The basic principal behind the pad printing technology is that the flexible rubber silicon pad picks up the image from the etched surface of ink flooded cliché and than transfer it to the component, where printing is required.
1st step- Flooding of the metal surface of plate through forward movement of ink container.
2nd Step-Backward movement of the ink container and blade attached to it. During this movement, the blade withdraws ink from the plate, leaving ink in the etched area.
3rd Step - Downward movement of pad on the plate, thus picking up the impression of the etched image.
4th Step - Forward and downward movement of pad on the component and thus transferring the image picked up from the etched surface.
For more information you can visit http://spinksworld.com/
It is quite difficult to make a prudent decision to select a particular pad printer when you have variety of options available in front of you. If you are clear with the process design and requirement details, then of course the selection becomes easy.