08/10/2025 By CNCBUL UK EDITOR Off

Technical Evaluation Guide: How to Identify a Quality Used, Secondhand, Pre-Owned, Surplus Okamoto ACC52 SA1 Surface & Profile Grinding Machine made in Japan

1) Machine Overview & Benchmark Specifications

Before arriving, request the original spec sheet or user manual so you have the manufacturer’s tolerances and capacities. For an Okamoto ACC52 SA1, typical specs may include:

Grinding wheel size: e.g. Ø 520 mm (or similar)
Spindle speed: e.g. 3,000 – 4,000 rpm (depending on wheel & motor)
Table travel (X / Y): approximate working surface travel
Max workpiece dimension / height clearance
Profile grinding capability (contour, cam, segments)
Motor / power ratings for main spindle and feed axes
Table / work support system and clamping mechanism
Control type: CNC or manual / semi-automatic
Dressing mechanism: rotary dresser, diamond dresser, etc.

These values let you judge how far off worn machines might drift.

2) Pre-Inspection Document Request

Request the following ahead of time:

Serial number, model designation, and year of manufacture
Original spec sheet / machine layout drawings
Maintenance & service logs (electrical, spindle, axes, dressing)
Calibration / accuracy certificates, geometry / flatness / straightness test records
Control / CNC parameter backups, axis compensation files
Wiring / electrical schematic diagrams
List of accessories (dressers, workholding, fixtures)
Records of past rebuilds, major parts replacement, crash history

These let you interpret what deviations are acceptable.

3) Visual & Static Inspection (Machine Off)

Conduct a methodical visual assessment before powering:

Machine base & casting: check for cracks, repairs, distortion, welded patches
Table / work surface / slides: inspect for pitting, wear, damage, irregularities
Lion’s share of bed / support structure: confirm stiffness, no sagging or visible bow
Wheel spindle housing / wheel mount: look for signs of impact, wear, taper damage
Wheel flanges / mounting faces: inspect for run-out damage, corrosion, wear
Guideways / cross-slide & feed rails: check for scoring, rust, lubrication residue
Dressing mechanism: inspect diamond dresser, rotation bearings, motor, slides
Electrical & control cabinet: open and inspect wiring, heat damage, component condition
Cabling, hoses, cables: inspect for brittle insulation, damage, cracking
Workholding / fixture mounts: check surface finish, mounting integrity
Coolant / lubrication plumbing: inspect hoses, fittings, leaks or corrosion

Take photos of any questionable wear or repair zones.

4) Installation & Alignment Checks

If the machine is mounted or partially installed:

Check machine base leveling and foundation stability
Mount a precision flat reference (e.g., granite block) on table and measure twist or deviations across the span
Mount indicators on the wheel spindle (without wheel) and check radial runout at various positions over table travel
Jog table (X/Y) in small increments and verify smooth, consistent motion
Command cross-slide motion (if profile grinding) and check consistency across profile axes

5) Power-Up & Functional / Motion Tests

After powering (with safety):

Warm-up jogging: move axes (table, cross-slide) continuously to stabilize temperature
Homing / reference return: verify repeatability and no reference errors
Axis traverse test: move X / Y / cross axes at varying speeds (slow to full feed) — listen / feel for binding, chatter
Wheel spindle ramp-up: accelerate spindle and monitor vibration, current, noise, smoothness
Dressing cycle: engage the dresser, perform a test dressing motion, verify smoothness, repeatability, no skipping
Test grind run (light cut): without heavy load, move wheel over table travel slowly — observe smoothness, engagement, wheel behavior
Coolant / lubrication systems: turn on coolant pump, confirm flow, check for leaks, delivery to zones
Control / alarm monitoring: review historical alarms, test limit errors / soft limits, sensor feedback
Cable / sensor feedback: observe signals during motion; no dropout or errors

6) Accuracy, Repeatability & Metrology Tests

Critical tests to gauge machine precision:

Use a precision flat test surface on the table and sweep the wheel across it; measure flatness error across table travel
Perform backlash / reversal error tests: command small ±0.01 mm feed in cross or Y and measure difference on reversal
Execute repeated positioning moves (e.g. 10×) to test repeatability of table / feed axes
If profile motion is present, run a contour test (arc or cam trace) and compare actual path vs intended geometry
After extended run (1 hour), re-measure key surfaces for thermal drift
Move axes to a position, dwell, return, and measure offset (hysteresis test)

7) Spindle, Wheel & Wear Checks

Mount a test ring or arbor and check radial runout of the wheel spindle
Run spindle at mid rpm and listen / monitor for bearing noise or vibration
Run the spindle for extended time and measure temperature rise
Inspect wheel mounting flanges, wheel balance (if available), wheel locking mechanism
If the machine has tool/chuck components on table, verify workholding alignment
Test wheel run through motion zones and check for deflection under feed

8) Lubrication, Cooling & Auxiliary Systems

Check that lubrication / grease / oil delivery to all slideways / axes is functional (no dry lines, leaks)
Run coolant pump; confirm correct coolant flow, pressure, check for leaks
Inspect filters, tanks, plumbing for contamination, rust, leaks
Operate chip removal or grinding swarf handling systems if present
Test cabinet cooling / ventilation; ensure drive / electronics do not overheat
Check hydraulic / pneumatic actuators, pressure stability, valves (if used for carriage control)

9) Wear Patterns & Red Flags

Table / surface wear or local dips (due to long travel)
Spindle taper wear or runout, damage
Cross-slide or profile axes wear, scoring
Dresser mechanism wear, stuck or inconsistent motion
Loss of lubrication or clogging, leading to increased friction or uneven movement
Coolant leakage or system failure
Electrical or control board failures, inconsistent signals
Cable chain fatigue or insulation breakdown
Inconsistent movement, jerk, or binding at extremes of travel

If multiple signs appear, it suggests the machine may require repair or reconditioning.

10) Acceptance Criteria & Tolerance Benchmarks

You can adopt the following as sample acceptable tolerances (then compare with spec sheet):

Parameter	Sample Target / Tolerance
Table flatness across travel	± 0.01 mm or better
Backlash / reversal error (cross / Y)	≤ 0.01 mm
Repeatability of axes	± 0.005 mm or better
Wheel spindle radial runout	≤ 0.005 mm
Thermal drift over 1 hour	≤ 5–10 µm
Dressing repeatability	± 0.01 mm or better
Coolant / lubrication stability	No major pressure / flow drop
Servo / axis current stability	Smooth traces, no spikes
Noise / vibration levels at rpm	Minimal, no bearing whine peaks

If the candidate fails multiple key benchmarks, proceed with caution or demand refurbishment.

Given the precision demands of surface / profile grinders, always demand a live grinding test (on a calibration flat or known test piece) and measurement of surface flatness / profile accuracy under full travel—no purchase should be finalized without it.