By Lisa Guerriero
Print service providers (PSPs) regularly work with many rigid substrates. The variety enhances the need for advanced finishing capabilities. Different tools can be used to cut or rout foamboard, paper- and fiber-based material, plastic, aluminum and aluminum composite material (ACM), and alternative materials like wood, rubber, and glass. Many are used interchangeably on one cutting and routing system.
Speed, typically measured in revolutions per minute (rpm) and engine power, measured in horsepower (hp), are key components when it comes to choosing the correct tool. Higher power bits, blades, or knives enable the finishing of thicker, heavier substrates. In addition to speed and engine power, substrate thickness, rigidity, and material type determine tool selection.
Drag or oscillating knives are effective for foamboard, providing a smoothly cut surface. Based on Esko’s Bits and Blades Catalog, published in 2015, oscillating blades used for foamboard are ideal at frequency ranges from 4,000 to 12,000 strokes per minute.
Drag knives are easy to use and substantially faster than oscillating. They are ideal for simple shapes like rectangles and circles. They are not as well suited to complex cuts with sharp angles or tight radii.
“The more intricate a shape with sharp angles, the more likely the oscillating tool is a better fit,” explains Lara Waden, sales administrator, Colex Industries.
Higher force cutting tools, like oscillating blades, are ideal for thicker foamboard. Drag knives are typically effective for media under a quarter inch, whereas oscillating blades accommodate media four times thicker, suggests Waden.
Beatrice Drury, director of marketing and communications, Zünd America, agrees that oscillating tools are better for thick material and detailed contours. However, she adds that “denser, plastic-based foamboard is generally routed.”
Routing is often required to cut into foam products that are especially rigid. For softer foams with more give, routing may be too harsh.
“An oscillating knife blade will provide a smooth cut into the foam whereas a router bit will leave a poor surface finish,” says Roy Valentine, sales, Techno CNC Systems.
Companies like Vision Engraving & Routing Systems continue to introduce oscillating knives to the mix to enable routing through semi-rigid materials such as foamboard, which help enhance substrate versatility.
Paper- and Fiber-Based
Flexible paper media is one of the easiest substrates to cut. For products on the more rigid end of spectrum, the tool must be matched to the specific type of paper- or fiber-based material.
“Some of the high-fiber boards are more challenging and tooling varies depending upon the abrasiveness of the material. They could require more hardened or carbon-type tools to hold up under the strength of the materials,” suggests Larry Moore, VP – partner programs, North America, Esko.
Drag knives handle some of the thinner semi-rigid paper products. More rigid media, as well as thicker products, usually require a power tool—a vibrating or oscillating blade. Laser cutting is also an option for some products, like fiberboard.
“An electronic oscillating tool uses an electronically controlled blade that oscillates to cut through cardboard, corrugated boards, and paper foamboards,” notes Shado Norstegaard, lead designer, Summa, Inc.
Crease wheels are commonly used for folding carton and paper-based substrates. The width of the wheel—commonly in millimeters (mm)—determines its media compatibility. For example, a crease wheel of 60 mm is ideal for thicker paper material like corrugated board. It can crease deeper into the board without cracking the liner, according to Esko.
Mimaki USA, Inc. recommends using a cutter’s tangential tool for fluted cardboard and coated cardboard up to two mm. A reciprocating tool is better for regular cardboard up to ten mm thick, as well as non-paper substrates like foamboard and sponge.
The reciprocating blade “cuts thick materials by vibrating a blade up and down,” explains Ken VanHorn, director, marketing and business development, Mimaki.
Plastic is a diverse substrate category with numerous options, so cutting tools vary widely. Drag knives are appropriate for flexible plastics, as well as thinner semi-rigid media.
“For example, a dual-wedge blade can be used for added durability and performance when kiss-cutting polypropylene sheets and thin polycarbonate,” suggests Summa’s Norstegaard.
Although not as common, some drag tools can also cut rigid plastic like Sintra, as long as it’s a thinner board—typically a quarter inch.
More often, highly rigid plastics and thicker plastics require advanced tooling—either oscillation blades or a router. These methods are suitable for materials like polycarbonate and PVC.
Router bits allow the print provider to tailor the cut for different kinds of plastics. With acrylic, the challenge is leaving a polished edge so that no further finishing processes are necessary.
“For acrylic, the router is your only choice and for getting the cleanest edge quality possible, make sure the bit size cutting length is close to the thickness of the media in measurement,” suggests Waden.
Milling bits used on Esko devices are run at a recommended rpm between 30,000 and 60,000 for acrylic and PVC. The precise number is determined based on the sharpness of the bit tip, diameter of the tip, and spiral length of the bit.
MultiCam Inc. recommends routing instead of knives for polycarbonate, polypropylene, polyurethane, and PVC. For some polymers, like polypropylene, it also suggests laser cutting.
Steve Aranoff, VP sales and marketing, MCT, agrees laser-based tools offer a viable alternative.
“For non-PVC plastics, a laser may do an even better job, as it provides flame-polished edges without a second process,” he adds.
Aluminum and ACM
Aluminum and ACM have similar cutting needs. Compared to media optimized for digital print, products made from these substrates tend to be heavy and rigid.
Routers are a go-to method. An advanced or heavy-duty model is preferred. Entry-level or light-duty models may be effective, but only with thinner aluminum or ACM products, and vendors recommend testing the material.
Routers come with multiple bits and spindles to facilitate varied media handling, including sizes and types geared toward metal substrates.
“High-power spindles are essential for processing tougher materials such as wood, aluminum, and hard plastics,” says Robert Marshall, VP market development, AXYZ International. To accommodate heavier substrates, AXYZ’s routing spindles range in power up to ten hp.
ACM products aren’t as heavy as straight aluminum, but a heavy-duty router “is still the best choice for the various thicknesses print providers may encounter,” suggests Dana Goodale, director of product management, Gerber Scientific, Inc. The Gerber Sabre 408 features a seven hp spindle built for heavy substrates.
Routing systems are frequently offered with an optional misting system. It applies a layer of lubricant to the cutting tool, ensuring a good finish when processing aluminum and promoting tool longevity.
As PSPs expand into new applications and substrates—including wood, rubber, and glass—challenges are present.
Though printing wood generally involves products classified as lightweight, the media is still heavier and more solid than traditional digital substrates. For this reason, routers are ideal.
Roberto Rodriguez, president, Digital Graphic Systems Inc. (DGS), recommends using a spindle router for wood as well as medium density fiberboard (MDF), an engineered wood with a smooth finish. DGS’ DYSS V-PRO X5 now offers a high-frequency spindle at 60,000 rpm to cut hard materials like MDF.
Not all wood is the same, and that means routing tools must also vary, points out Valentine. “There is an assortment of tools used for various woods. For composite woods, compression bits are typically used; for solid woods, a spiral up cut can be used,” he continues.
Laser systems also cut wood, notes Aranoff.
The tangential tool on Mimaki’s CF2 Series and new CFL-605RT cutters enables a variety of media up to two mm, including synthetic leather and rubber.
“Using the motor, it cuts material while allowing the line to automatically control the edge of the blade,” says VanHorn.
Glass can’t be cut by most digital finishing systems. It requires a specialized cutting solution, such as the MultiCam WaterJet systems, which cut tempered and regular glass in addition to many other rigid and flexible substrates.
In addition to providing tools for various substrates, other aspects of a finishing solution can benefit a print provider. The design and features of the system help ensure quality and productivity.
A vacuum-based system is key. “Media is held down securely on the flatbed with a vacuum system; it is possible to cut with higher cutting pressure than a roll feed cutter,” says Juan Carlos Cabrera, application engineer, Graphtec America, Inc.
Some cutters allow the print provider to optimize suction for cutting different media types and sizes.
David Paine, national sales manager, Omnitech Systems Inc., says the carbide tools on a CNC router can cut any substrate a print provider uses. The success of the cut isn’t just about the substrate, he says. Other factors include system conditions like hold-down capacity, rotational speed, and cutting feed rates.
Table needs are different for laser solutions, points out Aranoff. An aluminum surface or conveyor capability is required—or in MCT’s case, roll automation that enables laser and knife cutting.
Flatbed systems also require accurate leveling, which must be maintained over time. Some have an automatic mapping feature that detects small differences in table height and adjusts the height of the tool depth.
“Even slight variations can have a serious impact on expensive materials that are being finished to very fine measurements,” explains Esko’s Moore.
Solutions typically hold at least two tooling implements simultaneously. PSPs load up the most frequently used tools, enabling fast and easy changeover. Systems that offer automated tool changeover are particularly competitive for digital print providers, especially those using numerous types of substrates on a regular basis.
“Switching from one type of tool to another—from kiss cutting to through cutting, or cutting to creasing, or even routing to polishing—happens automatically by virtue of the tool assignments embedded in the cut file,” explains Drury.
Changing out router bits takes a few minutes if done manually, but software-driven systems facilitate the process. “Switching is as simple as specifying a different tool in the job,” suggests Goodale.
A Smoother Cut
No one blade can effectively cut all the substrates available to digital print providers, particularly the many rigid materials. Digital cutter and router solutions offer versatility, whether the job involves foamboard, paper- or fiber-based media, plastic, aluminum or ACM, or alternative material like wood, rubber, or glass.
These systems enable print providers to match the tool to the material based on the thickness and consistency of the media as well as the substrate type. The finishing solution’s engine components and layout further improve productivity. They make it possible to secure media and shift quickly between tools, even for jobs that require challenging materials and multiple substrates.
Sep2015, Digital Output