Paper Folding Machines
In print centers small and large there has always been a demand for a wide variety of paperweights to be folded, with a wide rage range of volumes. A smaller digital print shop now has clients demanding short-run full-color work being requested on heavier stocks along with more traditional flyers and brochure text weight jobs. These stocks have characteristics that require more advanced folding machinery to finish the work without cracking or curling. At the same time, they still get the orders arriving for longer run direct mail text weight work needing to be folded quickly and efficiently.
When a printer is shopping for folding machinery, he/she has two categories of folders to pick from: the conventional buckle plate folder and the more recently designed knife folding systems with integrated creasing capabilities. With prices that range from $1,000 up to $45,000, it is important to understand the strengths and weaknesses each of these designs will bring to your printing facility.
Before jumping to the paper folding machine mechanisms lets first clarify the types of paper stocks that are used in today's print industry.
These sheets are thin, flexible sheets similar to your desktop office printer paper, or paper used for flyers, theses text weight papers are available in both coated and uncoated finishes.
Card stock or also known as cover stock sheets are thicker, and have more body to them, giving them much greater rigidity. This stock is used in applications like business cards, greeting cards, or covers for perfect bound books. This stock much like the text weight is available in both coated and uncoated.
Buckle Plate Folders
Buckle folders are the more common type of folder found in print shops. To fold paper they use a set of guides and plates with a backstop which is set to a dimension and the paper will buckle when it strikes it and they move in and out of the plate to create the fold (see illustration below).
When looking at buckle plate folders that have been designed for the digital printer, the options are available in a wide range of automation and offered one of two types of feeding systems: Friction feed or Air / Suction feed. Entry-level designs are tabletop and offer Friction feeding, like the MBM 208J, up to the more automated Duplo DF 990A, Formax 382X, or MBM 408A the feeding system is the most important feature to discuss and understand how it works and to understand their limitations.
Friction feed Paper Folders
The friction feed folder has a feeding mechanism that has one to three rollers across a bar, with a tab below the center roller. These rollers spin and the sheet of paper is to be pulled into the unit. The tab on the bottom is to hold back the second sheet of paper from entering the folder at the same time as the first, preventing double sheet feeding. Once the sheet of paper enters the folder the fold rollers take over moving the paper through the process of being folded.
For a video demonstration click HERE
Limitations of friction feed folders:
Coated Gloss Stocks
Much like a car tire on ice, friction feed folders struggle with feeding coated papers with any consistency. At times you may be able to have the folder on a consistent run with coated paper but, certainly, there are an equal amount of times when the unit will struggle to feed even a single page of coated paper
Digitally printed work is printed with heat and static fusing process. After printing is complete the pile of paper still maintains is static charge and separating sheets can be difficult using a friction feed process. Air feeding better separates the sheets before feeding them into the folding unit.
Air/Suction feed Paper Folders
With an understanding of the friction feed systems limitations, printers that find themselves running a lot of coated stock that has been digitally printed with an abundance of static from the fusing process the Air Fed systems available on models such as the tabletop MBM 1800S, or the Duplo DF 1300 A, or the Morgana Major offer a perfect solution for a large production facility or a storefront digital print shop.
There are two concepts to be aware of when considering adding an air feed folder to your shop– Top fed system and Bottom fed systems.
Top Fed Paper Folder System
Top feed systems give the operator a push the green button solution and enable you to load your job (generally up to 4-5” of stock) into the feeder tray and walk away. No need to have an operator stand and feed a machine. While the operating speed on top-fed systems may be slower the fact that an operator can run this along with other machines in your facility makes it a good boost to productivity.
- Apply air with a fan to separate the top pages from on another sheet of paper is sucked to a series of tractor belts with a suction fan, and these belts transport the sheet into the fold rollers
- The caliper system is similar, however, the operator is able to increase or decrease a gap so that only one sheet of paper can travel into the unit at one time.
For a video demonstration please click HERE
Bottom Fed Paper Folder System
Bottom fed design which can be found on the popular Morgana Major, or another popular choice that is Morgana Docufold Pro offers a very quick operating speed and with the ability to continuously load onto the pile allows for non-stop production. A great saving of time especially in busy commercial shops, or shops running longer runs of work feeding from the bottom of the stack allows loading on the run for non-stop production.
Specific to Morgana, their PosiFeed feed system has been around for years, it was originally developed for their high-speed rotary numbering machine the Morgana FSN which has the ability to feed some of the most troublesome stocks.
- Air is applied through the side of the pile of stock for separation
- The feeding drum stops as the vacuum pulls the sheet down before the drum begins to feed.
- The feed drum then advance the under the caliper system which the operator can adjust based on the paper stock running into the fold rollers
For a video demonstration please click HERE
Whether you select an air fed system, or a friction fed system these smaller buckle plate folders both share a common limitation, which is the ability to stop cracking of toner and paper, as well as fold anything heavier than 80-100lb stocks. Although buckle folders are fast, simple, efficient, and have small folding tolerances, they are not suitable for substrate of very low (<40g/m²) or very heavy paper grammage (>120g/m²). This is where the cross over happens and knife folders with integrated creasing can become a valuable asset to a print shop looking to create high-quality output with ease of use.
Folding card stock is traditionally a more difficult process than folding standard text weight stock.
The three major problems experienced when folding card stock are:
- Curl of the paper when folded: Imagine a sheet of paper being wrapped tightly around a pencil, this is essentially what you find when trying to fold card paper around rollers in a traditional buckle plate folder. If you are able to pass the work through the traditional rollers of the unit it will have a distinct bend to it.
- Cracking: While not new to digital printing specifically, cracking on heavyweight paper has long been an issue for printers. When we fold a sheet of printed card stock we notice that along the spine the toner or ink will split and we will be able to see the white paper beneath ruining all the hard design work put into the original plan. See our article about cracking for more information.
- Marking: When we attempt to feed thicker paper through a folder the thicker paper can rub against the steel rails of a buckle style fold pate, scuffing from the rollers or delivery guides can also be a problem. This can leave streaks through your work, especially when you have full dark colour coverage on the job and result in wastage and expensive overruns.
Machinery like the Morgana DigiFold Pro, and the similar one Morgana Digifold 385, and Morgana AutoFold Pro have been specifically designed to crease and fold heavy substrates up to 400 GSM. They use Morgana’s patented “flying knife” technology (see figure 1). This allows delicate digital stocks, cross-grained paper, and heavyweight stocks to be folded without any of the scratching and marking caused with conventional folders. Users will benefit from the simplicity of the system which will give unparalleled performance and longevity and an easy set up through a simple touch screen. To simplify the explanation of how knife folders work, there is a blunt knife that pushes the paper stock in between large fold rollers (see figure 2).
With the knife folding mechanism eliminating marking and curling of the stocks, these machines also work inline with technology like Morgana's DynaCrease system to eliminate the cracking of toner and paper stock. This technology gives users the ability to run at speeds to over 6,000 8.5" x 11" sheets per hour. Speed increases when running smaller stocks and is achieved by creasing the sheet without stopping it, yet maintaining an accuracy of +/- 0.003".
Click HERE for a video demonstration
Limitations of knife folders:
The one limitation that knife folders do have however is to maintain their high level of accuracy they rely on the paper stock being processed to have some weight to it. Although stated in some of the specifications of the machines available, attempting to use a knife folder to reliably and accurately fold stocks under 80lbs becomes a bit of a challenge. As the sheets travel through the folding process the lighter stock has less body to it, so it tends to have a lot more flex which leads to folds in the wrong position or ultimately jamming of the stock in the machine.
When making your final decision on what folder below are some of the factors that will come into play. Please be sure to contact your Sydney Stone representative who can help guide you through your purchase.
- What are my minimum and maximum sheet size requirements?
- Your minimum and maximum paperweights you plan to fold?
- What kind of volume do you plan on running?
- How are your stocks being printed – digitally or on offset?
- Have you picked a good partner for long term support?
Shops need to look at the big picture of what they plan on running and if they need to run the full range of stocks having both technologies will ensure each machine is running what they were ultimately designed to do.