What is indicated by center lines in technical drawings?

Center lines in technical drawings are crucial for conveying information about symmetry and alignment within a design. They serve as reference lines that indicate the midpoints or axes of shapes, which is essential when symmetrical features are involved, such as in circular or symmetric components. By establishing a clear center line, it helps in understanding how different parts of the assembly relate to one another, ensuring components are positioned correctly.

These lines effectively communicate where parts should align, especially in assemblies where balance or symmetrical relationships are critical for function and aesthetics. They also assist in the layout of holes, cuts, or other features that are designed symmetrically about the center. Thus, the presence of a center line helps in maintaining accurate alignment over the visual representation and actual assembly of parts, guiding the manufacturing process.