We've all had that moment when we're painting, tracing, or gluing something and in our intense concentration, our hand slips, marring our precious work.
That's what print misregistration is like. To get the best possible print, the alignment of your ink combinations on the substrate must be precise. Misregistration by the tiniest fraction of an inch can completely skew your print.
It impacts everything from color patterns to design accuracy. It also means downtime for troubleshooting. For your process, that means:
- Wasted time
- Wasted substrate and ink
- Unnecessary wear and tear on machinery
- Delays in delivering prints
Assessing your flexo print registration for these common causes can help your operation save money and undue hassle.
10 Common Causes of Print Misregistration
If you're experiencing print misregistration, one of the following circumstances is probably occurring:
- Inaccurate plate mounting / centering
- Impression cylinder concentricity
- Cylinder/ plate/ sleeve condition
- Gear condition
- Idle rollers drag or rotate irregularly
- Malfunctioning web guide
- Web growth or fanning out
- Wandering web
- Substrate surface tension
- Incorrect tolerances
Here's how to troubleshoot and fix these issues:
1. Inaccurate Plate Mounting/Centering
Whether using cameras, mirrors, or the naked eye, the exact centerline of the printing cylinder, plate, or sleeve should be identified. The cylinder or sleeve must be mounted in the same location and orientation.
2. Impression Cylinder Concentricity
Your cylinder’s concentricity (a tolerance zone for the median points of a cylindrical or spherical part) must be close to perfect as possible. A dial indicator capable of showing errors down to 0.0001 inches should be mounted on a magnetic base and used to produce measurements from the middle and near each end of the cylinder.
Generally accepted flexo printing guidelines say total concentricity run out shouldn’t be more than about 0.0005 inches.
3. Cylinder/Plate/Sleeve Condition
Physical defects and ink/grease buildup can easily skew your reproduced images. Clean your plate, cylinder, and sleeve to remove any grime. Inspect your printing surface for damage like cuts and indentations.
4. Gear Condition
Missing gear teeth and general gear misalignment can create print misregistration issues. Make sure all gears are intact and positioned properly. The plate cylinder gear must fit the cylinder journal with a tolerance no greater than 0.002 inches of error.
Also make sure the gears are clear of excess grease and foreign materials.
5. Idle Rollers Drag or Rotate Irregularly
Dragging or wobbly rotation makes accurate ink transfer impossible. Your inked image carrier will not be making contact with the substrate at the proper time and place.
6. Malfunctioning Web Guide
The web guide is a closed-loop system, which includes:
- Actuating cylinder
The sensor gives error signals to the controller to adjust velocity differential across the web. Correct sensor prepositioning is critical.
7. Web Growth or Fanning Out
The web width gradually grows as it travels from one station to the next, causing print misregistration as images are applied in layers. You can use prepress software or bustle wheels to compensate for the growth.
8. Wandering Web
Any lateral movement of your web will cause print issues. Manipulate the tension at the splicer to hold your substrate steady.
9. Substrate Surface Tension
If surface tension is off, it will not correctly absorb and distribute pressure to transfer ink from the image carrier. Keep tension at an appropriate level so the image carrier contacts the substrate evenly and uniformly.
10. Incorrect Tolerances
Register shifts can cause two letters, words, or designs printed next to each other to overlap or misalign. Make sure images with different colors are more than twice the image trap dimension from each other.
Troubleshooting Flexo Print Misregistration and Other Defects
Much can go wrong on a printing press, but making sure mechanical components and pre-press calibrations are correct will avoid costly print misregistration errors.
If you’re having issues troubleshooting your press, check out our free guide to diagnosing printing defects!
Editor's Note: This blog post was originally published on November 22, 2017 and was recently updated.