When buying a used Makino EDNC-15 (or similar Makino sinker / ram EDM), the risks are high—EDM machines combine high precision, delicate electronics, power supply systems, and fluid systems. Below is a detailed “red flag checklist” and professional tips to help you avoid costly mistakes.

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What “Good / Healthy” Looks Like — Benchmark Specs & Design Reference

Before you inspect, you need to know what the “ideal” Makino EDNC-15 offers, so you can spot exaggerations or hidden depreciation. From Makino’s published data:

• The EDNC-15 is part of Makino’s EDNC Series of sinker (ram) EDM machines.
• Key specs include:

  • Travel (X / Y / Z): 1,500 × 700 × 500 mm (standard)
  • Optional extended Z to 800 mm in some configurations (HS-Rib jump capability)
  • Rapid traverse / jump (non-cut) speeds: up to 5,000 mm/min
  • Maximum workpiece weight: 10,000 kg (22,000 lbs)
  • ATC (automatic tool changer) options: 8, 16, or 32 station
  • Dielectric tank size: 2,500 × 1,400 × 800 mm (as built into base cast)
  • Max electrode weight: 100 kg

• Design features to watch:
    * Stationary worktable, moving head (ram) design improves stability under heavy part loads.
    * Integrated dielectric reservoir built into the machine base (to reduce thermal distortion)
    * The EDNC series supports Makino’s “Hyper-i” control environment, SuperSpark / HyperCut / HS-Rib jump modes etc.

Use these as your benchmark. If a seller claims a much larger travel, faster jump speeds, higher electrode weight, or much heavier parts capacity without documentation, be skeptical.

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Inspection & Evaluation Checklist

Divide your inspection into mechanical / structural, electrical / power / control, EDM specific subsystems, and functional / test runs. Each area hides potential showstoppers.

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1. Documentation & Pre-Screening

Before arriving, request:

• Machine serial number, manufacturing year, machine build sheet, any retrofits or rebuilds
• As-built manuals, mechanical & electrical schematics, parts lists, wiring diagrams, maintenance logs
• Control / CNC (Hyper-i or predecessor) manuals, backup software, parameter sets, macros
• Past alignment / calibration / metrology reports
• Usage history: hours on power, hours in cutting/erosion, duty cycles, electrode materials used, shock events
• Photos/videos (or remote demo) of the machine in motion (ram, X, Y movement, tool change, dielectric flushing)
• Spare parts availability (power modules, transformers, servo drives, capacitors, dielectric pumps, electrode holders)
• Transport / logistic data: machine footprint, weight, lifting points, required clearance

If the seller cannot provide credible documentation or refuses motion or test videos, treat that as a strong warning.

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2. Structural & Mechanical / Motion Subsystems

These are among the hardest (and most expensive) to fix.

a) Frame, base & casting integrity

• Visually inspect for cracks, welds, repairs in the base, casting walls, head housing, columns
• Check for distortion in the casting—bending, sagging, or “twist” in major reference surfaces
• Verify that mounting surfaces, tank floor, and table support plane are flat and not warped

b) Ram (head) guides / linear ways / slide surfaces

• Move the ram (Z direction) slowly and feel for uneven friction, binding, stick/slip zones
• If possible, retract and extend the ram many times and observe consistency in motion
• Inspect guide surfaces (linear rails, guide bars, sliders) for scoring, pitting, corrosion, or wear flats
• Check that wipers, scrapers, dust shields or covers (if present) are intact—if they are missing or damaged, debris may have damaged the guides
• Inspect adjustment / preload systems (if the machine has adjustable guide preload, shims, or alignment screws)

c) X / Y axes (table motion) & reciprocal travel

• Jog the head in X / Y to ensure the full envelope is reachable with smooth motion
• Feel for any areas in X / Y where motion becomes stiff or changes friction — that may indicate localized wear or debris
• Check coupling / drives of X / Y axes (ballscrews, servo motors, guides) for looseness or play

d) Worktable, fixture mounts, and tank

• Inspect the worktable top: flatness, mounting holes, wear in fixture areas
• Check how rigidly the fixture mounts — any looseness or wear in the mount points can degrade accuracy
• Inspect the dielectric tank and its integration: tank walls, floor, seals, drains, structural support

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3. Electrical / Power / Control / Generator

This is often the “deal breaker” area for used EDM machines.

a) Power supply / generator systems

• Identify the EDM generator (power modules, capacitor banks, high-voltage circuits). Note their condition.
• Inspect high-voltage cables, connectors, insulation condition, porcelain bushings, dielectric feed-throughs.
• Check for signs of arcing, scorch marks, carbon tracking, or insulator breakdown
• Verify the cooling / chiller / transformer systems are functional and consistent (voltage stability, cooling fluid circulation)

b) Control / CNC / Hyper-i or predecessor control system

• Power-up slowly, monitoring for abnormal currents, blown fuses, or electrical smoke
• Examine wiring harness enclosures, terminal blocks, cable routing, cable insulation, repair splices
• Boot the control, navigate the UI, verify parameter sets, view alarms / error logs
• Jog X / Y / Z axes via control, check response, smoothness, reactivity
• Test synchronization (if any multi-axis moves)
• Verify limit switches, reference / home sensors, safety interlocks, E-stops
• Inspect position feedback sensors (linear encoders, resolvers if used) — ensure stable signal, no missed counts or noise

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4. EDM-Specific Subsystems & Fluid / Filtration / Electrode Handling

These are unique to EDM and often sources of hidden failures.

a) Dielectric fluid system, pumps, filtration & filtration lines

• Verify dielectric pump(s), pressure stability, plumbing integrity, valves, flow sensors
• Inspect filters, filter media, filter housings, clogging, bypass lines
• Check condition of dielectric fluid—may be contaminated with particles, sludge, or conductive debris
• Ensure all piping, flexible hoses, seals, flanges are intact with no leaks or brittle deterioration

b) Electrode handling / ATC system (if equipped)

• Cycle the ATC / electrode changer (if present) many times; check for mis-indexing, slowness, error during pick/place
• Inspect tool holders, holders for electrode seating, chucking force, alignment repeatability
• Check any electrode length measurement / touch-off systems for accuracy and consistency

c) Dielectric tank, rise/fall tank motion, tank integrity

• Some EDNC machines have a programmable rise/fall work tank design (moving tank up/down) — test that function: smoothness, speed, repeatability
• Inspect the tank walls, seals, floor, structural supports for corrosion, wear or leakage
• Check fluid level sensors, overflow protection, drains, and return plumbing

d) Z-axis jump / HS-Rib functionality (if applicable)

• If the machine has a high-speed jump Z-axis (HS-Rib) option, test its jump motion (non-cut) and compare to spec
• Check how well the system handles debris clearance during jump and its stability

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5. Functional / Cutting / Erosion Test & Acceptance Trials

This is the acid test. You must see actual EDM operation.

• Bring or request a test electrode, workpiece (conductive), dielectric, and run a typical pocket / cavity program
• Execute full-cut tests: roughing, finishing, dwell, electrode retraction, overcut, spark control
• Verify accuracy of electrode depth, spark behavior (stability, no arcs), pocket geometry, surface finish
• Perform return-to-zero, repeatability across axes, measure drift over repeated passes
• Run continuous cycles for several hours to test stability, cooling, drift, thermal effects
• Interrupt and resume, change electrode mid-program (if possible) and see consistency
• Test high-speed Z jump (if equipped) under real conditions
• Test full electrode tool-change / ATC operation under load

If the seller refuses EDM tests or only allows dry motions, that is a major red flag.

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6. Geometry, Calibration & Precision Evaluation

Even well-maintained EDMs can drift in geometry over time. You must verify the machine is still serviceable.

• Acquire or perform calibration / alignment data (laser, dial indicator sweeps, test blocks)
• Check:

  • Straightness in X, Y, Z axes
  • Squareness between axes
  • Repeatability (return-to-position) across full envelope
  • Electrode placement accuracy, drift with depth
  • Gap stability, spark centering accuracy

• Check whether the control supports compensation maps or geometric correction, and whether those maps are valid
• Estimate whether misalignment / drift is correctable (mechanically or by software compensation)

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7. Spare Parts, Serviceability & Long-Term Support

A used EDM is only as good as your ability to repair or maintain it.

• Confirm that critical spares are still available: power modules, capacitors, HV cables, dielectric pumps, chiller units, filters, motion drives, sensors
• Check whether Makino (or authorized service) supports EDNC in your region
• Identify local EDM service shops that can repair high-voltage components, power supplies, wiring
• Evaluate possibility of retrofitting newer control modules / drives if native ones become obsolete
• Ensure electrode tooling, holders, adapters, supplies remain available
• Try to acquire spare consumables (filters, spare pumps, filters, electrode holders) as part of the purchase

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8. Contractual Safeguards & Risk Mitigation

Even with a perfect inspection, hidden issues can emerge later. Protect yourself contractually.

• Insist on conditional / performance-based acceptance: final payment only after the machine passes your EDM test runs
• Define quantitative acceptance criteria: dimensional tolerance, surface finish, drift limits, spark stability, repeatability
• Negotiate a warranty / guarantee period (e.g. 30–90 days) covering major systems (power modules, control, motion)
• Require all documentation (electrical / mechanical schematics, backup software, calibration data, parts lists) to be delivered
• Clarify responsibilities for transport, rigging, leveling, installation, alignment, commissioning
• Insert “burn-in / commissioning period” clause: defects found under initial use must be remediated by seller
• Demand written disclosures of known damage, past repairs, power supply rework, or accidents

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9. Transport, Installation & Commissioning Considerations

Even excellent equipment can be damaged or misaligned in transit or poor setup.

• Confirm actual machine weight, footprint, required disassembly, and lifting points
• During move, use proper rigging, shock protection, structural bracing to avoid twist / stress
• After installation: re-level carefully, anchor or base-mount support without over-constraining
• Allow a robust commissioning / break-in period under real EDM loads
• After the machine settles, re-check geometry, drift, repeatability, spark stability
• Be present (or have your engineer) during first production jobs to monitor performance and catch issues early

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10. Red Flags & Deal-Breaker Conditions

If you see several of these, walk away or demand extremely favorable pricing + guarantees:

• Seller refuses full inspection, internal access, or real EDM test runs
• Visible repairs, burns, cracks, or modifications in frame, high-voltage lines, tank, casting
• Broken or missing dielectric tubing, insulator cracks, cable insulation damage, arcing signs
• Power modules / capacitors with burn marks, scorch, or signs of overheating
• Worn / damaged motion guides with scoring, pitting, or heavy wear
• ATC / electrode changer mis-indexing, slow, error-prone
• Flushing or filtration system in disrepair, leaks, clogging
• Control boards or power electronics obsolete or no longer serviceable
• Wiring harnesses with brittle insulation, many splices, patch repairs, signs of overheating
• Missing critical documentation (electrical schematics, control backup, calibration data)
• Spare parts for power modules, capacitor bank, drive electronics are no longer available or too expensive
• Geometry so degraded (drift, misalignment) that correction would cost more than replacement