1) Machine Overview & Key Specs / Reference Data

First, gather the published / seller-provided specs so that you can measure deviations. These reference specs are based on current listings and MTI’s product line:

• The MTI 250B / BX is a rotary inertia friction welder model.
• A listing shows: 100 ton (force), 150 HP, max thrust 200,000 lb, max spindle speed 2,000 rpm, tailstock travel 25″, slide table to spindle centerline 19″.
• Another spec sheet lists the 250B / BX machine line in MTI’s inertia friction welder portfolio.
• Typical application in joining parts like valve bodies, piston rods.

From those, some “target values” you can expect (or demand) are:

Parameter	Reference / Typical Value
Force / capacity	~100 ton (≈ 200,000 lb thrust)
Motor / drive power	150 HP
Max spindle / rotational speed	~2,000 rpm
Spindle drawbar / clamping force	~15,000 lb (as per listing)
Tailstock travel	~25 in
Slide table to spindle centerline	~19 in

Use these as your bench marks; deviations should be explained by modifications or wear.

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2) Pre-Inspection Document Request

Before going to the site, ask the seller for:

• Serial number, build year, configuration (250BX or variant)
• Original spec / capacity sheet
• Maintenance logs (bearing changes, drive repairs, lubrication)
• Past weld trials / quality test reports
• Drawings / schematics (electrical, hydraulic, pneumatic)
• Control / programming manuals (Cyrq / CNC control)
• Any known damage, repair, or crash history
• Parts list (bearings, drive components, friction discs)
• Calibration / alignment / positioning verification reports

These documents help you define acceptable deviation thresholds.

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3) Visual & Static Inspection (Power Off)

With the machine de-energized:

• Frame, base & structure: inspect for cracks, weld repairs, deformations, sagging or misalignment over the long span
• Rotary spindle hub / turret / drive shaft: check for damage, dents, wear on bore or coupling surfaces
• Inertia flywheel / energy storage elements: if visible, inspect for cracks, welds, balance weights missing
• Bearing housings & supports: check for oil leaks, seal failure, wear marks
• Slide table / tailstock carriage: inspect for play, wear, alignment slop
• Tailstock or support spindle components: examine quill, slides, and supports for wear
• Drive motors, gearboxes, couplings: examine physical condition, broken teeth, misalignment, loose fasteners
• Control / CNC / operator cabinet: open panels, inspect wiring, burned insulation, loose components
• Cabling, power cables, coolant / lubrication lines: inspect insulation, connectors, signs of aging or chafing
• Hydraulic / pneumatic systems: inspect cylinders, hoses, seals for leaks or damage
• Mounting surfaces: check spindle bore, mating faces, surfaces for wear or burrs

Take detailed photographs of all suspicious areas.

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4) Installation & Alignment Checks

If machine is installed or partially mounted:

• Check that the foundation / base is stable, level, and properly anchored
• Mount a reference test bar or alignment bar to the spindle axis and check for radial runout at various radial positions
• Move the slide table / carriage along full travel and verify smoothness and consistency
• Check alignment of tailstock / support axis relative to spindle centerline using dial indicators
• Inspect coupling alignment and angular / radial alignment between motor, gearbox, and spindle

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5) Power-Up & Functional / Motion Tests

With safety procedures active:

• Warm-up motion: jog the table / carriage and drive axes for ~20–30 minutes to stabilize bearings, lubrication, temperature
• Homing / reference return (if control allows): perform repeated home cycles and check consistency
• Drive motion tests: command table movement (forward / reverse) at various speeds. Listen for binding, jerk, stuck spots
• Spindle ramp-up: gradually increase spindle speed up to maximum (e.g. 2,000 rpm), observing for vibration, noise, smooth acceleration
• Clamping / drawbar activation: test engagement and disengagement of drawbar / clamping for the rotating spindle
• Tailstock / support travel: move tailstock quill under power and manually, check for smoothness
• Hydraulic / pneumatic actuation: cycle any support or pressure systems (if used) to confirm responsiveness
• Control / alarm log review: inspect control’s error logs, test limit triggers, interlocks
• Encoder / feedback during motion: monitor for encoder or sensor fault during motion

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6) Welding / Load Test & Quality Checks

This is critical, because the machine must produce acceptable welds:

• Use a known standard test piece (matching typical application) and perform a weld under controlled parameters
• Inspect the weld joint: look for uniform flash, absence of voids, cracks, or discontinuities
• Perform destructive / tensile tests (if feasible) to check weld strength vs specification
• Across repeated welds, check consistency (repeatability) of weld geometry
• Under varying loads, verify the rotational speed control remains stable
• Monitor spindle torque, vibration, and backlash under loading conditions
• Assess tailstock / support alignment when under pressure during weld

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7) Bearing, Spindle, Couplings & Drive System Inspection

• Monitor bearing noise / vibration when spindle is rotating
• Measure spindle runout / wobble with test bar or precision tool
• Inspect couplings / torque arms for play, misalignment, wear
• Test the drawbar / clamping force to ensure it meets required retention load
• Examine gearboxes, belts, or drive trains for wear, backlash, looseness
• Under load, check for stable torque delivery and no dropouts

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8) Lubrication, Cooling & Auxiliary Systems

• Confirm lubrication / oil lines are functional, no blockages, leaks, or dry zones
• Activate any coolant or lubrication delivery systems, verify flow, pressure, absence of leaks
• Inspect filters, reservoirs, tanks for cleanliness, contamination, rust
• Cycle any hydraulic / pneumatic auxiliaries for smooth operation
• Check cooling / ventilation of drive cabinets and motor assemblies

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9) Common Wear & Failure Patterns / Red Flags

• Wear or play in spindle bearings or drawbar mechanism
• Excessive vibration or noise at lower or higher rpm
• Coupling misalignment or breakdown
• Drive system backlash or uneven motion at carriage
• Inconsistent weld quality, voids or non-uniform flash
• Lubrication failure or oil contamination
• Heat damage, control circuit degradation, solder joint failures
• Encoder faults, signal dropouts, sensor failures
• Cracked flywheel or imbalance of inertia mass

If several of these appear, the machine is high risk.

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10) Acceptance Criteria & Benchmark Tolerances (Sample)

You can use these as a “go / no-go” benchmark (adjust per the actual machine’s spec sheet):

Parameter	Target / Acceptable Tolerance
Spindle radial runout	≤ 0.005 in (or better, depending on spec)
Reversal / backlash in carriage	Minimal, e.g. ≤ 0.001 in over direction changes
Repeatability of positioning (table / carriage)	± 0.001 in or better
Weld quality consistency	Minimal variation over multiple cycles
Bearing noise / vibration	Smooth, no harsh whine
Drive motor smoothness / torque stability	No dips or surges under load
Lubrication / oil pressure stability	Consistent flow, no pressure drops
Temperature rise under load (spindle & bearings)	Acceptable rise after 30 min
Coupling / alignment error	Minimal, within spec
Clamping / drawbar retention force	Meets spec for safe retention

If you find the machine fails multiple key benchmarks (especially weld quality or spindle integrity), then any purchase should include major refurbishment or price adjustment.