| Workpiece Capacity | Maximum swing over bed | 450–800 mm for general production work | Choose a machine with at least 20–30% more swing than the largest planned workpiece to allow for fixtures, tool clearance, and safe chip evacuation. |
| Workpiece Capacity | Maximum turning diameter over cross slide | 250–500 mm for medium-duty applications | This value is often more useful than swing over the bed because it reflects the diameter available during actual tool movement. |
| Workpiece Capacity | Distance between centres | 500–1,500 mm | Select a centre distance longer than the maximum part length, including chucking allowance and support from a tailstock or steady rest. |
| Spindle System | Spindle bore | 52–105 mm for common bar and shaft work | The bore should accommodate the largest bar stock or workholding draw tube required by the production range. A larger bore can improve flexibility but may increase spindle mass and cost. |
| Spindle System | Spindle speed range | 30–4,000 rpm for general-purpose turning | Low-speed torque is important for large diameters and heavy cuts, while higher speed supports small-diameter parts and finishing operations. |
| Spindle System | Spindle motor power | 7.5–22 kW for medium-duty production | Compare continuous and short-time power ratings, not only the peak value. Confirm that available torque matches the materials, cutting depths, and insert grades used in production. |
| Axis Performance | X-axis travel | 180–350 mm | Verify that the travel covers the required turning diameter while leaving sufficient clearance for the turret, toolholders, chuck, and part geometry. |
| Axis Performance | Z-axis travel | 400–1,200 mm | Allow extra travel for facing, grooving, threading run-outs, workholding, and future part-size changes. |
| Axis Performance | Rapid traverse rate | 15–30 m/min | Higher rapid speed can reduce non-cutting time, but evaluate acceleration, positioning stability, and actual cycle-time data rather than speed alone. |
| Accuracy | Positioning accuracy | Approximately ±0.005 to ±0.010 mm per axis | Request a documented measurement method and test length. Accuracy should be evaluated together with thermal stability, calibration practices, and machine foundation quality. |
| Accuracy | Positioning repeatability | Approximately ±0.002 to ±0.005 mm per axis | Repeatability is critical for consistent batch production. Ask for test results under operating conditions and check performance after warm-up. |
| Machine Structure | Bed construction and guideways | Rigid slant bed with hardened linear or box guideways | A rigid bed helps control vibration and taper during heavy cuts. Inspect guideway protection, lubrication access, and resistance to chips and coolant. |
| Workholding | Chuck size and type | 200–315 mm hydraulic three-jaw chuck for general work | Confirm chuck bore, gripping range, clamping force, jaw change time, and compatibility with the spindle nose and planned part shapes. |
| Tooling | Turret capacity | 8–12 stations for standard turning; 12–16 for complex work | Consider the number of operations, duplicate tools for unattended production, driven-tool requirements, indexing time, and toolholder availability. |
| Tooling | Live tooling capability | Optional for turning-only work; recommended for drilling, milling, and off-centre features | Check live-tool power, maximum speed, C-axis resolution, coolant delivery, and whether the machine can complete secondary operations without an additional setup. |
| Control and Programming | CNC control functions | Conversational programming, standard G-code, tool compensation, and rigid tapping | Confirm memory capacity, USB or network transfer, simulation, tool-life management, probing support, alarm diagnostics, and compatibility with existing programs. |
| Production Efficiency | Chip and coolant management | Enclosed work area with chip conveyor and filtered coolant system | Evaluate conveyor type, chip handling for long-string materials, coolant tank capacity, filtration, washdown coverage, and access for cleaning and maintenance. |
| Safety and Compliance | Guarding and interlocks | Fully enclosed guarding with monitored door interlocks | Check emergency stops, interlock performance, chuck clamping confirmation, spindle-speed monitoring, visibility, lighting, and compliance with applicable local regulations. |
| Installation | Footprint and power requirement | Typically 2.5–5.5 m machine length; three-phase industrial power | Confirm floor loading, foundation requirements, electrical capacity, compressed air, coolant ventilation, access routes, and space for loading and maintenance. |
| Lifecycle Value | Serviceability and operating cost | Accessible lubrication, standard consumables, and documented preventive maintenance | Assess spare-parts availability, technical support response, warranty terms, energy consumption, training, maintenance intervals, and the total cost over the expected service life. |