If you’re looking to buy a used Hyundai WIA SKT-400LMC (or similar) CNC lathe / turning-mill center, you should check many things carefully. These machines are powerful and relatively complex; defects or missing parts can be very costly. Below is a checklist of what to pay attention to, plus tips & questions to ask the seller so you know what you’re getting.

---

Key Specs & What They Mean

Before you inspect:

• The SKT-400LMC is a large turning center with live tooling, C-axis indexing, tailstock, etc.
• Typical specs: ~ 2,000 rpm spindle speed, ~320 mm X-axis travel, ~2,200 mm Z-axis travel on one version; ~37/30 kW spindle power, etc.
• Big chuck (≈ 15″), decent bore for bar feed, full turret with multiple tools, possibly driven milling tools.
• It’s heavy and large; needs adequate foundations, power, cooling, etc.

Knowing the spec you require (part size, length, diameter, tool count, control type) helps you judge condition better.

---

What to Inspect / Evaluate

Here are the areas you should check in detail:

Area	What to Check	Why It’s Important / Potential Problems
Mechanical condition	• Bed, ways, slide surfaces: check for wear, grooving, pitting, rust. • Turret mechanism: indexing accuracy, backlash, wear. • Spindle: how does it run? Any unusual noise or vibration; spindle bearings condition. • Tailstock (if included): quill travel, alignment. • Joints, guide rails etc: condition, lubrication, play / backlash.	Wear or damage here affects dimensional accuracy, surface finish, and tool life. Repairs (e.g. replacing spindle bearings or regrinding ways) are expensive.
Live tooling / milling attachment	• Functioning correctly: check tool changes, driven tools (speed, torque, stability). • Alignment and accuracy when using live tools. • Condition of gearboxes or drive assemblies if used.	Live tooling issues reduce versatility; misalignment causes taper, bad surface finish. Gearboxes are expensive.
Control system / CNC & electronics	• Control brand/version (often Fanuc 21i-TB etc): is it well supported, do you know the version? • Check all axes move correctly; see if there are error codes. • Check the state of wiring, connectors, sensors, limit switches. • Do the drives / amplifiers / feedback encoders work reliably (no intermittent faults). • Function of safety interlocks, coolant, lubrication systems.	If electronics are old or poorly maintained, downtime or repair cost can be huge. Also controls may limit ability to run newer software or integrate tooling.
Accuracy / Test & Calibration	• Ask for a recent test / performance and accuracy report: straightness, concentricity, repeatability. • Check features like C-axis indexing accuracy. • If possible, run a test part (turning/milling) and measure it (tolerances, surface finish). • Measure spindle run-out. • Check backlash in axes.	Without verified accuracy, you don’t know if machine meets your needs.
Wear, Hours & Usage History	• How many operating hours the machine has. • What material types and what kinds of operations it has been used for (heavy roughing vs fine finishing). • Maintenance history: regular lubrication, coolant maintenance, tool changes, alignments. • Any history of crashes, overloads or misuse.	A machine used heavily for roughing will often have more wear. Misuse can shorten spindle / ways life severely.
Condition of tooling / attachments / accessories	• Is the chuck in good condition? Are jaws worn? • Any fixtures, steady rests, tailstock accessories included? • Is the chip conveyor working well; coolant system working; hydraulic/pneumatic systems leak-free. • Are tools / inserts etc included (or will you need to buy them).	These “extras” can add cost; missing ones might require you to buy separately. Faulty conveyors, coolant systems etc make production difficult.
Structural / foundation / alignment / environment	• Has the machine been moved? Was it realigned after move? • Floor vibration, leveling, anchoring: is the machine properly installed? • Environment: temperature control, cleanliness, dust, moisture. • Power supply: sufficient for motor loads, proper voltage, stable supply.	Even very good machines will perform poorly if misaligned, poorly anchored, or in adverse environments.
Wear on consumables	• Tool turret mechanism, indexing pins, slides. • Guide ways or box ways wear. • Spindle bearings, seals. • Hydraulic seals, coolant pumps, filters.	These wear parts often have significant cost; replacement might be difficult or expensive.
Spare Parts & Support	• Are parts for this model still available? • Is there local support/technicians familiar with Hyundai WIA / Fanuc etc? • Is documentation/manuals included? • Is software/configuration backed up and transferable?	If parts or support are hard to get, downtime or repair cost rises. Missing manuals/documentation make set-up, troubleshooting harder.
Power / Utilities / Running Costs	• Energy consumption; what motor amps are used. • Coolant and lubricant consumption; whether cooling/chiller system is functioning. • Air supply and filtration if needed. • Maintenance cost: how often needs servicing; cost of spindle replacement etc.	Operating cost is often more over the lifetime than purchase cost. You want one with good efficiency and lower upkeep.

---

Questions To Ask The Seller

To fill the gaps, here are useful questions:

1. How many hours has the machine run, and under what kind of usage (material, roughing/finishing)?
2. What maintenance has been done – regular lubrication, spindle rebuilds, alignment, calibration?
3. Has it ever had spindle bearing issues, crashes, or damage to ways/turret?
4. What is the condition of the live tooling / milling tools and C-axis – are C-axis drives healthy; is gear/drive backlash minimal?
5. What control version is installed; is it fully functional; any error history?
6. Are all accessories included (chuck, jaws, tailstock, steady rest, fixtures, coolant, conveyors)? Are spares available or provided?
7. Do you have recent calibration / test report or can you run a test part?
8. What is the condition of coolant, lubrication, hydraulic systems; any leaks; replacement history?
9. What is required to move, install, re-level the machine; what power supply is needed; will you supply wiring or modifications?
10. Are manuals, schematics, parts lists included? What about software backups or configuration files?

---

What Might Be Painful / Hidden Costs

Be aware of potential traps:

• Spindle rebuilds are very expensive, especially if bearing condition is bad.
• Wear on ways / turrets might only become evident under load or after long usage.
• Outdated or poorly supported control systems or electronics; replacement of drives can be costly.
• Setup and alignment after transport can be nontrivial. If misaligned, accuracy suffers.
• Live tooling gearboxes deterioration; tool holders or driven tools needing replacement.
• Hidden deterioration of hydraulics, coolant systems, seals etc can lead to downtime.
• If you require high precision, may need re-certification/calibration, which adds cost.

---

How to Decide If It’s a Good Deal

After inspection and questions you can judge by:

• Compare the machine’s tested accuracy vs what your parts require. Don’t overpay for precision you don’t need.
• Estimate all additional costs (transport, installation, calibration, any replacements) and factor into the purchase.
• Compare cost of used vs cost of new (or factory-refurbished) to see what discount you’re getting.
• Think about downtime risk and spare parts availability locally. A little more upfront cost for a better condition machine may save much more later.
• Consider resale value: models with good control systems, documented history and good condition command better resale.