When sourcing a VMC, you must prioritize the spindle speed (RPM) and taper type (e.g., BT40 or BT50), as these determine the material removal rate and tool compatibility. Additionally, evaluate the positioning accuracy and repeatability (ideally within ±0.005mm), the number of tool stations in the Automatic Tool Changer (ATC), and the table load capacity to ensure it meets your specific workpiece requirements. High-quality machines should feature linear guideways for speed or box ways for heavy-duty cutting rigidity.