Here’s a detailed, structured guide (with Mori Seiki SH-630–specific notes) for evaluating a pre-owned / secondhand / surplus horizontal machining center before purchase. Use this as your on-site and off-site “due diligence” checklist.

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1. Know the Machine — Baseline Specs & What to Verify

Before going on site, get the machine’s spec sheet, original manual, and any as-built or modification records. Use those numbers as your reference. Here are typical published specs & variants for the Mori Seiki SH-630:

Spec	Typical / Catalog Value*	Notes / Variation Possibilities
X travel	~ 33.1 in (≈ 840 mm)	Some units might be re-built or re-stroking; verify physical travel with dial indicator.
Y travel	~ 29.9 in (≈ 760 mm)
Z travel	~ 33.1 in (≈ 840 mm)	This is from table to spindle or table travel depending on variant.
Spindle speed (max)	10,000 rpm	Verify whether original or upgraded; also need to check condition at high rpm.
Spindle taper / tool holding	CAT-50 (or BT/ISO 50 variant)	Confirm exact taper and toolholder interface; check if the spindle nose is modified.
Spindle motor power	~ 40 hp (≈ 29.8 kW)	Some listings show 30 HP or 40 HP depending on variant.
Tool changer / ATC	60-station typical in many ads	Some units may have 120+ or dual magazines.
Pallet size & system	~ 24.8″ × 24.8″ (≈ 630 × 630 mm) pallets, 2 pallets typical	Some units may have more pallets or rotary indexing pallets.
Control & electronics	Often MSC-516 or MSC-502 (Mori Seiki’s controls)	Confirm the control version, firmware, spare parts availability.
Machine weight & footprint	Large / heavy — substantial foundation & crane needs	Be prepared for high rigging and transportation costs.

* Always confirm the as-sold unit’s specs; modifications and retrofits are common in used machines.

Knowing these baselines helps you immediately spot deviations or red flags (e.g. a model claimed to be “SH-630” but with only 6,000 rpm spindle, or missing ATC, or very short travels).

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2. Preliminary Paperwork & Questions (Before Visiting)

Ask for the following ahead of your visit — the answers (or absence thereof) will guide how deep you dig on site:

• Service / maintenance logs — especially spindle rebuilds, bearing replacements, ATC repairs, major collisions or overtravel events
• Operating / cutting hours on spindle / axes
• History of crashes, collisions, or repairs (e.g. spindle crashes, table strikes)
• Retrofits or upgrades — e.g. spindle upgrade, ATC change, electronics upgrade, pallet system changes
• Parts availability & sources for Mori Seiki / MSC controls, spindle bearings, etc. in your region
• Accessories included — pallets, fixtures, chucks, workholding, tool holders, software licences, manuals, wiring diagrams
• Transport & rigging plan — how the seller plans to move it, disassemble/reassemble, alignment included?
• Warranty / return or test period — even used sellers sometimes provide limited guarantees or test-cut periods

If the seller cannot provide credible logs or is vague, consider that a risk.

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3. Visual & Structural Inspection (Before Powering On)

Walk the machine thoroughly. Many serious defects can be caught or inferred without powering it. Here’s what to look for:

A. Structure, Castings & Enclosures

• Check for cracks, weld repairs, or distortions on the base, column, saddle, and bed.
• Inspect the guideway covers, wayguards, bellows — tears, missing sections, or damage probably allowed chip/coolant ingress, which wears down surfaces.
• Examine for corrosion, rust, pitting especially in coolant zones, base, bed surfaces, column edges.
• Look at panels, doors, guards, limit switch covers — are they original, missing, patchwork repairs?
• Inspect the wiring harnesses, conduit, cable carriers for chafing, splices, nonstandard patches, etc.
• Evaluate the ATC / magazine assembly for bent parts, missing fingers, alignment marks, or signs of collision.
• Check coolant sump, pumps, piping, filtration, chip conveyor — heavy sludge or rust may point to neglected maintenance.

B. Static / Mechanical Checks (Manual Probing)

• Try to manually jog or move axes (if safe) or carefully use hand jog to feel for binding, stiff spots, or jerkiness.
• Check for backlash / play in each axis: push in one direction, reverse, measure how much “dead” movement before motion.
• Mount a test bar or known tool in spindle and gently check for axial / radial play (wiggle).
• Examine the ATC magazine indexing / turret (if a rotary or linear magazine) for smooth motion, missing parts, or damage.
• Check for lubrication feed lines, oil ports, fittings — clogged, missing, or corroded lines indicate neglect.
• Check table surfaces, pallet faces, and pallet locating surfaces: are they flat, undamaged, or worn?

If you see serious structural repairs, cracked castings, or heavy damage, that’s a major red flag.

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4. Power-Up & Basic Electrical / Control Checks

With power applied (safely, following electrical protocols), start basic control and drive checks.

• Observe the boot sequence of the control: any alarms, errors, missing modules, or unusual messages?
• Test control panel buttons, switches, jog keys, display responsiveness.
• Engage drives in manual jog or “remote mode,” moving each axis slowly: see whether drives fault, alarms occur, or movement is erratic.
• Test safety circuits: E-stop, door interlocks, limit switches.
• Monitor power draw, voltage stability, any surges — though full loads may not be tested yet.

If the machine refuses to boot cleanly or the drives show repeated faults, you have a serious problem.

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5. Dynamic Motion & Accuracy Tests

Assuming control and axes respond, run through a structured motion and accuracy test:

A. Axis Motion & Repeatability

• Jog each axis through full travel (slow → medium → faster speeds). Listen for abnormal noises (grinding, whine, squeal).
• Reverse directions and measure backlash / reversal error for each axis using a dial indicator or test instrument.
• Move, stop, reverse: measure how precisely the machine returns to a commanded point (repeatability).
• Command combined-axis moves (e.g. circle interpolation) to test smoothness and consistency.
• If available, run a ballbar test (or circularity test) — it’s a powerful tool to detect geometric and servo errors.

B. Spindle Performance

• Run spindle at several speeds (low, mid, high). Listen for bearing noise, hum, vibration.
• Use a dial indicator to measure radial runout (on the spindle nose or a held tool).
• Let it run for a short period to see if temperature, vibration, or noise changes (heating issues might emerge).
• If possible, run a light cut in soft material and monitor how the spindle behaves under load.

C. Test Cuts & Realistic Machining

• Always insist on a test cut / sample part: turning, facing, boring, side milling, etc.
• Check dimensional accuracy, surface finish, consistency across locations on the part or table.
• Try cuts pushing toward limits (long traverse, heavy cuts) to see if deflection, chatter, or vibration manifests.
• Monitor coolant flow, chip evacuation, chip accumulation, coolant leakage issues.

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6. Geometric, Alignment & Metrology Assessment

If you have access to inspection tools (or bring a metrology technician), these checks are critical for understanding how far the machine is from ideal alignment.

• Check straightness / flatness of axes over travel using gauge blocks, straight edges, or laser interferometry.
• Evaluate parallelism of axes (e.g. spindle axis relative to axes, axis-to-axis parallelism).
• Assess squareness: e.g. whether Y-axis or X-axis is square to spindle axis across travel.
• Measure positional accuracy / linearity: command various distances and measure actual distances across full strokes — check for scale errors.
• After warm-up, monitor thermal drift over time in X, Y, Z.
• At extremes of travel (e.g. full extension of Z, or far end of X), test for sag, deflection, or geometric distortion.

Be aware: some geometric errors can be corrected (shimming, alignment, software compensation), but structural or severely worn ways often are expensive or impossible to fully restore.

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7. Estimate Refurbishment & Undisclosed Costs

Even a well-maintained used machine will likely need some work. Budget accordingly. Possible refurbishment or deferred maintenance items include:

• Spindle rebuild / bearing replacement
• Replacing or refurbishing ATC magazine, indexing gear, fingers, cams
• Ball screw nut replacement or regrinding
• Re-scraping / re-lapping / way grinding / surface restoration
• Servo drives, feedback systems, wiring harness repairs
• Replacement of sensors, limit switches, proximity switches
• Coolant system overhaul (pump, piping, filters, seals)
• Re-leveling, alignment, shim work, calibration
• Electrical / control modernization if needed
• Spare parts (bearings, seals, servo modules, tools)
• Transportation, rigging, disassembly, reassembly, alignment and commissioning
• Software backup / control licensing / maintenance contracts

Also include cost of downtime and risk of hidden damage discovered post-installation.

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8. Red Flags & Deal-Breakers

Some conditions should either push you to demand a big discount or walk away altogether:

• Spindle with audible noise, high vibration, or overheating issues
• Control that refuses to boot cleanly, drive modules that fault, or missing control modules
• Excessive backlash or play that seems beyond repair
• Major structural defects (cracks, welded repairs) on bed, column, base
• Catastrophic ATC / magazine damage (bent arms, missing fingers)
• Inability to perform any sample cuts or test under load
• No documentation, wiring diagrams, or spare parts available
• Obsolete electronics with no end-of-life support or hard-to-source replacements
• Seller unwilling to permit inspection, trials, or limited acceptance window

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9. Strategy for Making an Offer & Negotiation Tips

• Start with a conditional “subject to inspection / trial / acceptance” offer, rather than blind full price.
• Itemize faults or deviations you discover, and deduct appropriately.
• Ask seller to include spare parts or a refurbishment allowance for known issues.
• Negotiate a limited warranty or acceptance period after installation and test-cuts.
• Factor in your total “installed cost”, not just purchase price (transport, rigging, alignment, reman costs).
• Walk away when the total cost to bring to reliable production condition exceeds a new, refurbished, or better-used alternative.