- What remote inspection can and cannot tell you
- Step 1: Request the photo and screen pack
- Step 2: Set up the live session
- Step 3: Cold start and alarm history
- Step 4: Axes, way covers and backlash
- Step 5: Spindle warm-up and runout
- Step 6: Tool changer, turret and tailstock
- Step 7: Dry run and test cut
- Step 8: Controller, options and backups
- Step 9: Read the hour counters correctly
- Red flags and what they usually mean
- When to send someone on site
- What to put in writing afterwards
- FAQ
Most used CNC machines sold out of Korean factories are bought by importers who never see the machine before it is loaded. A remote inspection done in a fixed order replaces a factory visit for the questions that matter most: is this the machine on the quote, how hard has it worked, does it run without alarms, and is anything audibly or visibly worn. This guide is written for importers and dealers buying through an exporter in Korea, but the checklist works for any country.
What remote inspection can and cannot tell you
| Confirmed remotely | Not confirmed remotely |
|---|---|
| Model, serial number, year of manufacture (nameplate photo) | Positioning accuracy and repeatability of the axes (needs a laser test to ISO 230-2 on site) |
| Controller make, series, software version and installed options (system information screen) | Circularity, squareness and servo mismatch (needs a ballbar test to ISO 230-4 on site) |
| Hour counters: power-on, operating and cutting time (timer screen) | Spindle bearing preload and internal condition (vibration analysis or teardown) |
| Alarm history and current alarms | Hidden crash damage behind covers unless the seller removes them |
| Axis movement over full travel, audible noise, visible way-cover and ballscrew-cover condition | Fine surface finish quality under production conditions |
| Spindle run at several speeds, noise and warm-up behaviour, runout on a test bar shown on camera | Thermal growth over a full shift |
| Tool changer or turret completing a full cycle | Electrical cabinet wiring quality unless opened on camera |
| Backlash with a dial indicator shown on camera | Level and foundation condition at your site (irrelevant until installed) |
Step 1: Request the photo and screen pack before the call
Ask for the whole pack in one go and date it. Photos taken on different days from different machines are a common problem on listing sites, so insist on the serial number appearing in the first photo and the same machine background throughout.
| Photo or screen | What you read from it |
|---|---|
| Builder’s nameplate: model, serial number, year, voltage, weight | Identity and age; age limits in your country; electrical nameplate (Korean machines are normally 380V three-phase 60Hz) |
| Controller system information screen | Controller series, software version and option list; whether the display language can be switched to English |
| Timer or operation-time screen | Power-on time, operating time, cutting time and number of parts or tool changes where recorded |
| Alarm history screen (last 50 or more entries) | Repeated servo, spindle, overheat, lubrication or ATC alarms |
| Backlash and pitch-error compensation screens | Large compensation values or recent edits point to worn ballscrews |
| Spindle taper, close-up with light | Fretting, scoring or pick-up marks; a mirror or phone camera inside the taper works |
| Way covers and ballscrew covers, all axes | Dents, bent covers and chips packed behind them |
| Tool magazine, ATC arm or turret face, tool holders included | Bent pockets, damaged arm fingers, scored turret face |
| Chip conveyor, coolant tank, lubrication unit, hydraulic unit | Leaks, sludge, empty lube reservoir, low-level alarms |
| Electrical cabinet with the door open (with power off and a qualified person present) | Added wiring, burnt contactors, missing covers, moisture |
| Wide shot of the machine in its bay, from all four sides | Footprint, access for dismantling, whether it is still connected to power and air |
| Manuals, electrical drawings, parameter and ladder backups | What ships with the machine; missing documents are expensive later |
Step 2: Set up the live session
A live session fails when the machine turns out to be disconnected, when the operator who knows the control has gone home, or when the phone camera runs out of battery halfway. Agree the following before the call:
- Machine connected to power, air and coolant, and not in the middle of production.
- An operator who can drive the control is present, plus a person holding the camera. One person cannot do both.
- Camera on a tripod or held steady for indicator readings; a second phone for close-ups helps.
- Tools ready: a test bar for the spindle taper, a dial indicator with magnetic base, a clean tool holder, a piece of stock for a test cut, an infrared thermometer if available.
- Agenda shared in advance so the seller knows the session takes 45 to 60 minutes and the spindle must run long enough to warm up.
- Recording allowed. Ask for the session to be recorded and sent to you afterwards; it becomes part of the agreed condition.
Step 3: Cold start and alarm history
Ask for the machine to be switched off before the call and powered up on camera. A cold start shows battery-low warnings, absolute-encoder reference problems and any alarm that the seller has been clearing manually. Watch the screen from power-up to ready state, then open the alarm history and scroll through it slowly enough to read.
Note the date and time on the control. If the control clock is years out, the alarm history timestamps are meaningless. Ask the operator to home all axes and listen for the reference-return sequence.
Step 4: Axes, way covers and backlash
Have each axis jogged over its full travel in both directions at slow feed, then at rapid. Place the camera close to the way covers so that you can hear the axis. A healthy axis sounds even across the travel; a rumble that changes with position, a tick at the same point each pass, or a servo that hunts at a stop are worth a question.
Backlash can be shown on camera with a dial indicator: the indicator is mounted on the table or spindle head, the axis is moved toward the indicator in one direction to a reading, backed off by a small increment on the handwheel and returned, and the difference is read. Ask for the same check in both directions near each end of travel and in the middle. Then photograph the backlash compensation values on the control; a mechanical reading that is much larger than the compensation set on the control means the compensation has been adjusted recently or the screw is wearing unevenly.
On a lathe, run the carriage and cross slide the same way and include the tailstock quill. On a 5-axis machine, rotate the rotary axes slowly through their full range and listen for the worm or roller cam drive.
Step 5: Spindle warm-up and runout
Run the spindle at roughly 25%, 50% and 100% of maximum speed, two to three minutes at each stage, then leave it at a high speed for a further 15 minutes while the other checks continue. The camera should return to the spindle at the end. Points to record:
- Noise at each speed, with the camera close to the spindle nose and the room otherwise quiet.
- Temperature of the spindle nose after the warm-up, by infrared thermometer if available, otherwise by the operator’s hand with a comment on camera.
- Runout on a test bar mounted in the taper, read with the dial indicator at the collar and at the far end of the bar, shown on camera with the spindle turned slowly by hand.
- Spindle load meter at each speed with no cut; a load that rises steeply with speed suggests bearing drag.
- Orientation for the tool change: the spindle should orient to the same position every time without hunting.
Step 6: Tool changer, turret and tailstock
Ask for a full tool-change cycle through every pocket, not one tool change. On an arm-type changer, watch the arm pick up and insert tools at a steady pace without a pause or a knock; on a drum or umbrella type, watch the magazine index both ways. On a lathe, index the turret through at least two full revolutions in both directions and have the operator clamp a holder in a station with the indicator on it to show repeatability of the turret face. Include the tailstock and sub-spindle movements, chuck opening and closing, and bar feeder or parts catcher if included.
Step 7: Dry run and test cut
Have the operator run an existing production program in dry run or with the feed override low, with the camera on the screen and then on the machine. This shows the control executing a real program with the installed options and shows how the operator uses the machine.
If the seller allows, follow with a short test cut on the stock you asked for: a face and a shoulder on a milling machine, a turned diameter and a face on a lathe. Measure the result with a micrometer on camera and photograph the surface in good light. The test cut is not a precision test, but it confirms that the spindle, axes and control work together under load.
Step 8: Controller, options and backups
Return to the system information and option screens and read them slowly on camera. Confirm the controller series and software version against what you were quoted, note the installed options you need (for example rigid tapping, high-speed machining, tool life management, a probing cycle), and ask whether the control language can be switched to English.
Request a backup of the parameters, PMC or ladder, tool offsets, work offsets and macro variables to be made on camera and sent to you. A machine that ships without these backups can be difficult to bring back to life if a battery fails during transport. Check the battery alarm status for both the control and the absolute encoders before shipment.
Step 9: Read the hour counters correctly
Most controls keep several counters, and sellers often quote the smallest one. Ask for all of them to be photographed on the same screen.
| Counter | What it counts | How to read it |
|---|---|---|
| Power-on time | Time the control has been switched on | Compare with the machine’s age: around 2,000 hours per shift-year is a rough yardstick for a single-shift shop |
| Operating time (cycle time) | Time in automatic operation, programs running | The gap to power-on time shows idle time; a machine that mostly waited has light wear even if old |
| Cutting time | Time with the spindle and feed engaged in a cut | Cutting time close to operating time indicates heavy, continuous use; a large gap indicates setups and short cycles |
| Parts count or tool change count | Where recorded | High counts on an arm-type changer mean more wear on the arm and the magazine |
Counter values are stored as editable data on the control and can be reset or changed, so treat them as one piece of evidence beside the physical wear you saw on the way covers, the taper and the tool changer, and the alarm history. If the counters are unusually low for the machine’s age, ask when and why they were reset. Where the seller cannot answer, price the machine as one with unknown hours.
Red flags and what they usually mean
| What you see or hear | What it usually means | What to do |
|---|---|---|
| Seller refuses to power the machine up or to show a cold start | Alarms on start-up, or the machine has already been disconnected | Treat the machine as untested; price accordingly or walk away |
| Repeated servo overload or overheat alarms in history | Mechanical drag on an axis, failing drive or motor | Ask for the axis to be jogged while the servo load meter is on screen |
| Spindle growl at high speed or a nose too hot to touch after warm-up | Bearing wear; a rebuild is likely | Budget for a spindle rebuild or look for another machine |
| Runout on the test bar that grows along the bar | Taper wear, damaged taper or bent bar | Repeat with the bar rotated 180 degrees; if the error follows the spindle, the taper is worn |
| Backlash much larger than the compensation set on the control | Worn ballscrew or nut, loose coupling or thrust bearing | Check at three positions on the axis; uneven backlash points to the screw |
| Dented way covers, bent magazine pockets, a scored turret face | Past crash | Ask what was replaced after the crash and for the repair invoice |
| Control clock years out, counters implausibly low | Battery failure in the past, or counters reset | Treat hours as unknown; check the encoder battery status |
| Added wiring, bypassed interlocks, taped sensors in the cabinet | Workarounds for faults | Ask what each change was for; restore before shipment if possible |
| Different serial numbers between photos | Photos from more than one machine | Start the photo pack again with the serial number in each photo |
When to send someone on site
Remote inspection is enough for most general-purpose vertical machining centers and lathes at used-machine prices. Send your own engineer, or a third-party inspection service, when any of the following applies: the machine is a 5-axis or high-precision model where geometric accuracy is the reason you are buying it; the machine is expensive enough that a rebuild would change the decision; the remote session showed something you could not resolve; or your country’s import rules require a pre-shipment inspection certificate.
An on-site inspector can run a ballbar circular test to ISO 230-4, which shows backlash, servo mismatch, squareness and circularity of two axes in a few minutes, and a laser positioning test to ISO 230-2, which gives positioning accuracy and repeatability on each axis. The same ISO 230-2 figures are what export-control lists use to decide whether a machine tool is controlled, so for a high-precision machine the test result also feeds the Korean export classification. Agree in advance who pays for the test and what result lets you cancel without cost.
What to put in writing afterwards
A remote inspection only protects you if its result is written into the contract. Before you pay, the proforma invoice or sales contract should state the serial number, the counter readings seen on the screen with the date, the controller series and options, the condition seen at inspection including any defects you accepted, the list of accessories, tooling and documents that ship with the machine, the parameter and ladder backups to be supplied, and whether the machine is sold as seen or with any seller commitment. Attach the recording and the photo pack to the contract by reference. For a step-by-step view of the whole purchase, including the Korean export classification and shipping, see How to import a used CNC machining center from Korea.
Frequently asked questions
Can I trust the hour counters on a used CNC machine?
Only together with other evidence. Counters are editable data on the control and can be reset. Compare power-on, operating and cutting time with each other, with the machine’s age and with the physical wear you can see. Unusually low counters on an old machine should be treated as unknown hours.
What tools does the seller need for a remote inspection?
A test bar for the spindle taper, a dial indicator with a magnetic base, a clean tool holder, a piece of stock for a test cut and, if possible, an infrared thermometer. Most machine shops have all of these.
How long should the live video session take?
Plan 45 to 60 minutes. The spindle needs around 20 minutes to warm up for a meaningful noise and temperature check, and the other steps run while it warms.
Is a test cut enough to prove accuracy?
No. A test cut shows that the machine works under load and that the operator can run it. Positioning accuracy and repeatability need a laser test to ISO 230-2, and circularity and servo matching need a ballbar test to ISO 230-4, both done on site.
What if the machine has already been disconnected?
Then no running test is possible and the inspection is limited to photos, nameplates and a visual check. Either ask the seller to reconnect it for the session or price the machine as untested. An honest exporter tells you before the session whether the machine is still under power.
Related pages
- CNC machine tools from Korea: used and new
- Used machinery from Korea: brands, inspection and export
- How to import a used CNC machining center from Korea: 7 steps
- Korea 380V 60Hz machines: will they run in your country?
- How to verify a Korean exporter: 7 checks before you pay
- Korea export sourcing (hub)
HANA for U, a trading company near Incheon, sources machines against your request, runs the remote inspection described above with the seller, files the Korean export classification and ships with full export documents. Send the machine type, size, controller preference, year range and your country on WhatsApp.
WhatsApp +82-10-4568-0258
Prices, Incoterms and payment terms are stated on each quote. No stock list: every machine is sourced per request.
Sources
- ISO 230-2:2014, Test code for machine tools, Part 2: Determination of accuracy and repeatability of positioning of numerically controlled axes (checked 16 October 2026)
- ISO 230-4:2022, Test code for machine tools, Part 4: Circular tests for numerically controlled machine tools (checked 16 October 2026)
- Regulation (EU) 2021/821, Annex I, entry 2B001, machine tools (reference text; checked 16 October 2026)
Controller and machine brand names (FANUC, Siemens, Heidenhain, DN Solutions, Hyundai WIA, Hwacheon, SMEC and others) are trademarks of their respective owners and are used only to identify equipment. HANA for U is an independent exporter and is not affiliated with or authorised by any of them. This guide is general information, not engineering advice for a specific machine.
