This article is part of the FLEXO FLAW FIXING series
What Is Misregistration?
One of the most common flexo printing flaws is misregistration, which occurs when the position of individual colors of the print image is inaccurate, resulting in a fuzzy picture or color fluctuations in tone images.
Print misregistration can be due to various faults, ranging from color pattern theft to design correctness. This fault causes unanticipated delays, wastage of substrate and ink, and wear and tear on the machines.
We’ve all had that experience when we’re painting, tracing, or gluing something and our hand slips, ruining our hard work.
That’s how to print misregistration feels. You must align your ink combinations on the substrate to produce the most significant print possible. A quarter of an inch of misregistration may drastically warp your image.
Flaws of Misregistration
Everything from color patterns to design correctness is affected. It also involves more downtime for troubleshooting. That means for your printing process:
- squandered time
- Substrate and ink waste
- Unnecessary machinery wear and tear
- Delays in print delivery
Examining your flexo print registration for these frequent problems can help your business save money and time.
What Are The Causes Of Misregistration problem In Flexo Printing?
If you’re encountering any level of flexo misregistration, one of the following scenarios is most likely:
- Plate mounting and centering errors
- Concentricity of the impression cylinder
- Condition of the cylinder/plate/sleeve
- Condition of the equipment
- Rollers that sit idle drag or spin erratically
- The malfunctioning online guide
- Web expansion or spreading out
- Substrate surface tension
- Wandering web
- Inadequate tolerances
- Plate Mounting And Centering Errors
The precise centerline of the printing cylinder, plate, or sleeve should be detected using cameras, mirrors, or the naked eye. The installation of the cylinder or sleeve must be in the same orientation and position.
- Concentricity Of The Impression Cylinder
The concentricity of your cylinder (a tolerance zone for the median points of a cylindrical or spherical item) must be as near to flawless as feasible. A dial indicator with accuracy should be installed on a magnetic base and used to make measurements from the center and end of the cylinder.
- Condition Of The Cylinder/Plate/Sleeve
Physical flaws and ink/grease accumulation can easily distort the photos you duplicate. Remove any filth from your plate, cylinder, and sleeve. Examine your printing surface for flaws such as cuts and indentations.
- Condition Of The Equipment
Flexo print misregistration can be due to missing gear teeth and general misalignment. Check that all of the gears are intact and appropriately positioned. The plate cylinder gear must be able to fit the cylinder journal with a tolerance. Check that the packs are free of extra grease and other materials.
- Rollers That Sit Idle Drag Or Spin Erratically
Dragging or unstable rotation prevents proper ink transfer. Your inked image carrier will not make suitable contact with the substrate at the appropriate time and location.
- The Malfunctioning Online Guide
The web guide is a closed-loop system that incorporates the following components:
- Actuating Cylinder
The sensor sends error indications to the controller, which allows it to modify the velocity difference throughout the web. Correct sensor placement is crucial.
- Web Expansion Or Spreading Out
As layers in the picture, the web width steadily increases from station to station, creating print misregistration. You can utilize prepress software or bustle wheels to compensate for the expansion.
- Substrate Surface Tension
Any lateral movement of your site will result in print problems. To keep your substrate stable, adjust the tension at the splicer.
- Wandering Web
If the surface tension is incorrect, it will not absorb and distribute pressure effectively to transfer ink from the image carrier. Maintain an adequate degree of stress so that the image carrier touches the substrate evenly and uniformly.
- 10.Inadequate Tolerances
Because of register changes, two letters, words, or artwork printed adjacent to one other may overlap or misalign. Make sure that pictures of various hues are more than twice the image trap dimension apart.
Solutions To Prevent Misregistration Problem In Flexo Printing
- Place the printed forms back in the register. Examine the form mounting and form mounting equipment and the form thickness. Examine the relief height of the forme and any deformation. Check the thickness of the mounting tape.
- Adjust the web tension control about the substrate.
- Ensure that the web guide rollers are parallel and that the pressure setting is uniform across the web width.
- Lower the dryer temperatures.
- Center the compensating rollers of the side and longitudinal registers before manually adjusting the print register.
- Replace or oil the idle roller bearings.
- Adjust the press.
- Change the driving gear.
However, even it’s difficult and irritating to resolve these challenges. It is critical to determine what is not registering and why. In general, seek the misregistered component in three places: over the web, across the web, and mounting cameras:
Misregistration Across The Web
To Combat Misregistration in Printing Misregistration often occurs on the internet. When this happens, it’s conceivable that the plates line up but not the sleeves.
Begin by ensuring that your sleeve is correctly attached to the mandrel; if everything appears to be in order, it might be a faulty web guide, where the internal sensor has failed and is erroneously reporting faults.
These mistakes are due to sleeve, which means that all of your plates will line up; nevertheless, you will still have misregistration on the web.
Misregistration On The Internet
When dealing with online misregistration, it is critical to ensure that your gearing is proper. Attempting to run a sleeve with the wrong gear sizes can significantly affect print alignment. Furthermore, examine the quality and wear on your gears because even one misaligned, damaged, or bent piece of equipment can produce significant errors in your prints.
If your gears are twisted, fractured, or otherwise damaged, the quality of your prints will deteriorate with time.
Mounting Cameras To Combat Misregistration problem In flexo Printing
Flexo press operators are well aware of the need for mounting cameras. While you may believe your cameras will never be handled, bumped, or relocated, mistakes are unavoidable, and it’s critical to verify their alignment and guarantee.
Identifying the source of your misregistration is simply the first step; correcting the problem. On the other hand, it can be overwhelming owing to the abundance of press sites where misregistration can occur.
By keeping these factors in mind, you can avoid ending up with too dark or vibrant prints.