Below is a Technical Buyer’s / Due-Diligence Handbook / Inspection Checklist for evaluating a pre-owned / used / surplus MAHO / MAT-500 (or “MAHO MAT 500”) CNC milling machine (bed- or column type, made in Germany). (“MAT” is a MAHO series prefix; many listings refer to “MH 500” variants, so adjust accordingly.) Use this as a detailed guide and adapt tolerances, priorities, and weightings to your shop’s needs (accuracy, size, spindle power, etc.).

I have also included reference data from publicly listed MH / MAHO 500 machines to act as benchmark targets you can compare against.

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0. Reference / Benchmark Specifications (for MAHO / MH / MAT 500 Series)

Before you go inspect, gather the exact spec sheet for the particular serial / configuration. Meanwhile, here are typical specs from used MH-500 machines which are in the same family and useful as benchmarks:

Parameter	Typical / Published Value
Travel (X × Y × Z)	500 mm × 380 mm × 350 mm
Table dimensions	800 mm × 355 mm
Spindle speed	Up to ~4,000 rpm, lower speeds around 63 rpm available
Tool holder / taper	ISO 40 (common in these machines)
Machine weight / footprint	Example: 3,200 kg, footprint ~ 2,100 × 1,800 × 1,900 mm (length × width × height) for MH 500 W variant
Power / drives / feeds	Rapid / feed speeds ~5,000 mm/min (for some units)
Control system seen	“Philips 432 / CNC 432” in some listings

These benchmarks are not exact for every MAT-500 but are good targets. When inspecting a candidate machine, deviations from these should be explained or compensated in your offer or refurbishment plan.

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I. Pre-Inspection / Remote Preparation

Before traveling, do as much preparatory work as possible:

1. Request full documentation
    - Manufacturer manuals: mechanical, electrical, pneumatic / lubrication
    - Wiring diagrams, control schematics, I/O maps
    - CNC parameter backups, axis tuning / compensation files
    - Maintenance / service logs (repaired axes, spindle rebuilds, linear guide replacements)
    - Calibration / alignment / inspection certificates
    - Modification / retrofit history (e.g. added probing, spindle upgrades)
    - Spare parts / BOM list
2. Request photos & videos
    Ask for clear, high-resolution images or video of:
    • The machine’s exterior (frame, column, base)
    • Table, guideways, linear axes, ball screws
    • Spindle head and nose, tool mount, spindle motor
    • Control cabinet interior (drives, wiring, connectors)
    • Motion demo (axis jogging, spindle rotation, tool change) if still powered
    • Underside, bed surfaces, coolant troughs
3. Ask key questions
    - Year, serial number
    - Total operating hours, duty cycle (heavy use vs light use)
    - Reason for sale or decommission
    - Any known faults, collisions, major repairs
    - What parts / tooling / fixtures are included
    - Is it currently functional / powered or has been disconnected
    - Control system version, software, backup state
4. Plan inspection tools & instruments
    Bring or plan to have:
    - Dial indicators, micrometers, test bars, straight edges
    - Laser alignment tools (if available)
    - Vibration / accelerometer sensor / portable vibration analyzer
    - Thermography / infrared camera
    - Feeler gauges, calibration blocks
    - Tools to open panels, inspect wiring
5. Logistics / site evaluation
    - Weights, rigging / crane access, lifting points
    - Foundation / floor load capacity, flatness
    - Power supply (voltage, phase, availability)
    - Coolant, lubrication, air, exhaust systems
    - Space clearance around machine for service & motion

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II. Visual & Structural Inspection (Cold / Power-Off)

Before powering anything, do a careful survey of all structural and mechanical components.

2.1 Frame, Base & Structure

• Inspect the machine’s base, column, and frame castings for cracks, weld repairs, distortions or signs of stress
• Examine leveling pads, base plate shim areas, anchor points for warpage or deterioration
• Check for corrosion, pitting, especially in coolant zones, chip areas
• Inspect covers, guards, way covers, bellows, seals for damage, missing parts, wear
• Check that machine appears level, not twisted (use straight edges)

2.2 Linear Axes, Guideways, Carriages, Ball Screws

• Inspect guide rails, sliding surfaces, ways for scuffs, scoring, wear marks, pitting
• Examine ball screws / lead screws for backlash, wear, damage
• Manually (if allowed) slide axes to check smoothness, binding, grit
• Check carriage play, side play or looseness
• Inspect lubrication lines, fittings, check for clogging or leaks

2.3 Spindle / Head / Tool Interface

• Examine the spindle nose, taper, threads, clamping surfaces for wear, damage, signs of misalignment
• Inspect spindle motor coupling / connection
• Check seals, cooling / lubrication supply to spindle, check for leaks
• If possible, mount a test bar (non-driven) and check static run-out
• Inspect the spindle housing for discoloration / overheating signs

2.4 Tool Change / Magazine (if applicable)

• Inspect tool changer arms, grippers, slides for backlash, wear
• Check sensors / proximity switches for alignment / damage
• Inspect magazine pockets, indexing mechanisms
• Check cables, wiring to tool changer mechanisms

2.5 Electrical / Control Cabinet & Wiring Infrastructure

• Open cabinets (if permitted) and inspect wiring terminals, connectors, insulation condition
• Look for discoloration, burned insulation, loose conductors
• Inspect drive modules, power modules, control boards for signs of overheating or damage
• Check cooling fans, filters, ventilation paths, dust buildup
• Inspect cable routing, strain relief, motion cable carriers for damage

2.6 Safety, Guards & Interlocks

• Verify existence and mechanical integrity of Emergency Stop (E-stop) buttons
• Inspect guards, door interlocks, safety covers
• Check limit / home switch presence and physical condition
• Confirm no safety systems appear bypassed or overridden

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III. Power-Up & Functional / Dynamic Testing

Once static inspection is acceptable and safety is assured, with caution power up and run dynamic tests.

3.1 Initial System Power-On & Diagnostic Checks

• Power up the control & CNC system; observe boot sequence, errors, warnings
• Confirm CNC parameters load correctly, no memory corruption
• Check I/O status: limit, home, safety inputs, sensor signals
• Jog axes at low speed: check direction correctness, smooth motion, no binding

3.2 Homing / Reference / Zeroing Cycles

• Execute homing or referencing for axes (X, Y, Z)
• Repeat multiple times to check consistency (back-to-back homing)
• Trigger limit switches intentionally to verify safe limit behaviors

3.3 Axis Travel & Accuracy Trials

• Move each axis through full safe travel at moderate speed, listening for jerk, stiction, binding
• Command known distances (e.g. 100 mm) and measure actual movement (via dial gauge / test device)
• Reverse direction, measure backlash or dead-band
• If available, run straight-line or circle motions to check cross-axis coupling or distortion

3.4 Spindle Running Behavior

• Run spindle at low rpm and gradually ramp up; monitor for vibration, noise, abnormal behavior
• If safe, mount a test workpiece or test bar, measure run-out under rotation
• Monitor spindle motor current, temperature behavior
• Check lubrication / cooling to spindle under running

3.5 Tool Change / Tool Handling Tests

• Execute multiple tool change cycles; observe motion smoothness, sensor feedback, accuracy
• Cycle tool changes repeatedly to test reliability
• Try changing tools of varying sizes (within safe limits)

3.6 Test Cut / Machining Simulation (if permitted)

• Run a light-cut test on soft material (e.g. aluminum) to simulate real usage
• Compare resulting part dimensions vs programmed path, inspect surface finish
• Let the machine run for a period to allow thermal effects, drift
• Monitor vibration, current draw, deviations over time

3.7 Safety / Fault Response Tests

• Activate E-stop during active motion or spindle run, verify safe shutdown
• Trigger limit switches or signal faults to check controlled stoppage
• Simulate sensor failures if safe, view error recovery behavior
• Open guards during motion to test interlocks function

3.8 Stability / Endurance / Drift Tests

• Run motion cycles or idle for 30–60 minutes to let thermal stabilization
• After warm-up, re-check key axes, backlash, repeatability
• Monitor motor / drive / controller temperatures
• Use thermography / vibration analysis to detect developing problems

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IV. Precision, Calibration & Accuracy Checking

Once the machine is stable (thermally and mechanically), test precision and calibration.

• Repeatability test: move to the same coordinate, retract, return, measure deviation
• Grid motion test: command a lattice of X–Y or X–Y–Z moves, measure deviations across workspace
• Squareness / orthogonality tests: e.g. move in X then Y vs Y then X, check differences
• Spindle overlay / alignment tests: if possible, test alignment between spindle axis and linear axes
• Under load / offset conditions (e.g. offset setup), observe deflection or deviation
• If you have high-precision tools (laser interferometer, calibration bars), use them for fine error mapping
• Compare measured errors vs acceptable tolerances (based on your application or machine’s original spec)

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V. Documentation & History Review

When you’re satisfied with mechanical / dynamic tests, review all historic and supporting documentation:

• Maintenance / repair logs (major work: guide replacement, spindle rebuilds, axis overhauls)
• Calibration / alignment certificates
• Retrofitting / modifications (CNC upgrades, spindle changes, added probing)
• CNC / control software version history, backup files
• Spare parts inventory included (lin. rails, ball screws, spindle parts, electronics)
• Tooling / fixtures / accessories provided

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VI. Risk Assessment, Life-Remaining Estimate & Cost Forecasting

From your inspection results, build a risk / cost model.

• Identify high-wear subsystems: spindle bearings, guide rails, ball screws, tool changer mechanisms
• Assess availability of spare parts (MAHO / German machine tool spares) and lead times
• Estimate cost for calibration / realignment / compensation tuning after relocation
• Consider transport / reinstallation risk (damage, alignment shifts)
• Estimate commissioning / downtime cost
• Consider control / electronics obsolescence risk
• Consider salvage / fallback value (structure, non-wear parts)

You may build a weighted scoring table (structure, axes, spindle, tool changing, control) to quantify condition and calibrate your maximum acceptable price or repair allowance.

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VII. Contractual Safeguards & Negotiation Clauses

Based on your findings, include protections in your purchase agreement:

• Acceptance / test clause: allow buyer to test machine after installation; condition sale on meeting agreed performance metrics
• Price adjustment clause: if measured performance deviates beyond agreed tolerances, seller agrees to reimburse remedy cost
• Warranty / latent defect clause: limited coverage period (e.g. 3–6 months) on hidden faults
• Spare parts package: require inclusion of critical wear parts (rails, screws, bearings, seals, electronics)
• Documentation handover clause: all manuals, wiring, backup parameter files, alignment / calibration records
• Transport / insurance clause: clearly allocate risk / liability during shipment
• Installation / commissioning support clause: seller or technical support assist during first commissioning and calibration

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VIII. Post-Purchase / Installation & Commissioning Checklist

Once the machine is relocated and installed, proceed methodically:

1. Prepare foundation, leveling, anchoring, vibration isolation
2. Clean and flush lubrication / coolant / hydraulic circuits; replace filters / fluids as needed
3. Re-mount and check guards, covers, safety interlocks
4. Power up and repeat your full acceptance / dynamic / precision tests
5. Perform alignment, geometry calibration, error compensation
6. Run test parts in actual materials to validate performance under your workload
7. Capture baseline data (repeatability, drift, backlash)
8. Train operators & maintenance staff
9. Establish preventive maintenance / inspection schedule
10. Monitor performance (drift, alarms, deviations) especially during the early weeks of production