Letterpress printing is a special printing process that creates raised patterns or text on printed materials.

In letterpress printing, a metal template is first created, usually made of copper. This template is engraved with the pattern you want printed on the aluminum sign, which can be text, icons, or other design elements.

Then, during the printing process, the aluminum sign is placed on the printing machine, and a certain amount of pressure is added between the template and the aluminum sign. During the printing process, ink is transferred to the aluminum sign through the holes or raised parts of the template to form a raised pattern or text.

By adjusting the concave and convex depth of the template, you can control the height of the raised pattern on the aluminum sign. If you need to print a raised pattern of 0.1cm on the aluminum sign, you can use a template to achieve this requirement.