To rout or knife-cut?
So, Duff Graphics purchased a router with a 4-hp spindle and tangential knife configuration, designed with standard features for sign manufacturing. The combination of routing and knife cutting vastly enhances the company’s capabilities, with the versatility needed to cut many types of sign substrates.
The routing spindle is well-suited for cutting through high-density materials, for example, while the knife cartridge is better at cutting intricate shapes with thinner, low-density materials, as it has a fine, pointed edge.
The machine’s drag knife can be used to cut many different types of low-density materials, including cardboard and vinyl, but encounters limitations with foam core, which needs to be ‘sliced.’ An oscillating knife alleviates this constraint, as its pulsating action works better at tearing the foam, providing high-quality edges. Another option for cutting ‘peel and stick’ vinyl is the spring-loaded kiss-cut knife, which can adjust for the depth of the cut. It essentially ‘imprints’ a cut to define individual decals and allow them to be easily removed from their non-adhesive back liner.
“As of right now, the spindle for routing is the most-used feature, cutting dense plastics, followed by the drag knife for vinyl and then the oscillating knife for foam core,” says Bob Vartanian, Duff Graphics’ machine operator, who has worked for the company for more than 25 years. “These diverse capabilities have translated into huge improvements in job turnaround time, as the production process has been streamlined.”
In addition to the immense time savings, Vartanian cites the increased range of jobs the machine is allowing the company to take on.
Before the installation, Duff Graphics mainly handled jobs that involved straight-line cutting by hand, using a 27-kg (60-lb) ruler and an exacto knife. After the printed graphics were cut this way, a drill press was used to punch holes through the signs for hanging purposes.
As Vartanian puts it, the new machine has saved his body, as cutting everything by hand was very physically straining for him. Now, instead of hand-cutting and using the drill to punch holes, these processes are consolidated in the machine, which can both cut and punch on the table in a matter of minutes.
By way of comparison, hand-cutting an approximately 1-m (3.3-ft) long straight edge through 3-mm (0.12-in.) thick styrene with a ruler used to take three to four minutes to complete. Now, the machine can cut that same straight edge in a few seconds.
“The router can take away a lot of extra processes and body strain,” says Vartanian, “and it provides an end result you would not believe. Its accuracy is amazing when it comes to contour cutting.”
One of the key requirements for these capabilities is a digital camera and optical registration system, for both routing and knife cutting. The camera detects registration marks (or ‘fiducials’) that have been added to the print file to aid the cutting process. Upon mark detection, the registration system uses the collected information to accurately locate the images to be cut, adjusting the machine for image distortion, drift and rotation.
This way, even if an image is not placed precisely on the table, the system will register the marks to ensure the correct cutting, whether this involves a straight line or complex contours. For Duff Graphics, this technology means every job can now be completed perfectly.
“If you’re a perfectionist, then the vision system should be equipped on your machine,” says Vartanian. “The camera delivers the accuracy needed for contour cutting. It’s the best asset on the machine.”