Flexible die technology has advanced tremendously over the past 25 years. Today, converters continue the advancement of replacing solid tooling with flexible dies for many reasons, including:
- The ability to hold tight tolerances as low as +/- 1-μm.
- Versatility of many substrates that can be converted
- Ease of storage and light weight
- Fast manufacturing turnaround times
- The life of a die—millions of revolutions can be achieved on certain substrates and conditions
- Multi-level heights
- ROI of converting from solid tooling to flexible tooling can be a huge cost savings over a short period of time
Critical Flexible Die Factors
When ordering a flexible die, there are several critical factors every manufacturer will need to know, such as:
Material: The material specification is important in order to determine the die height and cutting angle. The face material is used to determine the cutting angle and the liner determines the die height. If an overlaminate is being applied, it is also important to inform your die supplier of this, so any relevant changes to the blade angle can be made accordingly.
In addition, specify the type of cut required while using common terminology, such as:
- Kisscut: Through facestock to liner or to other layers if multi-ply construction
- Underscore: From beneath, through the liner and up to the facestock
- Thru cut: Through all layers, also called metal-to-metal or steel-to-steel
- Perforation: A cutting blade with equally spaced gaps or “ties”
- Ties: Specifically placed small gaps in a blade that leave an uncut connection or “hold” between parts
Machine Type: There can be unique characteristics between different machines that need to be taken into consideration when ordering a flexible die, such as:
- Width of the press
- Repeat of the magnetic cylinder
- The correct undercut needed to achieve precision cutting
- Any unique template that is customer specific or machine specific; an example would be pin placement on a die
Die Layout Specifications: Die manufacturers require the layout specification, and for standard label shapes such as rectangles, squares and circles, these can be supplied via a purchase order form that includes the specific information to the individual die line, such as:
- Label height
- Label width
- Repeat size of the cylinder
- Number of cavities across and around
- Size of the gaps between labels both across and around
- Gap (also known as undercut) of the magnetic cylinder to be used, if different from the industry standard
- For special label designs or layouts, an electronic file is required
Increasing Die Life
Die manufacturers also offer various options for increasing the life of a die, based on substrates and applications. Laser hardening has proven to be a very effective method of enhancing the wear characteristics of dies. This process hardens the steel of the cutting blade and provides durability without impairing die height tolerance and the die’s flexibility.
In addition, there are various surface treatments and coatings that can enhance the cutting characteristics of the flexible die. For example, glue-resistant coatings can be applied to the dies to significantly reduce the buildup of adhesive on the cutting blades. Chrome coatings also offer greater die life, especially when converting aggressive materials such as thermal face stocks.
In conclusion, it is important to remember that although your die suppliers are focused on providing you with a high-quality and extremely precise flexible die, they rely on the accuracy and quality of the information they are provided to achieve this. Providing clear, detailed information, along with an electronic file when required, will help expedite this process and ensure timely die delivery. A good die maker should also be viewed as a valuable resource of information, to advise on design decisions to achieve successful die cutting on presses.
About the Author: Jim Kissner has been the national sales manager for Kocher + Beck USA LP for five years. He has 32 years of industry experience.
Kocher + Beck is a world leader in rotary die technology, and a recognized complete systems provider to the label and envelope industry, with manufacturing plants in Germany, Russia, the UK and the US. The company offers high-quality, tight-tolerance flexible dies and magnetic cylinders, as well as solid rotary tools, print cylinders, hot stamp cylinders, TecScreen silk screen material, UR Precision winding technology, and the GapMaster precision adjustable anvil system.