In today’s competitive manufacturing landscape, acquiring a pre-owned CNC machine is not simply a cost-saving decision—it is a strategic investment. Machines like the DMG MORI CLX 750 CNC Turning Center, manufactured in Germany, represent high-end engineering designed for precision, durability, and long-term productivity.

However, purchasing a used machine without proper technical evaluation can introduce significant risks. This guide provides a professional, engineering-level checklist for evaluating a secondhand CLX 750—from the factory floor to your workshop.

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1. Understanding the Machine: CLX 750 Technical Profile

Before evaluating condition, you must fully understand what the machine is capable of.

Key Technical Specifications

• Maximum turning diameter: up to Ø700 mm
• Turning length: approx. 1,290 mm
• Workpiece weight capacity: up to 600 kg
• Main spindle power: ~46–48 kW
• Torque: up to 2,000 Nm
• Max spindle speed: ~2,000 rpm
• Bar capacity: Ø127 mm
• Y-axis travel: ±80 mm (optional)
• Turret: 12-position VDI 50

Engineering Highlights

• Integrated counter spindle for full 6-sided machining
• High rigidity 45° slant bed casting
• Linear guideways for dynamic accuracy
• Compatibility with SIEMENS or FANUC control systems
• Built-in IoT connectivity for digital manufacturing

These features position the CLX 750 as a heavy-duty, high-precision universal turning center, ideal for shafts, large components, and complex parts.

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2. Mechanical Condition Assessment

Visual Inspection & Structural Integrity

What to Check:

• Bed casting condition
  • Look for cracks, deformation, or poor repairs
• Guideways (X, Z, Y axes)
  • Excessive wear → loss of precision
• Turret indexing accuracy
  • Misalignment indicates backlash or servo issues
• Chuck and spindle nose condition
  • Check runout and clamping reliability

Critical Insight

A worn mechanical structure cannot be economically restored—even if electronics are upgraded. Structural rigidity is the core value of a used CNC machine.

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3. Spindle & Drive System Evaluation

The spindle is the “heart” of the CLX 750.

Key Tests:

• Spindle runout measurement (µm level)
• Vibration analysis at different RPM ranges
• Thermal stability after long operation
• Load test under cutting conditions

Red Flags:

• Abnormal noise at high torque (2,000 Nm class machines must run smoothly)
• Overheating bearings
• Reduced torque under load

Remember: A spindle rebuild on a machine of this class can cost tens of thousands of euros.

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4. CNC Control & Electrical System

Control Panel & Automation Check

Evaluate:

• Control type: SIEMENS or FANUC
• Software version and upgrade availability
• PLC logic integrity
• Alarm history logs

Important Checks:

• Axis positioning accuracy (ballbar test recommended)
• Servo drive condition
• Electrical cabinet cleanliness (dust = overheating risk)

Older software may limit integration with modern Industry 4.0 systems.

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5. Accuracy & Precision Testing

Mandatory Tests:

• Ballbar test (circular interpolation accuracy)
• Laser calibration (axis positioning error)
• Repeatability test (micron-level consistency)

The CLX 750 is designed for high precision machining with direct measuring systems , so deviations from specification indicate wear or calibration loss.

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6. Tooling, Options & Automation Value

A used CNC machine’s value is heavily influenced by included options.

High-Value Options:

• Y-axis (±80 mm capability)
• Counter spindle (complete machining)
• Driven tools (live tooling)
• Bar feeder or automation interface
• Steady rest (for long shafts up to Ø430 mm)

A fully equipped CLX 750 can be 2–3x more valuable than a basic version.

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7. Maintenance History & Usage Profile

Request Documentation:

• Maintenance logs
• Service records (especially spindle and drives)
• Operating hours (spindle hours vs. machine hours)

Usage Scenarios:

Usage Type	Impact
Light precision work	Low wear
Heavy roughing (steel shafts)	High mechanical stress
24/7 production	Accelerated fatigue

Machines used for heavy-duty shaft machining experience significantly more stress.

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8. Test Cutting: The Final Decision Step

Never buy without a live cutting test.

Recommended Test:

• Material: Steel (e.g., C45 or equivalent)
• Operation: Rough + finish turning
• Measure:
  • Surface finish (Ra value)
  • Dimensional accuracy
  • Tool wear behavior

This is the only way to validate real-world performance, not just specifications.

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9. Transportation & Installation Considerations

• Machine footprint: approx. 8.9 m²
• Weight: heavy-duty industrial class
• Check:
  • Foundation requirements
  • Power supply compatibility
  • Rigging and transport costs

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10. Final Risk Evaluation Checklist

Before Purchase, Confirm:

✔ Mechanical integrity (bed, guides, turret)
✔ Spindle condition (noise, heat, runout)
✔ CNC control reliability
✔ Precision test results
✔ Included tooling and options
✔ Verified maintenance history
✔ Successful test cutting

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Conclusion

The DMG MORI CLX 750 CNC Turning Center is a premium German-Japan-engineered turning center capable of heavy-duty machining with exceptional precision and flexibility. When properly evaluated, a pre-owned unit can deliver near-new performance at a significantly reduced investment cost.

However, the key difference between a profitable purchase and a costly mistake lies in technical due diligence.

A disciplined evaluation—combining mechanical inspection, precision testing, and real cutting validation—ensures that your transition from factory floor to your workshop is both successful and profitable.