Round tensile specimens are produced on CNC lathes through turning, where the stock material rotates while the tool shapes it into a defined diameter and gauge length. This setup is suitable for rods, bars, or machined blanks.

Flat specimens, on the other hand, are made by milling, where the cutting tool removes material from a fixed sheet or plate to form a flat, dog-bone shape. These are often used for thin metals, plastics, or layered materials.

Both methods serve different testing needs: round specimens are better for materials that require even stress distribution during testing, while flat specimens are used when the focus is on surface layers or sheet performance.