Which lines are established on the machine base for determining the exact position of the machine?

The correct answer is center lines. Center lines are critical in machine installation as they provide a reference point for aligning the machine in relation to other components or structures in the facility. By establishing center lines on the machine base, millwrights can ensure that the machine is installed in the precise position required for optimal operation. This alignment is essential to avoid issues such as misalignment that could lead to excessive wear, vibration, or failure of the machinery over time.

Other terms like bench lines typically refer to reference lines used for measurements and setups, which may not be specifically related to the machine's operational center. Permanent lines might imply lines drawn for long-term references but do not specifically address the alignment of the machinery. Foundation lines are associated with the installation of the foundation itself, providing a level reference but not necessarily focusing on the exact placement of the machine on that foundation. Thus, center lines are specifically designed for achieving accurate positioning crucial for operational integrity.