Die-cutting developments continue unabated.
- Published: October 01, 1995
Fierce competition among cutting die manufacturers is resulting in a better, less expensive product for all converters, and it's not going to stop here.
What do you want your cutting dies to do? That's the key question, because today's dies have evolved to a point where they can be designed to do whatever you want them to.
Everything depends on the application. Customers don't care what kind of technology is used as long as the product meets their specs. If, for example, you were asked to make a one-of-a-kind folding carton, it could be constructed with a razor blade and scissors. If the customer commissions ten cartons, you might build a fixture or a jig. An order for 1,000 or more would call for a steel rule die and a press. And if the order is for many thousands or millions, you may decide that the extra expense of a rotary die machined out of tungsten carbide is justified.
"Each and every one of our die-cutters is custom-made," says Barry O'Connor, VP of engineering for CORfine Inc., Muncie, IN, a manufacturer of die-cutting machinery. "If you want high speed, we can build machines that run at 800 feet per minute. On the other hand, an extruder will need something much slower, and we can build a machine that operates as slowly as three feet per minute. It all depends on the customer's specific needs and applications."
There are several different die-cutting technologies available. Each one has its own niche, and each one has been perfected to the point where it does its specific job very well.
The woodbacked steel rule die has been with us for a long time, for good reason. There are certain applications, such as cutting corrugated materials and thick paper-boards, in which its taller, more pronounced, deeper-cutting knife edge is the best, most economical choice. When you consider a steel rule's much lower initial cost - about one tenth the cost of a machined steel rotary die - and the fact that it can be reknifed several times, it's not difficult to see why this old standby remains a cost-effective and efficient industry workhorse. In fact, the "old standby" woodbacked steel rule die continues to be improved through research and development. One example: It is common today to find computer-guided laser cutting of the slot in the plywood cylinder into which the steel rule is inserted.
The slot cutting accuracy of a skilled jigsaw artisan, says Bob Lackey, VP of marketing for Southeastern Die Co., Decatur, GA, may occasionally reach [+ or -] 0.015; the accuracy of a laser-cut die is consistently within [+ or -] 0.005. This greater accuracy allows machinery manufacturers to build faster folding, gluing and packaging machines.
The tighter tolerances realized by laser cutting have been a great advance, but they've also created a problem. The repeated removal and replacement of dull rules eventually wears out the slot. Rules are held in place by the friction between the kerf and cutting knife. So, as the slot wears, the kerf gets wider, eventually becoming so sloppy that the die can no longer be reknifed, necessitating the creation of a new cutting die.
To solve this problem Southeastern Die Co. has developed a patented knife-holding system that uses spring-loaded ball bearings pressing against the base of the rule to not only hold it in place but to allow the steel rule to fully level after a few machine impressions. This die, called the NeverDie, can be reruled an unlimited number of times, and the ISO-9002-certified company guarantees the rule will not fall out during production runs.
Another computer-inspired leap in woodbacked die development is the relatively new CNC rule-bending machine. Computer accuracy, repeatability and speed have automated another aspect of die-cutting that just a short time ago required skill and manual labor.
Genline Systems, Conyers, GA, offers Windows-based software for the diemaker. Interactive packaging design software, or IPDS, provides diemakers with features such as automatic bridging, rotary bridging and digitizing complex shapes. To operate, you create the desired cutting die shape with the software's CAD/CAM feature as if it were flat, and then the software wraps the design around an on-screen 3-D cylinder and automatically compensates for any stretching or distortion. The software also is designed to interface with the previously mentioned CNC rule-bending machines, offering diemakers all the advantages of computer-assisted design.
CNC, or fully machined rotary dies, have the highest speed and accuracy potential in terms of cost/thousand. These systems continue to be pushed forward by developments in materials, hardening through innovations in heat treating, and new kinds of anvils, as well as replaceable blankets and cutting sleeves.
On another front, the flexible die-cutter is beginning to gain adherents with each passing year. Flexible dies are not new; American Can Co. pioneered the use of thin, chemically etched cutting plates in the mid 1960s. What is new is their rapid development.
According to Edward Porento Sr., president of Best Cutting Die, Skokie, IL, the early versions of flexible die-cutting were not nearly as good as they are today. "They have come a long way in a short time," says the veteran of more than 40 years of diemaking.
Advances include improvements in mounting the flexible die onto the cylinder, either mechanical or magnetic, as well as improvements in the manufacture of the cutting die. The cylinder itself is a work of art, featuring many individually controllable vacuum ports that offer 360 [degrees] control of the blank and chips. After a cut cycle is completed, a jet of air is directed through the cylinder to blow out the offal before the next cut is started. Porento reports that these dies, which can operate at high speeds, have been perfected and "are coming on strong."
One of the advantages of flexible dies is their quick changeover capability. Everyone is looking to minimize downtime, and, with flexible dies, only the thin die is removed - the cylinder remains in the machine.
As long as there is competition, manufacturers will continue to search for ways to enhance productivity and speed up the production process. Allan Pfaff, the chairman of Atlantic Eagle, Farmington Hills, MI, says, "It takes much too long to get a rotary die to the customer. My goal is to cut the lead time from 20 weeks to 15 working days." He plans on reaching this goal by using the latest computers and software, computer transfer of engineering data and the latest CNC die manufacturing technology.
Although cutting dies have been with us for more than a century, their evolution continues. On the horizon are exciting new developments such as the UltraMicroperf perforating die from Zimmer Industries Inc., Hawthorne, NJ, and advances in ultrasonic die-cutting, suggesting that the future pace of development will be even faster.
By American Die Technology, Suwanee, GA
The Thermalizer is designed for die-cutting thermal film and paper. Its durability is enhanced by the company's patented metal finishing process. The Marathon is a die that's fully hardened by the mfr.'s specialized heat-treating process. It's said to offer excellent wear resistance for long runs and steel-to-steel applications. Both are manufactured with high quality steel and are fully hardened for extreme durability. They are recommended for intricate shapes, tight spacing and small cavities.
