High-speed. Accurate. Versatile. You want your die cutting method to fulfill your needs because it’s an essential part of manufacturing. Realistically, however, you may have to make some choices based on the project’s priorities. High precision or high volume? Super speed or complex cuts? Low cost or low maintenance?
Before exploring the three most popular types of die cutting — flat bed, rotary, and laser — let’s review what die cutting is and why it’s so beneficial.
Basically, a die is a tool, usually made of metal, that cuts material (paper, plastic, fabric, adhesive, and many more) to create pieces that are identical in size and shape. Used to benefit many industries, die cutting offers different advantages, depending on the type of project.
So, what is the difference between rotary die cut and flat bed? How is laser cut different from both of them? Now is the perfect point to provide a brief overview of different methods.
• Flatbed die cutting: As its name implies, a hydraulic flatbed press pushes down blades that cut material to the desired shape.
• Rotary die cutting: A cylindrical die, with blades around the entire cylinder, cuts shapes out of the material, moving in a circular motion. This efficient movement cuts out numerous identical shapes as it rotates.
• Laser die cutting: Instead of using steel blades to create the desired shape, a laser’s light sears the material. This easily cuts complex shapes into many materials, yet this process destroys other materials and some adhesives.
Pros and Cons of Each Die Cutting Method
Now that you understand each method’s basic mechanics, let’s dive into how each excels and how each has limitations. Keep this in mind: just like any manufacturing process, the most efficient method is usually the one that best matches the project’s needs.
Flatbed die cutting: simple can be very useful
Although this is the most basic method of die cutting a material, flatbed die cutting can be the method of choice for certain projects. A cutting die is fabricated and placed in a hydraulic press, which allows it to cleanly cut thick material and material in a sheeted form. Flat bed die cutting stamps out simple shapes, similar to a cookie-cutter.
Tools can be changed out easily and quickly, making flat bed die cutting the right choice for low-volume projects, or if a product isn’t working properly on a rotary or laser cutting machine.
Rotary die cutting: best for high-volume projects
Think of this method as taking flat bed’s cookie-cutter approach and adding a rolling pin. A rotary die cutting cylinder allows for multiple and continuous shapes to be cut very quickly from material provided in roll form.
The press’s rotating cylinder blade cuts the material to exact lengths, keeping tight tolerances by using servo motors to maintain registration. Rotary dies, known for their durability, can cut rolls of material that perfectly fit on same-sized objects, a critical advantage for parts in the medical, military, and aerospace industries, among others.
Laser die cutting: no blades needed
Not requiring any contact with the material, laser die cutting uses a high-speed laser to perform a variety of cuts. It’s a highly repeatable process that allows for extremely small details to be accurately cut.
Laser die cutting is often selected for the precision cutting of flexible materials (tapes, rubber, laminates), adhesives, and materials that would otherwise damage traditional die cutting steel. One example is converting sanding discs into round shapes that fit a flat sander. Those are cut with lasers because the sandpaper itself would quickly wear down a rotary or flat bed die cutting blade.
Checking the Boxes: Which Die Cutting Method Wins?
[ ] Speed
Laser cutting is precise but not fast; it needs to adjust and follow its cutting shape. A rotary die already has the shape set and can quickly repeat that cut over and over.
Advantage: Rotary die cutting
[ ] High Precision
Laser die cutting is fantastic for intricate, complex shapes with tight precision and finishing; both rotary and flatbed are limited by how close blades can be placed together.
Advantage: Laser die cutting
[ ] High Volume
Cutting the same shape across many pieces of material isn’t always easy, especially if the material is thick. When converting bulk orders quickly, lasers fall short.
Advantage: Rotary die cutting
[ ] Cleanest Possible Cut
The reason laser die cutting doesn’t win here is because of laser ablation. The high-intensity laser beam melts or burns a material to get through it, leaving some residue behind, on the edge of the cut.
Advantage: Rotary die cutting and flat bed die cutting
[ ] Prototype Friendly
When a quick prototype is needed, it’s easier and cheaper to use laser die cutting than to acquire and perform hard tooling. If high volume is eventually required, an investment in rotary die cutting can be made.
Advantage: Laser die cutting
[ ] Clean Air While Cutting
As mentioned, lasers burn/melt materials, which can give off fumes and smoke ranging from inconvenient to harmful, depending on the material. For instance, when PVC is cut with a laser, the byproduct is chlorine gas. Also, smoke can negatively affect the laser’s cutting performance, possibly producing an inconsistent cut.
Advantage: Rotary die cutting and flat bed die cutting
[ ] Deep Cuts or Multi-Layer Cuts
In general, laser die cutting isn’t effective on thick material and many layers. Lasers are set for one cut depth, while flatbed and rotary allow cutting through two layers, for instance, and not a third layer.
Advantage: Rotary die cutting and flat bed die cutting
[ ] User-Friendly
Training on a laser die cutter is simple, and operation is easy. Both flat bed and rotary die cutters have more working parts. For instance, the die within a rotary die cutter needs to be physically replaced after it wears down, which requires operator training.
Advantage: Laser die cutting
[ ] Material Variation
Laser die cutting is limited by the material being converted more so than other methods. It also depends on what type of laser is doing the cutting. Wavelengths differ, so some materials — conductive material, high-temperature plastics, polycarbonate, etc. — can’t be effectively cut by many lasers.
Advantage: Rotary die cutting and flat bed die cutting
[ ] Minimize Maintenance
Rotary and flat bed cutters are like other mechanical equipment, requiring refurbishing or replacing when the metal-cutting dies get blunt. Continuous maintenance and potential downtime aren't issues with laser die-cutting.
Advantage: Laser die cutting
Unique Challenges of Laser Die Cutting
When converting using rotary and flatbed die cutting methods, the material itself remains unchanged; it’s simply cut, removing what is not needed. As we’ve addressed, laser die cutting alters the physical condition of the material, which needs to be considered.
Are the edges of the part being cut critical to its performance? Because, after converting, if a laser burns an edge enough to alter its performance, it may not be the best die cutting method for that part.
Wavelength is also a challenge of laser die cutting, making sure that the material can be cut with the wavelength of that particular laser. If the material doesn't receive the laser well, the cut won’t happen; if the material takes the laser too much, the material will burn.
Mini-Case Study: Laser Light
In addition to a laser’s ability to char a material, its light may also be a factor. Here’s an example. A reagent — a substance that tests if a reaction occurs — was impregnated into a multi-layered paper for a medical test device. The reagent couldn’t function correctly if the wavelength of light was above a certain luminous flux (the measure of the perceived power of light). Strouse’s laser — set up in a controlled, cleanroom environment — cut the part and maintained product integrity because the laser’s light was controlled and concentrated to a small area.
Converting a material usually involves an adhesive. Normally during die cutting, the edge of what’s being cut has the adhesive — typically a pressure sensitive adhesive — exposed, so it’s sticky. Sometimes, that’s fine, and other times it prevents the part from doing what it needs to do. When die cutting with a laser, the charred edge (changing the chemistry of the polymers) reduces stickiness and retains performance. However, when 3M™ VHB™ tape is laser cut, for instance, it melts into a liquid state that isn’t desirable.
Determining the quality of a die cut is the same for flat bed, rotary, and laser die cutting methods. The only challenge with laser cutting is deciding how that measurement will happen. While the blade used in rotary and flat bed die cutting makes a clean edge, a laser actually is irregular, with tiny hills and valleys. So, it must be determined how to measure a laser’s cut: is it a line across all the “hills,” or the “valleys,” or is it split down the middle?
Most converters count on their die cutting as their bread and butter service. Yet, not all invest in the latest equipment and in-house talent to offer flat bed, rotary, and laser die cutting expertise like Strouse. As an experienced, industry-leading converter, Strouse’s team of engineers designs press diagrams and gets jobs running, while the quality team performs set-up and final inspection of parts, ensuring tolerances are met.
Speaking of expert converting, you’re invited to learn more by reading our Flexible Material Converting Q&A Guide. It features common questions asked of adhesive converters and their answers. Need help now? Call Stouse today (800)-410-8273, or ask an engineer!
