Slicing into New Opportunities With Digital Cutting Technology
Discover how digital cutting systems work and how various models differ.
In the race to stay one step ahead of the competition, many screen printers find themselves searching for unique products to add to their mix or ways to improve their turnaround time and service in order to gain an edge in an increasingly competitive marketplace. One way for screen shops to both broaden their product offerings and secure new clients is to add digital cutting equipment to their operations.
You can use computer-driven cutting machines to produce shaped P-O-P graphics, signage, decals, and other indoor and outdoor products that you might not have considered offering before. And as you'll learn in pages that follow, the benefits of adding this equipment to your operation aren't limited to the production department.
Types of cutting systems
Cutting plotters, frequently referred to as vinyl cutters or computer-aided-signage (CAS) systems, can be used for a variety of applications in a range of markets. Cutting labels and decals, trimming posters and banners, producing packaging prototypes, and contour cutting and routing rigid graphic displays are examples of jobs suited to digital cutters. Before we get into the opportunities your shop can pursue with the addition of digital cutting equipment, let's take a close look at the types of cutting systems available and the technology behind them.
Although cutting plotters come in a variety of sizes and styles, all machines fall into one of two general categories: flatbed or roll-fed. Flatbed cutters are large-format systems that use a vacuum bed to hold materials in place during cutting (Figure 1). The cutting head on a flatbed system moves in X and Y directions across the surface of the media. Flatbed cutters can be used with vinyl film and other flexible media, but they are used mainly for thick, rigid, sheet-fed materials. These devices are ideal for applications that require a high amount of cutting force.
Roll-fed (or drum-fed) cutters are used with flexible roll materials that are pulled or fed through the machine (Figure 2). These systems use either friction- or sprocket-feed technology to transport substrates. Materials on friction-feed cutters move backward and forward via grit rollers, which are located underneath the media and serve as the driving mechanism. Pinch rollers located above the material lower onto the substrate and hold it in place. The cutting head moves back and forth across the media on an axis that is perpendicular to the feed direction of the material. On sprocket-fed systems, sprocket-like wheels grip and pull the material via prepunched holes in the material's edge. Roll-fed systems are suitable for cutting PVC stock, reflective films, and other substrates used for decals and signage applications.
Cost and speed are two main draws to friction-based, roll-fed cutters. Today, a sign shop can purchase a 50-in. friction cutter for approximately $5000 and expect speeds as high as 44 in./sec. Friction-based cutters also accept a wide range of media, punched or unpunched, in a variety of widths. Because the friction cutter accepts punched material, many shops find that they are able to use up scrap material from previous jobs, thereby eliminating waste mate-rial and the costs associated with it.
Friction-fed cutters offer many advantages, but there are considerations to keep in mind. Sean Childs, product manager at Gerber Scientific Products, says a friction cutter's accuracy is good, but does not measure up to the accuracy offered by sprocket-fed cutters. Additionally, because friction-fed cutters rely on user skill for manually loading material, jobs can be ruined easily when user skill is not up to par. Friction-fed cutters also do not allow for unattended operation.
Childs explains that sprocket-fed systems, while slower (top linear speed is 36 in./sec), offer better image alignment than friction-fed systems because the sprockets lock the material in place, preventing it from shifting position. He points out that the high degree of accuracy is especially important in jobs that involve layering.
"If you're producing a three-color sign, you grab three different colors of vinyl, cut them out, and then layer them," Childs says. "If you do a shadow, a block letter, and some highlights on top, you want to make sure that everything lines up. You don't want to be repositioning pieces of vinyl during application."
Sprocket-fed systems also allow for unattended operation—a big plus in any graphics shop. This means that users can load a 50-yd roll of vinyl, hit the start button, close up shop, go home for the night, and return to the shop the next morning to find a completed job that meets expectations.
Childs notes that material loading also is quick and easy with sprocket-fed cutters. These machines are compatible with various types of vinyl. However, because the sprockets are fixed, you can only use materials of the width for which the cutter was designed the materials must be punched. On friction-feed cutters, you can use material of any width, up to the maximum that the device will support.
The cutting edge
The two main types of knives or blades used in vinyl cutters are swivel and tangential. A swivel knife, also called a drag knife, follows the designated cutting path without raising up from the substrate. A tangential knife, on the other hand, is a fixed-position blade that constantly lifts and turns in the direction of the cut. Tangential knives are typically suited to cutting thick materials and intricate designs.
Many cutters allow users to switch between swivel and tangential cutting with the push of a button. Users may also be able to control blade-related functions, such as cutting force (weight) and speed, through an LCD interface. On some systems, a dial gives users control over the weight of the blade.
Flatbed cutting systems may be equipped with laser heads that perform the cutting function. These machines also can be fitted with tools that accommodate various cutting and creasing requirements, as well as routing and engraving functions (Figure 3). Some may also allow operators to alternate between a knife and plotting pen.
When it comes to swivel cutters, 45° or 60° blades are the norm. Rick Rivera, applications engineer at Roland, explains that the 45° blades are used for general applications, such as vinyl, heat-transfer materials, and thin stock, while the 60° blades are used for detailed cuts, tiny letters, and thick materials that require the blade to punch through.
Among the types of blades available, the two most commonly used in digital cutting systems are supersteel and sapphire. According to Neal Baessler of Graphtec America, supersteel blades are suitable for general cutting applications. He says sapphire blades are especially suited for cutting Rubylith for screenmaking. "It cuts through the film without having to score the backing, which often causes refractions when you are exposing a screen," he says.
Many flatbed cutting systems are equipped with tool inserts to support a variety of cutting functions. Kiss-cutting blades are available for pressure-sensitive vinyl films to cut the film with cutting the backing liner. Oscillating knives are used for corrugated materials, foam, and folding carton. Tools for creasing, engraving, routing, and pen plotting also are available. Pen-plotting tools, originally designed for AutoCAD applications, can provide screen printers with a way to demonstrate to a client what a finished sign will look like when it's cut.
Some cutting systems use servo-motors to drive blades and material-feeding mechanisms. The servomotor is a closed-loop system in which the motor's controls constantly monitor the motion and distance of the carriage head. On some systems, namely sprocket-fed cutters, you'll find stepper motors, which are less expensive than servo motors and are not equipped to monitor the carriage head's movement. Rivera notes that servomotor-driven cutters have improved speed and cut quality over the years, especially in applications that involve complex curves and arcs. He says stepper motors can leave jagged edges on complex curves.
Cutting force and speed
Cutting plotters, depending on the brand and model, support media in widths ranging from 15-55 in. and cutting widths between 13-52 in. Several large-format systems also are available that offer cutting widths from 72-126 in. Desktop cutters are another option and support cutting widths between 6-14 in. (Figure 4). Most systems offer cutting forces up to 600 g. Some large-format flatbed systems can deliver a maximum cutting force up to 5000 g.
Cutting speeds on flatbed systems are as high as 55 in/sec, while roll-fed systems typically deliver speeds between 30-40 in./sec (some systems, however, can reach speeds as high as 60 in./sec). Speeds on desktop systems usually top off at 6 in./ sec, though a few models can cut faster than 20 in./sec.
Some manufacturers differentiate between axial and diagonal cutting speeds. Most measure cutting speed in diagonal terms (where all axes are measured), but others measure speed along a single axis. In general, cutting accuracy on most digital systems falls at ±0.001 in. Mechanical resolution ranges between ±0.0001-0.0002 in. Resolution may be defined as mechanical or programmable. The former refers to the resolution that the cutting device can achieve mechanically. The latter refers to the resolution that can be addressed by entering in a desired number.
Bells and whistles
Cutting systems may be equipped with a registration and alignment systems that use laser beams or CCD cameras to optically locate and analyze registration marks and other targets that are printed along with graphics to align the cutting path (Figure 5). These systems are designed to automatically compensate for any distortions, material changes, and dimensional changes in the material. Some cutters even come with a remote alert system that sends a text message to the operator's mobile phone during unsupervised operation.
Plenty of optional accessories are available to extend the cutter's functionality and improve efficiency. Conveyors and sheet-feeding systems, media baskets, blade and pen holders, and pouncing tools are examples. Pouncing tools can be used to apply a design to substrates with irregular surfaces. Instead of placing vinyl or another material onto the cutting device, users place a piece of paper onto the cutter, and with the pouncing tool, pounce out holes for a graphic design. Users then place the piece of paper against the irregular substrate and rub special chalk or charcoal over the holes in the paper, which leaves an outline of the graphic design on the surface, over which users can paint the final design.
Some manufacturers offer cutting systems that perform both printing and cutting functions (Figure 6). These machines combine inkjet printing and high-speed cutting for applications such as banners, vehicle graphics, signage, and more.
Many companies offer graphic- and sign-design software programs for use with cutting devices, as well as routers and engravers. The software, which usually is designed for creating images for output on inkjet or thermal-transfer printers, also can be used to send information to the vinyl-cutting device. Several manu-facturers bundle software programs with their cutting devices.
Users of software for vinyl cutting find many of the same features and functions offered in popular graphic-design programs, such as Adobe Photoshop, Adobe Illustrator, and CorelDRAW. Tools for design and editing, creating special effects, cutting, and output are usually standard. Graphic-design and editing tools may support file import, dragging and dropping images, various font formats, special shapes and borders, text setting and alignment, layering, dimensioning, creation of vector-based shapes, tiling of large images, color trapping, adjusting color gradients, and more.
The software often includes tools for creating special effects, including 3-D effects, shadows, rounded corners, outlines, distortions, chisel effects, and many others. Cutting functions supported might include user-defined vertical and horizontal weeding lines, cut by color, contour cutting with automatic bleed, and multiple cutting passes for thick materials. Users also may be able to reverse, swap axis, repeat, and size jobs without affecting the saved file.
How much will it cost me?
A shop today can purchase a 24-in. roll-fed friction cutter for $2000-$3000. A 50-in. roll-fed cutter requires an investment in the ballpark of $5000-$7000. That same shop can also, depending on its needs, purchase an industrial-sized flatbed cutter in the price range of $35,000-$150,000. Pricing for the industrial-sized units typically depends on the type of tooling included with the cutting system. Pricing on all cutting machines also may be determined by the software offered with the system, as well as the warranty.
Childs says cutter technology definitely has improved over the past decade. "Manufacturers realized that they had to have a good price tag, and also a good product," he notes. "Technology improved, manufacturing methods improved, and these systems got so much better.... There was, at one time, a race for speed, but the users realized that just because you can buy a car that goes 200 mph doesn't mean you'll ever actually go 200 mph. You just want [the cutter] to be reliable, consistent, and user friendly."
Cutting plotters can open the door to new business and new profits for any type of screen-printing company. Graphic shops can use them to add a finishing touch to retail displays. Garment printers can use them to custom cut transfers and appliqué, as well as to expand into products such as signage and decals. And industrial printers can benefit from the technology when producing short-runs and prototypes for graphic overlays, product-identification labels, and more. For any shop that wants to remain a cut above the competition, digital plotting technology is worth considering.