Daetwyler Doctor Blades
Doctor blade life on modern flexo presses, with their combination anilox roller/doctor blade inking systems, is of great importance. The abrasive surface of ceramic anilox rollers requires minimal doctor blade pressure to prevent excessive blade and anilox wear. Equally important for blade life is the relationship between cell configurations (shape/count) and the blade tip thickness. MDC manufactures a wide variety of doctor blades to meet your specifactions and applications
Longlife
This is the doctor blade of choice for fighting print defects, such as streaking. It is commonly used for higher line screens where cleaner doctoring is required. This hardened-coating significantly lengthens blade life, therefore reduces the amount of steel contamination in the ink. Fewer blade changes are needed, resulting in reduced downtime and waste.
Soft
This blade is coated with a soft, corrosion-resistant nickel based material. The soft coating provides a more gentle contact point therefore reducing or eliminating the chance of roll scoring. The coating also heals small nicks in the blade edge, reducing lines and streaking as well as steel contamination of the ink.
Starlife
The hardened coating of this doctor blade is designed to resist wear when wiping abrasive inks, such as Titanium Dioxide white inks. The coating also reduces friction coefficients, which lowers blade and anilox wear. This smooth wearing coating maintains its edge to provide a long lasting, clean and sharp wipe.
Stableflex
A specialty doctor blade developed to prevent chatter marks, this tip configuration allows the blade to "ride" with the vibration (from older, unstable presses) or the bounce of the anilox roll when running at higher speeds (on newer, high-speed presses), giving a more precise metering of the ink film and resulting in a better quality print.
One-Step
The tip of this doctor blade maintains the same quality and characteristics of the lamella edge, but the design allows thicker ink to meter normally. The strengthened base decreases blade flex, creating consistent ink film metering without an ink hydroplaning effect behind the blade and eliminating or substanially lessening UV spitting
Standard
The award winning blade with a consistent tip thickness. The contact area remains unchanged throughout the life of the blade, therefore, no changes in tonal value or gradation occur due to wear. The special polished contact zones of these doctor blades guarantee a quick start-up without problems.
Metallic
These blades are used for Flexo and specialty printing application. A safe steel alternative, the Daetwyler Pro family of non-metallic blades are made of specially formulated materials designed to resist wear, prevent ink build-up and allow for safe handling. These specialty doctor blades are corrosion, crack and split resistant and can be custom cut-to-length or shipped in roll stock.
Chamber Doctor Blade Systems
There are two distinctly different blade systems; single Reverse-Angle blade system and the more commonly used enclosed doctor blade system. Angles on an enclosed system are pre-set and for single reverse-angle blade system the industry standard is approximately 30 to 35 degrees. Flat angles create greater contact area, requiring more doctor blade pressure to get a clean wipe. This increase n pressure creates excessive anilox and blade wear.
Reverse Angle Doctor Blades
Provide excellent printing and wiping. To obtain best results, the blade holder must be cleaned carefully and be in good condition. The doctor blade must be mounted absolutely straight and without waves. To prevent waves, tighten bolts in the blade holder from the center out. As always, minimal pressure is the key to successful printing
THE CORRECT PRESSURE
Minimum pressure ensures consistent blade wear and extended anilox life. The thinner the tip, the less pressure required to achieve a clean and brilliant printing result. It is recommended to use the same material on both sides of the chamber to eliminate uneven pressure. Increased pressure leads to a deflection of the doctor blade, resulting in a reduced angle and therefore in an increased contact area. The actual wiping is done by the back of the blade, leading to excessive anilox and blade wear.
THE INCORRECT PRESSURE
... Or excessive blade pressure creates free floating metal slivers that contaminate ink systems. When a hard particle becomes trapped between the deflected blade tip and the anilox, the particle rides there, effectively destroying rows of cells. These rows of cells appear as thin bands running the circumference of an anilox and are comonnly called score lines.
PROPER SYSTEM ALIGNMENT
For consistent ink metering, best print quality and optimized blade life, an enclosed chamber system requires perfect alignment (both horizontal and vertical) so that both blades have equal amounts of pressure. Incorrect alignment creates uneven blade pressure, blade wear and/or ink leakage. A common error that results from correcting alignment problems is excessive blade pressure. This excessive pressure will lead to a variety of previously discussed problems, like score lines
