Here’s a detailed inspection-to-installation checklist tailored for purchasing a used or surplus Doosan (formerly Doosan) DNM 750L (or equivalent large format machining center, made in South Korea) — especially useful given the heavy duty nature, size and complexity of such a machine. I’ll include what to verify before purchase, plus steps for installation. You provided a table of technical specs which I’ll reference when relevant.

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Pre-Purchase / Inspection Checklist

Before committing to buy, you’ll want to thoroughly inspect the machine, the documentation, the condition, and verify it meets your application and installation needs. Here are key points:

1. Verify machine identity & specifications

• Confirm exact model: “DNM 750L”, “DNM 750L II”, or other variant. Versions differ in travels, speeds, spindle, table load. For example, the DNM 750L Ⅱ has X travel ~ 2,160 mm, Y ~ 762 mm, Z ~ 650 mm.
• Compare the machine’s actual specs to your requirement:
  • Travelling distances: X, Y, Z axes
  • Table (length × width) and maximum table load
  • Rapid traverse speeds (in X/Y/Z)
  • Spindle: speed, taper (e.g., CAT/BT #40 or #50), motor power, torque
  • Weight of machine (so you know foundation/transport needs)
  • Control system (e.g., FANUC, Siemens, Doosan’s internal)
• Check the machine serial number, year of manufacture, hours or cycles operated, maintenance history.
• Make sure the machine you inspect matches the spec table your source lists. Your spec table shows:
  • Working travels: 600 / 770 / 810 mm in X/Y/Z axis
  • Max. speeds: 95 / 45 / 100 m/min in X/Y/Z axis
  • Interference diameter: 720 mm
  • Chip-to-chip time t1: 2.3 s (VDI 2852)
  • Positioning accuracy: 0.006 mm in X/Y/Z
  • Total machine weight: 15,000 kg without pallet changer / 17,500 kg with
  • Table load: 400 kg (A-axis) / 340 kg (B-axis) without/with pallet
    That table appears somewhat different from the typical spec sheets I found for non-lathe machines, so ensure you’re comparing “lathe” vs “machining center” correctly.
• Confirm that the machine’s documentation (manuals, schematics) is available and complete (especially for a used/surplus machine).

2. Structural & mechanical condition

• Check the machine’s bed, column, and base casting for cracks, repairs, deformation or welding repairs. Large machines often suffer from misuse or modification.
• Check guideways and ball screws for wear: look for pitting, scoring, excessive backlash, uneven surface finish, oil leaks, corrosion.
• Inspect spindle and tooling interface: check taper condition, cleanliness, presence of rust, wear or damage. Run the spindle (if possible) and listen for unusual noises, vibration.
• Inspect the machine table and fixture mounts: check flatness, straightness, surface finish, wear patterns, damage from previous operations.
• Inspect drives/feeds: servo motors, cable harnesses, limit/home switches, encoders. Make sure the drives operate smoothly, no jerky motion or overshoot.
• Check lubrication system: automatic lubrication pumps, oil levels, hydraulic circuits (if any), ensure they function and the filters are serviced.
• Check coolant system: coolant pump, tank, piping, chiller, cleanliness, any signs of contamination, corrosion. Cooling and thermal control is especially important on big machines. For example the DNM 750L Ⅱ spec mentions spindle head cooling system and ball screw nut cooling as standard.
• Check chip removal/conveyor system: large machines often produce large chip volumes; if the conveyor is damaged or missing, that is an extra cost.
• Check spindle drive belts (if belt drive), couplings, clutch, gears (if any) for wear.

3. Alignment, accuracy & performance testing

• Perform a geometric test: check squareness of axes, alignment of spindle axis relative to table, check if X/Y/Z travels correspond to specs, measure backlash in each axis.
• Check positioning accuracy: Your spec list shows “Positioning accuracy 0.006 mm in X-/Y-/Z-axis (mm)”. Confirm if the machine is capable of that, or what it is in actual condition.
• Run the machine empty (no load) and with typical load (if possible) and observe:
  • Spindle run-out (via test bar)
  • Measure repeatability (move to same point multiple times)
  • Measure thermal drift: let spindle run at speed, watch for expansion/shifts
• Check rapid traverse speeds: The spec says “Max. speeds 95/45/100 m/min in X/Y/Z”. Confirm the machine’s rapid traverse matches or nearly matches that. Rapid traverse may have been reduced due to wear or servo parameter changes.
• Check chip-to-chip time: Spec shows “Chip-to-chip time t1 2.3 s according to VDI 2852 (s) relative to speed (rpm)”. This is a productivity metric; ask for actual ATC times (tool change times) and if tooling magazine is functional.
• Check the interference diameter: Spec shows “Interference diameter 720 mm”. If applicable (for lathe or whatever model) verify if big parts can fit, t his is critical for your application.
• If the machine has a pallet changer (the spec table suggests “without/with pallet changer” weights), check the pallet changer mechanism: alignment, locking, repeatability, wear.

4. Electrical & control systems

• Verify control panel: Ensure display works, buttons/switches ok, emergency stop functional, axes homing works correctly.
• Check servo drives, spindle inverter, control cabinet: clean, no burn marks or smoke damage, no missing covers, maintenance logs.
• Check wiring and cables: look for wear, rodent damage, insulation cracks, missing ties.
• Check power requirements: large machines often need high-amp three-phase supply, special voltages. Ensure your facility in your country (or wherever you install) can provide the right supply (voltage, phase, frequency).
• Check safety features: guards, interlocks, chip guards, door safety sensors, correct functioning of E-stop circuits.
• Check compliance with local electrical safety regulations for used machines imported to your country (e.g., grounding, CE-marking, if required).
• Ask for software version, control updates, available software license, spare keys if applicable.

5. Documentation & history

• Request full service history: what maintenance has been done, how many hours or cycles run, any major repairs (spindle rebuild, guideway replacement, etc).
• Ask for original manuals, parts lists, wiring diagrams, control manual.
• Verify if any major modifications have been done (added pallet changer, 4th axis, extra automation). If so, check whether these modifications were professionally done and documented.
• Ask for machine inspection reports (if prior inspection done).
• Ensure machine is not subject to liens or outstanding financial obligations (important if purchasing from surplus or liquidation).
• Ask for original installation drawings/foundation requirements (helpful for your own planning).
• Request clear photos of machine condition (guideways, spindle taper, inside covers, recent repair sites) if you’re buying remotely.

6. Fit-for-purpose and compatibility

• Confirm the machine’s capacity meets your part size, weight, travel requirements, throughput. For example, if you need X-axis travel more than 600 mm, your spec table shows 600/770/810 mm; make sure whichever machine meets your actual part size.
• Check tooling and fixture compatibility: does the machine accept your desired tooling, workholding, spindle taper?
• Check available tooling magazine capacity and tool change time: if productivity is key, tool change time matters.
• Check availability of spare parts, consumables, especially in your country for a Korean-made machine: e.g., for spindle bearings, guideway components, control spares.
• Consider language/interface of control (if previously used in different country/language).
• Ensure machine centre will fit in your facility: dimensions and weight matter. The spec table lists weight 15,000 kg without pallet changer / 17,500 kg with pallet changer. Check your floor, lifting equipment, crane capacity, rigging, foundation.
• Consider transport/shipping: a 15 ton machine (or more) is not trivial.

7. Verify installation & logistic conditions

• Check the machine’s current location: is it anchored (bolted) to foundation? If yes, note how it was installed (grouting, anchor bolts).
• If it’s been idle for some time, check for corrosion, dust, rodent nests, missing covers.
• Inspect for oil leaks, hydraulic fluid stains, coolant residue, signs of neglected maintenance.
• Confirm all accessories, attachments, pallets/changers, tool magazines, control units, manuals are included.
• If machine is being moved from overseas (South Korea or another site), ensure proper packing, shipping logistics, customs, import duties for your country, and that you have a plan for rigging, anchoring, alignment upon arrival.

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Installation & Commissioning Checklist

Once purchased, and after transport to your site, there are important steps to ensure safe, accurate and efficient commissioning of the machine.

1. Floor/Foundation & Site Preparation

• Ensure floor can support the machine weight + dynamic loads. For ~15 000 kg machine, plus fixtures and workpieces, you might need a reinforced concrete pad or specialized foundation with anchor bolts and grout.
• Check levelness of the floor and prepare for machine leveling (shims, jacks, precision level, etc).
• Provide proper utilities: three-phase electrical supply (voltage/frequency matches machine requirement), chilled water (if spindle cooler or ball screw cooling exists), coolant supply, compressed air, adequate lighting, and ventilation.
• Ensure room size allows for machine footprint, maintenance access, chip removal and operator accessibility. For example, spec sheet shows overall dimensions for DNM 750L Ⅱ around 3480 × 4900 × 3170 mm (L×W×H) for certain variant.
• Provide adequate chip and coolant disposal and filtration systems (especially if the machine has large chip conveyor / chip auger).
• Ensure crane/hoist capacity for transport, lifting attachments, removal of major parts (spindle, headstock, etc) if needed.

2. Machine Set-Up & Leveling

• After positioning the machine, level it with precision tools (laser level, granite surface plate, etc) in all three axes.
• Bolt down anchor bolts, grout the base (if required) and allow proper cure time for grout before machine operation.
• Re-check level after grout cures and after initial operation (machines settle).
• Connect all utilities: electrical, coolant, compressed air, chiller, drainage.
• Fill lubrication reservoirs, coolant tanks, verify oil levels, priming of pumps, check filters.
• Turn ON machine with minimal load, check for abnormal noises, leaks, vibrations, electrical abnormalities.

3. Alignment & Calibration

• Once the machine is powered and stable, perform alignment checks:
  • Spindle to table perpendicularity and spindle run-out
  • Guideway straightness/levelness
  • Ball screw backlash
• Use a test bar or spindle test indicator to measure run-out and vibration.
• Run a test cutting operation (or simulated one) to verify repeatability, positioning accuracy, and to warm up the machine so any thermal drift is revealed.
• Adjust parameters if needed (servo tuning, backlash compensation, thermal compensation).
• Verify tool magazine/changer operation: tool pick-up/drop-off, indexing speed, safety interlocks.
• If there’s a pallet changer (or workpiece loader/unloader), verify its repeatability, alignment, locking mechanism, safety.

4. Safety & Operational Checks

• Ensure all guarding, interlocks, emergency stops are functioning correctly.
• Train operators and maintenance staff on safety procedures, machine controls, emergency shutdowns.
• Establish coolant and chip management procedures: safe removal of chips, coolant maintenance, disposal.
• Establish preventive maintenance plan: daily, weekly, monthly checks: lubrication, coolant, filters, clean guards, inspect belts/couplings, measure backlash/travel.
• Verify the control’s backups: program backup, parameter backup, look for any signs of tampering or missing data.

5. Production Readiness & Documentation

• Run accept-test parts with the machine under actual load to verify cycle time, accuracy and repeatability. Compare to your required production numbers.
• Document all baseline readings: alignment numbers, backlash, tool change times, spindle run-out, etc, so you have a reference for future maintenance.
• Store all manuals, wiring diagrams, schematic diagrams, parts lists in an accessible place (digital/physical) for maintenance use.
• Make sure you have a spare parts list and initial inventory of consumables (belts, filters, spindle bearing kits, guideway wipers) especially since used machines may need replacements sooner.
• Set up software version control and ensure you have the ability to update or maintain the CNC control software if required.

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Additional Considerations Specific to Second-hand Surplus Machines

Since you are looking at a used/surplus machine, more caution is needed:

• Verify whether the machine has been relocated before: moving large machines can cause misalignment, damage to guideways, etc. Ask for relocation history.
• Check for overdue major maintenance items: e.g., spindle rebuild, guideway regrinding, older control boards. If they’re upcoming costs, you should factor those into your purchase price.
• If the machine has been stored outdoors, in a damp environment or in poor conditions, internal components may be corroded or damaged.
• If the machine is being imported from another country, factor in transport cost, customs duties, import taxes, rigging at arrival, translation of manuals, local adaptation (e.g., voltage/frequency change) and potential adapter parts.
• Ensure that any warranty (if available) for used machine is specified and enforceable, or else treat it as as-is.
• Consider availability of aftermarket support for the model in Türkiye: are there local service engineers familiar with Doosan/ DN Solutions machines? Are spare parts readily available (spindle bearings, guideway wipers, control boards)?
• Check whether any modifications or non-standard accessories were added by prior users (such as custom fixtures, non-original ATC magazine, etc) – such items may cause future maintenance issues or part sourcing issues.
• Evaluate the expected remaining useful life: estimate wear on critical components (guideways, ballscrews, spindle bearings) and whether you should negotiate the price downward if major wear is evident.
• Ensure clear title of the machine: no outstanding liens, claims, or obsolescence issues (older control system may soon become unsupported).
• Make sure you have a contingency budget for teardown, alignment, balancing after installation. Large machines often need spindle balancing and mechanical alignment after transport.

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Summary Table of Key Items to Verify

Category	What to Check	Why It Matters
Model/Spec Compliance	Travel distances, table size/load, spindle specs	Ensures the machine will meet your requirements
Structural Condition	Bed/column cracks, guideways, spindle interface	Affects accuracy and reliability
Mechanical Systems	Ball screws, motors, lubrication, coolant	Worn components reduce performance & increase cost
Accuracy & Performance	Repeatability, backlash, spindle run-out, rapid traverse	Determines whether machine can hit required tolerances & productivity
Control/Electrical	Control system version, wiring, safety, drives	Affects usability, future support, and installation cost
History & Documentation	Service logs, modifications, manuals	Gives insight into machine health and future maintenance
Fit for Purpose	Tooling compatibility, fixture load, throughput	Already used machines must fit your production workflow
Installation Logistics	Weight, foundation requirements, utilities	Large machine means significant site prep and cost
Used/Surplus Factors	Prior relocation, wear, parts availability, warranty	These increase risk & may require extra investment