FAQ About Doctor Blade Suppliers and Flexo Printing

Allison Systems Corporation is one of the leading doctor blade suppliers in the nation. Here we will address some common questions about metal and plastic blades, in addition to information about flexo printing.

What Is The Purpose Of A Doctor Blade?

A doctor blade is typically used on gravure and flexographic printing presses and coaters. It wipes the surface of an engraved cylinder clean so that the only remaining ink or coating is within the engraved cells of the cylinder. That ink is then transferred to the web.

Why Is It Called A Doctor Blade?

In early letterpress equipment, operators used blades to wipe the “ductor” rolls. We believe that over time, the word “ductor” morphed into “doctor.”

How Do Doctor Blades Work?

Doctor blades are wiped on the surface with enough pressure to remove all the ink or coating.

How Long Does A Doctor Blade Last?

There is no easy answer. Doctor blades can last anywhere from a few hours to several weeks, depending on the operating parameters of their specific application.

How Do I Install A Doctor Blade That Has A Bevel Or Lamella Profile?

A common misconception is that the bevel or lamella profile runs against the surface it is wiping. However, the opposite is true; the bevel or lamella profile should always face away from the wiped surface.

How Much Pressure Should I Apply To The Doctor Blade?

Apply enough pressure for the doctor blade to wipe the entire surface cleanly, but not so much that it over-deflects to create defects in the product.

Do I Have To Use Stainless Steel Blades With Water-Based Inks and Coatings?

In most cases, no. Many inks and coatings will likely not corrode carbon or tool steel blades, especially if the blade is not used on multiple runs or there aren’t long periods of downtime between runs using the same blade. Highly corrosive water-based inks and coatings will likely require stainless steel if you use metal blades.

What Are End Seals For Flexo Printing?

End seals are typically foam or felt dam-like devices at each end of a flexographic chambered inker. The end seal prevents ink from flowing out of the ends of the chamber.

Important Things To Know When Ordering Flexo End Seals

If your end seals are working well, re-order by providing the part number to your supplier. If the end seals need improvement, you may need to provide a new sample of the current end seal and operational parameters like anilox roll diameter, ink system information, run speeds, and the nature of improvements desired.