1) Machine Overview

The FANUC Robocut α-1iB Wire EDM is a precision electrical discharge machining system built for fine contouring, mold manufacturing, and high-accuracy tooling.
Manufactured in Japan, it’s known for its stable discharge control, rigid cast-iron frame, and CNC 31i-WB control, enabling micron-level cutting accuracy on hardened steel, carbide, titanium, and other conductive materials.

With a robust automatic wire threading system (AWT), submerged cutting capability, and intelligent thermal control, the α-1iB remains one of the most sought-after mid-size wire EDMs in its class.

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2) Key Technical Specifications

Feature	Specification	What to Verify
Workpiece Capacity	800 × 700 × 250 mm, 1000 kg	Confirm table flatness and tank sealing
X / Y / Z Travel	370 / 270 / 255 mm	Move full stroke, check smoothness
U / V Travel	±60 mm	Confirm taper motion and parallelism
Wire Diameter	0.1 – 0.3 mm	Check wire guide alignment and wear
Wire Feed Rate	2–12 m/min	Verify feed motor function
Max Taper Angle	±15° / 100 mm	Test alignment and compensation accuracy
Generator Type	FANUC α-i Series Digital Pulse Generator	Inspect spark stability and waveform display
Control	FANUC 31i-WB CNC	Boot time, alarm log, and parameter integrity
Dielectric Tank Capacity	630 L	Check for leaks and water flow clarity

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3) Mechanical & Structural Integrity

• Machine Bed and Columns:
  Verify no cracks, rust, or coolant corrosion; the bed should remain level and vibration-free.
• Work Tank & Cover:
  Check the stainless steel tank for dents or leaks. Inspect the sliding doors and automatic rise/lower mechanism.
• Linear Guides and Ball Screws:
  Move each axis across the full stroke — feel for uniform motion. Listen for servo noise indicating wear or contamination.
• Table Flatness:
  Place a precision straightedge on the table surface; deviation must be ≤ 0.005 mm per 300 mm.
• Dielectric System:
  Examine the pump, filters, and resin bottles — water should remain clear and resistivity between 15–20 MΩ·cm for optimal discharge.

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4) Wire Drive & Automatic Threading System (AWT)

Component	Inspection Focus	Acceptable Condition
Upper & Lower Guides	Ceramic or ruby inserts	Free of chipping or wear
Wire Drive Rollers	Surface finish	Smooth, no grooves
Tensioner Assembly	Pressure consistency	Within ±5 %
AWT System	Threading speed & reliability	≥ 90 % success rate
Wire Feeder Nozzle Alignment	Optical inspection	Concentric with guides
Wire Contact Assembly	Cleanliness	No carbon buildup

Tip: A worn or misaligned wire feed path is the #1 cause of cutting inaccuracy on used EDMs. Always request a threading test using a 0.25 mm brass wire before purchase.

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5) Generator & Discharge Performance

Parameter	Typical Value	Evaluation
Discharge Stability	Continuous spark at low current	Observe live waveform on screen
Peak Current Control	Adaptive feedback active	Confirm via diagnostics menu
Pulse Width / Off-time	Stable under varying gaps	No arc instability
Wire Break Frequency	≤ 1 break per 4 hours (typical)	Measure during sample cut
Surface Finish Capability	≤ Ra 0.2 µm	Run fine finish cycle on tool steel
Corner Accuracy	≤ ±0.003 mm	Square test cut validation

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6) CNC Control & Electronics

• FANUC 31i-WB Controller:
  Boot-up time < 60 seconds; no “SRVO-” or “PARA-” alarms.
  Check memory card slot, USB, and Ethernet ports.
• Screen & Input Devices:
  Verify touchscreen calibration, hard key response, and CRT/LCD brightness.
• Alarm History:
  Review logs for repeated servo faults, discharge short-circuit errors, or AWT jams.
• Parameter Backups:
  Ensure NC parameters, macros, and pitch error compensation tables are backed up via CF card.
• Servo Drives & Fans:
  Check cabinet temperature (< 40°C during run); all fans must operate.

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7) Motion & Accuracy Verification

Test	Method	Acceptable Limit
Positioning Accuracy (X/Y)	Laser interferometer	±0.002 mm / 300 mm
Repeatability	10× same path test	±0.0015 mm
Squareness (X–Y)	Test cut block	≤ 0.003 mm
Taper Accuracy (U/V)	±15° test on 100 mm	≤ 0.01 mm
Wire Offset Compensation	Software check	Corrected automatically
Cutting Speed Test	100 mm steel block	≥ 100 mm²/min typical

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8) Dielectric System & Filtration

• Water Cleanliness:
  Measure resistivity and temperature. High contamination reduces cut stability.
• Filters & Resin Bottles:
  Replace every 150–200 hours of cutting. Check flow meters and return lines.
• Chiller / Heat Exchanger:
  Maintain dielectric temperature ±0.5 °C from ambient for precision cuts.
• Pump Sound / Flow:
  No cavitation or noise — consistent delivery rate required.
• Workpiece Flushing:
  Verify top and bottom nozzles deliver uniform pressure and coverage.

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9) Typical Wear & Failure Points

• Worn Wire Guides: Leads to taper and accuracy drift.
• AWT Line Moisture: Causes failed threading cycles.
• Clogged Filters / Resin: Leads to unstable spark gap and slow cutting.
• Servo Amplifier Errors: “SV0361” or “SV0382” faults — possible axis encoder failure.
• Pump Cavitation: Low dielectric flow and inconsistent pressure.
• Tank Seal Leakage: Water seepage at door gaskets or drain.

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10) Documentation & Verification to Request

Document	Purpose
OEM Build Sheet	Confirms model, travel, and configuration
Machine Usage Hours	Determines pump and AWT life expectancy
Calibration Report	Proves geometry and positioning accuracy
Preventive Maintenance Log	Validates filter, pump, and chiller service
FANUC Control Backup	Ensures parameter recovery after power loss
Electrical & Hydraulic Schematics	Required for diagnostics
Test Cut Certificate	Confirms current cutting accuracy

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11) Acceptance Criteria Summary

Parameter	Target Value	Verification
Positioning Accuracy	±0.002 mm	Laser calibration
Repeatability	±0.0015 mm	10× cycle test
Surface Finish (Ra)	≤ 0.2 µm	Sample cut
Squareness	≤ 0.003 mm	Test block
Wire Break Frequency	≤ 1 / 4 hr	Continuous cutting test
AWT Success Rate	≥ 90 %	Threading cycle
Water Resistivity	≥ 15 MΩ·cm	Conductivity meter
Noise Level	< 70 dB(A)	Under load
Dielectric Temp. Stability	±0.5 °C	Chiller readout

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12) High-Value Features That Add Worth

• FANUC Auto Wire Threading (AWT) with Jet Assist
• Digital Generator (α-i Series) for ultra-stable discharge control
• High-Speed Resin and Filter Unit Upgrade
• Built-in Chiller and Temperature-Controlled Dielectric Tank
• Auto Power Control (APC) for consistent rough-to-finish transitions
• Macro Libraries & 3D Offset Functions
• Glass Scale Feedback (on high-precision variants)
• Low Power Consumption Mode (ECO Function)

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13) Red Flags — Avoid If

• Frequent wire break alarms or erratic spark pattern.
• Damaged AWT unit or missing wire path components.
• Leaking dielectric tank or faulty pump.
• Worn or cracked ceramic wire guides.
• Missing FANUC backup files or locked CNC parameters.
• Excessive rust, corrosion, or resin contamination inside tank.
• Evidence of oil mixing in dielectric water.

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14) Buyer’s Quick Checklist

✅ Serial number & year of manufacture verified
✅ Control boots cleanly without alarms
✅ Wire guides and rollers in good condition
✅ AWT test completed successfully
✅ Sample cut accuracy within ±0.002 mm
✅ Chiller maintains stable temperature
✅ Filters and resin recently replaced
✅ Electrical cabinet clean and dry
✅ Manuals, backup files, and calibration report included

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Pro Tip

A well-maintained FANUC Robocut α-1iB should demonstrate consistent spark stability, smooth wire feeding, and precise cutting even during long unattended runs.
Always request a live threading and test cut demonstration on hardened steel.
Machines with recent dielectric system overhauls, generator calibration, and AWT service records offer the best reliability and resale value.