Long lived, variable-delivery ink metering method, system and roller for keyless lithography

A method for metering a fluid from an outer surface of a metering roller with a surface-scraping doctor blade, comprising the steps of:

• providing the metering roller with a substantially cylindrical core having a core surface, with a wearable coating of a polymer material on said core surface, said coating having a predetermined thickness and having a predetermined percent by volume of substantially hard wear-resistant particles, said coating also having a surface which is said outer surface of the metering roller and having a plurality of cells in said coating, each of said cells having at least one straight cell wall oriented substantially perpendicular to said outer surface of the metering roller and having an open end at said outer surface of the roller, said open end forming a substantially sharp corner where said cell wall meets said outer surface;
• rotating said metering roller against the doctor blade, the doctor blade being held stationary;
• applying the fluid to the outer surface of the metering roller;
• scraping said outer surface of the metering roller with the doctor blade so that a metered quantity of fluid is provided;
• and
• providing a substantially constant ink delivery volume from said metering roller to a transfer roller in contact with said metering roller as long as a depth of each of said cells is greater than a shear-influenced region of each of said cells;
• wearing away said outer surface of the metering roller as the metering roller rotates and as the doctor blade scrapes against the outer surface with no substantially change in the amount of metered fluid provided as a result of the wearing away of the outer surface.