Typically the bags fill in 1/2 gallon or 1 gallon fills, usually hot fills. However, we have done projects with product temperatures as low as 34° F and as high as 195° F.
The squeeze roll assembly is designed to provide an airless fill. This means each bag will have zero residual air inside it after sealing.
The squeeze roll assembly opens and closes with every cycle while the film moves continuously. The squeeze rollers are programmed to 'know' that they must close at a specific time in order to provide the pre-specified volume of liquid into the bag.
The design premise behind the squeeze rollers is influenced by the durometer of the squeeze roll material. It is available in a couple of different durometers that are directly related to the desired product fill, the product, and how hard or soft the rollers must be.
A set of heated jaws come together to bond the layers of film together to create a strong horizontal seal. The seal of the bottom of the bag and the top of the next bag are created at the same time.
The jaw design on the Liquid Sigma is unique, configured in such a way that it can seal through any residual liquid that is left on the inside of the film. This means each bag will receive a strong seal and you won't have to worry about messy, leaky bags.
At this point, the finished bag is cut and discharged from the machine. It can either be deposited into a receptacle or dropped directly onto a conveyor to transport it to downstream equipment like checkweighers, carton packing, or case packing.
Film carriage
The film carriage on the Liquid Sigma is 100% stainless steel, allowing for 100% washdown. In most cases, customers are cleaning with caustic cleaning foam and rinsing with a hot rinse. Stainless steel construction means you can aggressively wash down those components and not have corrosion issues or breakdown of metals.
Powered film unwind
The film unwind has a surface assist. Films for liquid products tend to be a little more slippery and the surface assist provides a positive unwind and helps the film move through the system easily.
Extra film spindle
Many clients opt to purchase an extra film spindle so they can have an additional roll ready when it comes time to change rolls. This saves time during splice cycles.
Film splice table
Above the roll of film, you will see a splice table, which is used to join the end of a spent roll of film to a new roll. This will automatically draw the new roll of film through the machine without having to manually re-thread it.
Printer
Clients can opt to add a printer to their Liquid Sigma for date coding purposes. Located directly in the film path, the printer is usually not fully washdown, so care should be taken to remove or protect it during washing cycles. Enclosures are available to protect key printer components during washing.
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