Here is a Technical Buyer’s Handbook / Due-Diligence Guide for assessing a DMG / DECKEL MAHO DMU 70 (5-axis vertical machining center) before purchasing a used or surplus unit. Use this as an inspection blueprint; adjust tolerances, weighting, and test depth to your precision / production requirements.

I also include benchmark specs and caveats drawn from real listings for DMU 70 / “eVolution” versions to guide expectations.

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0. Reference / Benchmark Specifications (DMU 70)

To know your target window, here are typical published specs for DMG/Deckel Maho DMU 70 / DMU 70 eVolution variants:

Parameter	Typical / Published Value
X travel	750 mm (≈ 29.5″)
Y travel	600 mm (≈ 23.6″)
Z travel	520 mm (≈ 20.5″)
Table / rotary table size	Ø 700 × 500 mm (circular table)
Max workpiece weight (on table)	~ 350 kg
Spindle speed	Up to 18,000 rpm in many units
Spindle motor / power	~ 22.5 kW (40% duty) / 15 kW continuous in some specs
Rapid feed (X/Y/Z)	~ 50 m/min
Linear axes feed	~ 20 m/min
B-axis swivel range	0 to 180°
C-axis rotation	360° with fine angular resolution (0.001°)
Machine weight / footprint	~ 8,320 kg, dimensions ~ 2,574 × 5,320 × 2,829 mm (for a 2001 eVolution unit)
Control / options commonly seen	Heidenhain TNC-426, iTNC 530, glass scales, internal coolant-through-spindle, automatic tool changer (ATC)

These figures are benchmarks; any candidate machine that deviates significantly should have a documented reason (e.g. retrofit, de-rated spindle, shortened travel) or be considered lower in value.

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I. Pre-Inspection / Remote Preparation

Before you commit inspection-time or travel, collect as much data/documentation and evidence as possible:

1. Request Documentation

• Factory mechanical, electrical, hydraulic, and control manuals
• Wiring diagrams, I/O maps, control schematics
• CNC parameter backups, tool offset tables, compensation maps
• Maintenance / service logs (spindle rebuilds, guide replacement, rotary axis overhauls)
• Calibration / alignment / geometry inspection certificates
• Retrofits or upgrades history (spindle changes, control upgrades, measurement systems)
• Spare parts list, tooling / fixture inventory
• As-is photographs / videos: machine exterior, table, axes, rotary table, tool changer, cabinet interiors

2. Ask Clarifying Questions

• Year of manufacture, serial number
• Total running hours / spindle hours
• Operating environment and materials machined heavily
• Reason for sale / decommission
• Known issues, collisions, repairs
• Option set: e.g. coolant-through-spindle (CTS), probe systems, thermal compensation, high-speed package, glass scales
• Control type / version, software backups
• Ask for video of axes motion, tool changes, rotary table spin

3. Prepare / bring Inspection Tools

• Dial indicators, test bars, feeler gauges, precision straight edges
• Laser interferometer / alignment tools (if available)
• Vibration sensor / accelerometer
• IR / thermography camera
• Tools to open control cabinets, measure wiring continuity
• Torque wrenches, micrometers

4. Logistics Check

• Machine weight, required lifting / crane capacity
• Foundation / floor load rating, leveling possibilities
• Power supply (voltage, phases, current capacity)
• Coolant / chip removal systems, filtration, piping
• Work area clearance, access for service, door widths

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II. Structural & Static Inspection (Power-Off)

Before powering, do a thorough structural and mechanical walk-around.

A. Frame, Base, Castings, Column

• Inspect base, frame, column castings for cracks, weld repairs, alignment repair marks
• Look for signs of foundation settling or shifting (shim stacks, uneven supports)
• Check for corrosion, pitting, chip / coolant damage in splash zones
• Inspect covers, way covers, bellows, seals for missing parts or damage
• Use a long straight edge or surface plate to check for twist or bending in structural members

B. Guideways, Linear Axes, Rotary / Swivel Axes

• Examine linear guideways, rails / slides for scuffs, pitting, spalling
• Check for side play or looseness in carriage blocks
• Inspect ball screws / drive screws and nuts for backlash, wear, binding
• Manually slide axes (if safe) to feel for friction, unevenness
• Inspect B / C axis (swivel / rotary table) bearings, gear teeth, disc edges for wear, backlash
• Inspect rotary table bearings/seals for damage or leakage

C. Spindle / Tool Interface

• Inspect spindle nose, taper, clamping surfaces for wear, chipping, burrs
• Check spindle housing, seals, cooling lines, lubricant leakage
• If possible, insert a test bar (non-driven) to measure static run-out
• Inspect coupling and bearing supports

D. Tool Changer / Tool Magazine

• Inspect tool magazine pockets, indexing mechanism, slides, grippers
• Check for worn or misaligned arms, slides, sensors
• Check magazine indexing, mechanical alignment
• Inspect actuator mechanisms and sensor wiring

E. Electrical Cabinets, Drives & Wiring

• Open control / drive cabinets (if permitted) and inspect wiring, terminal blocks, connectors
• Look for signs of heating damage: discolored insulation, burned parts
• Inspect drive modules, CNC boards, I/O boards for dust, damage, corrosion
• Check fans, filters, ventilation paths
• Inspect cable carriers / drag chains, moving cable wear

F. Safety, Interlocks & Limit / Home Switches

• Verify Emergency Stop (E-stop) buttons are present and mechanically functional
• Inspect guard doors, interlock switches
• Check limit / home / reference switches for each axis
• Ensure no bypass wiring circumventing safety circuits

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III. Power-Up & Functional / Dynamic Testing

After static checks, power on and run dynamic / functional tests carefully, ensuring safety protocols.

1. Control Startup & Diagnostics

• Power the CNC/control; watch boot logs, alarms, error codes
• Confirm that parameters, compensation tables, tool offset maps load cleanly
• Test I/O: ensure limit, home, safety interlocks, sensors report correctly
• Jog axes slowly; check direction, smoothness, no binding

2. Homing / Reference / Repeatability Moves

• Run homing or reference cycles on X, Y, Z, B, C axes
• Repeat homing sets to test consistency / repeatability of reference positions
• Trigger limit switches to confirm safe stops

3. Axis Motion & Traverse Tests

• Move each linear axis over full safe travel (within limits) to sense smoothness
• Command precise increments (e.g. 100 mm, 200 mm) and measure with dial indicator / metrology tool
• Reverse direction and measure backlash / dead zone
• Run composite / multi-axis simultaneous moves (e.g. X + B, Y + C) to check motion coordination

4. Rotary / Swivel Table / C-Axis Tests

• Spin the C-axis at various speeds; check for smooth, uniform rotation
• Test indexing / positional repeatability of C and B axes
• Load axis under torque, and test backlash / drift
• Verify locking / braking mechanisms under load

5. Spindle / Milling Operations Test

• Run spindle at incremental rpm to check vibration, noise, run-out
• If possible, mount test workpiece / tool and do light milling / facing
• Monitor spindle motor current, thermal behavior, stability
• Check cooling / lubrication effectiveness during runtime

6. Tool Change / ATC Tests

• Execute multiple tool change cycles; check timing, correctness, gripper performance
• Repeat multiple cycles to identify intermittent issues
• Use a range of tool lengths / sizes to test flexibility

7. Machining / Sample Operation

• Program a test operation (simple milling, contouring) with moderate parameters
• Measure resulting part geometry vs programmed path; assess surface finish
• Run repeated cycles to look for dimensional drift, thermal deformation
• Monitor vibration / anomalies during active machining

8. Safety / Fault / Interlock Tests

• Trigger E-stop during motion / milling / tool change; verify safe shutdown
• Trigger limit switches out of sequence to test error handling
• Open guard doors / panels during safe mode / motion (if allowed) to test interlocks
• Simulate sensor failures (if safe) and check error recovery behavior

9. Stability / Warm-Up / Drift Test

• Allow the machine to run idle or traverse continuously for 30–60 min to let thermal equilibrium settle
• After warm-up, re-test critical points, re-check backlash and accuracy to detect drift
• Monitor motor, drive, spindle, cabinet temperatures
• Use IR / thermography or vibration instrumentation to find hotspots or latent issues

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IV. Precision, Calibration & Accuracy Validation

Once the machine is thermally stable, perform precise measurement tests to evaluate its suitability.

• Repeatability test: move to a coordinate, retract, return, measure deviation
• Grid / mapping test: command mesh of points over X–Y–Z / B / C axes and measure deviations across entire envelope
• Squareness / orthogonality checks: move in one direction then another vs reverse order, check error difference
• Rotary / swivel axis angular accuracy: test C, B axes indexing and fine resolution accuracy
• Combined multi-axis machining test: e.g. simultaneous 5-axis movement, then measure resulting geometry
• Under load / extended overhang, test deflection / stiffness
• Use high-precision tools (laser interferometer, calibration spheres, precision probes) if available
• Compare results with the original spec tolerances and your required acceptance thresholds

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V. Documentation & History / Service Review

After mechanical and functional testing, thoroughly review all documentation and history.

• Maintenance & repair logs (spindle rebuilds, axis overhauls, table repairs)
• Calibration / alignment / geometry inspection certificates
• Retrofit / upgrade history (spindle changes, control upgrades, upgraded encoders)
• CNC / control software versions, backup parameter files
• Spare parts inventory (encoders, bearings, seals, tool changer components)
• Tooling / fixture inventory included

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

Using your inspection data, build a risk / cost model to decide what you’re willing to pay and how much refurbishment you must reserve.

• High-wear or high-risk subsystems: spindle bearings, rotary table bearings, B/C axis bearings, guide rails, ball screws
• Availability and cost of spare parts (especially for rotary / swivel axes, DMG / Deckel Maho OEM parts)
• Calibration / re-alignment / compensating cost after relocation
• Reconditioning of worn components (bearings, seals, rotary axis repair)
• Transport / installation risks (shock, misalignment during transit)
• Commissioning / downtime cost
• Obsolescence risk of control / electronics
• Salvage / fallback value of structural frame if machine fails

You may produce a weighted “condition score” matrix (structure, axes, rotary axes, spindle, tooling, control) to rank candidate machines and set a maximum acceptable bid.

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VII. Contractual Safeguards & Sale Agreement Clauses

Use your inspection leverage to negotiate protections in the contract.

• Acceptance / on-site test clause: final payment contingent on passing your functional and precision tests after installation
• Price adjustment / remediation clause: allow deduction / seller compensation if critical metrics deviate beyond agreed tolerances
• Warranty for latent defects: e.g. 3–6 months for hidden faults (especially in spindle / rotary axes)
• Spare parts and accessories requirement: require key wear components, tool holders, encoders, seals included
• Documentation handover clause: demand delivery of all manuals, wiring diagrams, CNC / parameter backups, past calibration data
• Transport / insurance clause: clearly assign responsibility for damage during shipping, handling, unloading
• Commissioning / setup support clause: require seller or OEM technical support during first alignment / calibration

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VIII. Post-Purchase / Installation & Commissioning Checklist

Once the machine arrives and is sited, follow a structured commissioning procedure:

1. Prepare or re-level foundation, anchor / grout base, check structural stability
2. Clean and flush lubrication / hydraulic / coolant systems, replace filters, check lines
3. Reconnect safety interlocks, guard doors, cable routing, grounding
4. Power up and run your full acceptance / dynamic / precision test suite
5. Perform full alignment and calibration (geometric, rotary axis zeroing, compensation mapping)
6. Run test parts (especially 5-axis work) in your materials to validate real-world performance
7. Capture baseline metrics: repeatability, backlash, drift vs time / temperature
8. Train operators & maintenance staff on specifics (rotary axis handling, 5-axis programming, safety)
9. Establish preventive maintenance schedule (rotary axis checks, spindle checks, geometric re-checks)
10. Monitor performance continuously in first weeks for deviation, drift, error trends