The Mitsubishi MAF-RS150C is a heavy-duty, high-precision horizontal boring mill widely used across energy, aerospace, mold & die, construction machinery, and large-component machining. Because these machines were built with exceptional Japanese engineering standards, well-maintained units can deliver decades of accuracy and reliability.
However, the value of a used unit can vary greatly based on condition, controls, usage environment, and retrofit history. Below are the key expert recommendations to ensure a successful purchase.

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1. Verify the Mechanical Health of the Main Structures

Spindle Condition

• Request spindle vibration analysis and bearing noise checks.
• Verify spindle taper runout with a test bar (<0.005 mm is desirable).
• Ask if the spindle has been rebuilt and by whom (factory rebuilds are preferred).

Box Ways / Linear Guideways

• MAF-RS series machines often use hardened box ways for rigidity.
• Inspect for:
  • scoring
  • uneven wear patterns
  • loss of lubrication
• If resurfacing was performed, request documentation.

Ram & Quill Condition

• The RS150C is known for its long Z/W axis ram stroke.
• Check for:
  • quill play
  • deflection at full extension
  • backlash or worn gibs
• A laser or ballbar report of the Z/W axes is recommended.

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2. Confirm the Accuracy of Travel Axes

Geometric Accuracy Tests

Request recent reports for:

• Laser calibration (X/Y/Z/W/B axes)
• Ballbar circularity tests
• Leveling and straightness measurements

Any deviation may indicate:

• heavy usage
• machine crashes
• misalignment
• lack of preventive maintenance

Repairs can be expensive on large boring mills, so data is crucial.

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3. Evaluate the CNC Control and Electronic Health

Control Version

Many units originally came with Mitsubishi Meldas controls. Ask:

• Has the control been upgraded?
• Are spare boards available?
• Are parameters and backups included?

Servo & Drive System

• Inspect servo drives, amplifiers, feedback encoders.
• Ensure axes home correctly without alarms.
• Check for discontinued components—availability affects long-term serviceability.

Electrical Cabinet

Look for:

• overheating marks
• non-OEM wiring
• dirty filters
• missing documentation

A clean cabinet often reflects disciplined maintenance.

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4. Evaluate the Machine’s Work History

Hours and Type of Work

The RS150C is used for:

• large steel components
• mold bases
• gearbox housings
• energy and construction equipment

Machines used for heavy roughing or continuous 3-shift industrial work may show more wear.

Ask for:

• total operational hours
• spindle on-time
• maintenance logs
• any collision history

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5. Inspect the Table, B-Axis & Rotary Accuracy

Table Condition

• Inspect for scoring, gouges, or weld repairs.
• Check positioning repeatability.

B-Axis Rotary Table (if equipped)

• Confirm indexing accuracy and clamping torque.
• Verify hydraulic clamping pressure levels.
• Inspect rotary surfaces for damage or excessive backlash.

Rotary table rebuilds are costly—data is essential.

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6. Hydraulics, Lubrication & Cooling Systems

Hydraulic System

• Check pump noise, pressure stability, and leak points.
• Ask if seals or valves have been replaced.

Lubrication System

• Verify metering units function correctly.
• Inspect for dry ways, clogged lines, or bypassed systems.

Coolant / Chip Removal

• Evaluate coolant tank condition & filtration.
• Inspect chip conveyors, augers, flushing pumps.

A neglected fluid system accelerates wear on expensive components.

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7. Tooling, Accessories & Optional Equipment

A well-equipped used RS150C dramatically increases value:

Desirable Options

• right-angle heads
• extended boring bars
• facing heads
• spindle coolant
• high-pressure machining center
• rotary tables
• manual and CNC probes
• floor plates
• tool holders (ISO/NMTB/CAT)
• chip conveyor + filtration system

Check Compatibility

Make sure accessories match:

• spindle taper
• quill diameter
• table capacity

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8. Confirm Rigging, Installation, and After-Sales Support

These machines typically weigh over 40,000–60,000 kg depending on configuration.

Ask About:

• original foundation specifications
• trucking restrictions
• disassembly & reassembly requirements
• leveling procedures
• recommended Mitsubishi service technicians

Incorrect installation can significantly degrade accuracy.

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9. Request a Full Cut Demonstration Before Purchase

A live cutting test tells the real story. Evaluate:

• surface finish
• spindle load during roughing
• axis noise during rapid movement
• actual vs. programmed dimensions
• stability at long ram extension

Recording videos and measurements is highly recommended.

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10. Determine the True Market Value

Pricing depends on:

• year of manufacture
• spindle taper & travel lengths
• accessories included
• mechanical accuracy reports
• spindle rebuild history
• condition of electronics
• geographic location and transport cost

Well-maintained RS150C units can command premium pricing due to their robust Japanese build quality and long service life.

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Conclusion: Buy Based on Verified Data, Not Assumptions

The Mitsubishi MAF-RS150C is a world-class horizontal boring mill. A second-hand unit can offer enormous value if chosen carefully with full accuracy reports, spindle data, machine history, and proper inspection.

Industry experts always recommend:

• detailed mechanical inspection
• control and electrical evaluation
• documented accuracy verification
• demonstration under load
• confirmation of spare parts availability

By following the above guidelines, you can confidently acquire a used Mitsubishi MAF-RS150C that performs like a top-tier production asset while preserving capital.