Variables that Impact Die Cutting.
Die-cutting is the process of using a tool to convert substrates utilizing the pressure-cut principle: during blade penetration, the material being cut is compressed and burst with the blade tip.
The objective of good die-cutting is a clean separation of the label face material, including the adhesive, from the carrier liner material without damaging the integrity of the silicone layer.
The quality of the cut depends on the material used, the design of the cutting unit, as well as the cutting die. Materials can vary from paper to film with different adhesives and liner thicknesses. Each of these variables will influence the geometry of the blade angles on the cutting tool. Printing inks can impact the process – as well as other variables such as die pressure and die station maintenance. RotoMetrics has integrated Electro Optic die-cutting technology to improve performance across the entire flexible die product offering, ensuring the best flexible die solution to meet the converter’s needs and specifications.
The following tricks and insights may help you optimize press performance right at the cutting station.
10 Tips on Correct Die Handling
Check the packing list and contents upon receipt of shipment
Keep the test certificate, trial cuts and cutting logs in a safe place. The cutting log will assist you with determining the running performance
Never lay the die down unprotected against the blade side
Clean the magnetic cylinder before mounting the die
Clean off ink and adhesive residue from anvil cylinder. Pressure the magnetic cylinder slowly to the anvil roll surface. Make sure there is sufficient pressure
Apply pressure to magnetic cylinder slowly. Lightest pressure is the best pressure for quality cutting. Use RotoMetrics Hydra Jacks to control and monitor even and consistent pressure. Do not tighten the pressure screws with tools. Too much or too little pressure can cause cutting blade damage. Note in cutting log the amount of pressure required on the new die and when die is removed at end of job to help monitor die life
Consider using an adjustable clearance anvil for extended die life. NOTE: an ACA will add life to a paper die, but will not make a dull film die sharp
Check and clean bearings, die blocks, press rollers and gears regularly, as well as the anvil roller
Clean the die after use. Consider adding RotoRepel to dies to minimize ink and adhesive build-up
Place the die in the rust preventative blue bag. Store die in a file hanger bag
Issue: Deep Die Strike in All Vertical Lines
Cause #1 : Liner material is thicker than assumed
Fixes: Install stepped down anvil cylinder. Re-set adjustable anvil cylinder. Consider an alternate material or die choice for the application.
Cause #2: Cutting die clearance gap is too small
Fixes: Check cutting anvil for wear. Replace and/or repair anvil roll if needed. Re-set adjustable anvil cylinder. Replace stepped-up anvil cylinder with smooth surfaced anvil cylinder. Audit mag cylinder condition for potential repair and maintenance.
Issue: Light Die Strike of All Vertical Lines or No Die Strike of Horizontal Lines.
Cause #1: Liner material is thinner than assumed
Fixes: Install stepped up anvil cylinder. Re-set adjustable anvil cylinder. Consider an alternate material or die choice for application.
Cause #2: Stepped down anvil cylinder installed
Fix: Install smooth surfaced anvil cylinder or stepped up anvil if needed.
Cause #3: Die is worn out or too low
Fixes: Order a new die. Install stepped up anvil cylinder for cutting paper.
Issue: Uneven cutting on left relative to right side.
Cause #1: Anvil cylinder wear or magnetic cylinder bearer issue
Fixes: Inspect bearer and anvil cylinder for replacement or repair. If large play in die mounting blocks replace blocks. Validate the correct gear is on the anvil and mag cylinder.
Issue: Labels Lifting with Web Matrix
Cause #1: Machine running too slow causes extensive lifting
Fix: Increase speed.
Cause #2: Inadequate web tension causes extensive lifting
Fix: Increase tension.
Cause #3: Waste matrix roll too loose causing extensive lifting
Fix: Change waste roll.
Cause #4: Large diameter stripping roll for matrix removal causing extensive lifting
Fix: Install a smaller diameter roll.
Cause #5: Die damage causes individual labels to lift
Fix: Utilize the EO/Rotometrics repair tool kit for flexible dies or order a new die if needed.
Cause#6: Magnetic cylinder damage causes individual labels to lift
Fix: Inspect and repair magnetic cylinder, or for short-term solution, reposition the die on the magnetic cylinder if possible.
Cause#7: Anvil roll damage causes individual labels to lift
Fix: Inspect and repair or replace anvil roll.