When evaluating a pre-owned Cincinnati Milacron E90 blow molding machine (or similar accumulator-head blow molder) you need to dig deeply into both its mechanical / hydraulic systems and the process-critical wear areas. Below is a tailored, step-by-step “Industrial Insights” guide you can use as a checklist or decision tool to spot quality (or red flags) before purchase.

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What to Know about the Cincinnati Milacron E90 as a Baseline

Before inspection, having the “as-designed / catalog specs” helps you catch exaggerations or hidden degradation. From listings and used machine sales, here are representative specs and features for the E90 (or variants) to use as a reference:

• Many E90 units are described as accumulator head blow molders (i.e. accumulator head system).
• A common configuration is single 5 lb shot size, with a 90 mm extruder (i.e. screw diameter ~ 90 mm).
• Typical clamp / platen dimensions: e.g. 40″ horizontal × 30″ vertical clearance in some units.
• Clamp force (depending on variant) in many listings is ~ 50 tons.
• Many E90 machines use CAMAC / Camac PLC control or CAMAC 486 sequencing controllers.
• In a listing of a 1993 E90: “Shot size 10 lbs, platen size 48″ × 40″, hyd. drive output 60 HP, approx output 660 lbs/hr (70% virgin / 30% regrind)”
• The E90 is offered in dual-head versions, accumulator head(s), with substantial hydraulic and clamp systems.

Use these as rough “expected ranges” for comparisons when the seller presents their unit.

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What to Inspect & Test — Detailed Checklist

Here’s the detailed checklist (mechanical, hydraulic, control, operational) you should carry with you or demand from the seller. As always, wherever possible see it running (no-load and with material) before committing.

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A. Documentation, History & Setup

1. Machine identity / nameplate / serial number / build year
   • Confirm model (E90) vs what seller claims.
   • Write down serial number, and if possible check original build documentation or OEM literature for what the machine should have (clamp force, hydraulic system, control options).
2. Service history, maintenance logs, repairs
   • Ask for logs of preventive maintenance, overhauls, part replacements (e.g. hydraulic cylinders, seals, accumulator components).
   • If the machine has had major breakdowns or neglected maintenance, that is a risk.
3. Original drawings, hydraulics schematics, control / PLC / wiring diagrams
   • These help for troubleshooting, part replacement, and verifying modifications.
   • Insist on getting them transferred with the sale.
4. Included tooling, molds, spare parts, accessories
   • Are molds, dies, heaters, accumulators, valve banks, spare seals included? What condition are they in?
   • If the seller has spares (seals, cylinders, controllers) that’s a positive sign.
5. Modifications / retrofits / upgrades
   • Has the machine been retrofitted (e.g. new control, updated hydraulics, added safety features)?
   • Ensure modifications are documented; check whether they were done properly (alignment, calibration, testing) and whether they introduce any compromises.

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B. Mechanical / Structural / Hydraulic Condition

6. Frame, platen, tie bars, clamp structure
   • Inspect for any cracks, weld repairs, distortions, corrosion, or misalignments in the clamp structure or platen surfaces.
   • Use straight edges, precision measurement tools to check platen flatness, parallelism, and alignment.
7. Clamp / platen surfaces, bearings, alignment
   • The platen surfaces should be flat and free of scored or gouged surfaces.
   • Verify parallelism and squareness of moving platen and fixed platen.
   • Measure runout or tilt across platen faces.
8. Tie bars / guiding rods
   • Inspect tie rods or guide bars for wear, bending, surface damage or scoring.
   • Check bushings or bearing systems on platen slide mechanisms for play or misalignment.
9. Hydraulic cylinders, pistons, seals
   • Examine piston rods, cylinder barrels, seals for signs of scoring, pitting, corrosion, leaks.
   • Operate the platen (extend / retract) slowly and check for stiction, jerky motion, or asymmetry (i.e. one side dragging).
   • Look for external leaks, weeping at seals or port connections.
10. Accumulator / accumulator head system
    • In an accumulator-head machine, inspect the accumulator, check pressure holding, check seals, valves, and whether the accumulator can maintain correct pressure under static conditions.
    • Confirm accumulator head (if two heads) are equal in condition, synchronized, and free of leakage or imbalance.
11. Extruder / screw / barrel & melt system
    • Since the E90 combines extrusion + blow molding, inspect the screw & barrel: check for wear, pitting, scoring, clearance to barrel walls.
    • Test the extruder drive, heater bands, thermocouples, melt zone temperature stability.
12. Clamping hydraulics, pressure systems, valve blocks, pumps
    • Inspect pump(s), hydraulic supply, manifolds, valve banks, pressure relief / control valves, plumbing and hoses for wear, leaks, fatigue.
    • Check the hydraulic fluid condition: clarity, absence of metal particles, correct viscosity, no contamination.
    • Measure pressure stability under load; fluctuations or instability are red flags.
13. Cooling, temperature control, piping, heat exchangers
    • Check cooling circuits, lines, heat exchangers, water jackets, possible blockages or corrosion.
    • Ensure there is adequate cooling for extruder, mold, head, and that temperature control is stable.
14. Movement systems, linear guides, slide rails
    • If there are auxiliary axes (e.g. mold movement, hydraulic indexing, platens shifting), inspect guides, rails, alignment, lubrication, play or slop.
15. Frame supports, machine mounting, leveling
    • The machine must have been well‐leveled in its prior location. Check for signs of floor stress, uneven mounting, base warpage, anchor bolt damage.
16. Safety systems, guards, interlocks, emergency stops
    • Inspect whether guard doors, interlocks, safety covers, E-stops are in place and functional.
    • For older machines, check whether they can be upgraded to meet your local safety standards.

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C. Control & Electrical / Automation

17. Controller / PLC / HMI
    • Inspect the controller (e.g. Camac PLCs used in many E90 units) for condition, reliability, spare parts availability.
    • Ask whether backups / original software / programs are included; whether there have been control upgrades or replacements.
18. Sensors, wiring, cables, connectors
    • Inspect all sensors (pressure, temperature, flow, position), wiring harnesses, connectors for damage, wear, loose or brittle insulation.
    • Look for evidence of overheating, arcing, or amateur rewiring.
19. Motors, drives, variable frequency drives (VFDs)
    • Test motors (extruder motor, servo motors, platen motors) — spin them, check bearings, insulation, noise, heating.
    • If VFDs or drives are used, check their health, control interfaces, spares availability.
20. Interface / automation / user programming / parison control
    • For complex blow molding, parison programming, synchronization between extruder / accumulator / mold / blow lines is vital. Test these functions.
    • Examine historical programs, control logic, ability to modify, diagnostics.

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D. Operational / Performance Tests

21. No-load / dry-run test
    • Run the machine (without material) through all axes: platen open/close, accumulator head motion, extruder rotation (with barrel heaters off if safe), hydraulic cycles, turret or mold indexing if present.
    • Listen/feel for smooth motion, absence of jerks, no unexpected vibration or stick–slip in hydraulic movement.
22. Clamp / platen stroke, speed, pressure behavior
    • Command full stroke / full cycle and measure time, compare with spec or what seller claims.
    • Monitor pressure profiles, stability, response to commands, consistency over cycles.
23. Accumulator head / shot transfer tests
    • If possible, test accumulator charge / discharge cycle, shot transfer, synchronization of accumulator head(s) with extruder output.
    • Ensure there is no lag, misfire, or shot‐to‐shot variation.
24. Extrusion test under load
    • Run some material (if seller permits) through the extruder / accumulator / head to confirm that the melt quality is acceptable, that flow is stable, and that temperature / melt control is smooth.
    • Monitor melt pressure, temperature stability, flow consistency, fluctuations or surging.
25. Mold / blow / necking / blow cycle test
    • If the blow molding function (mold close, blow, part ejection) can be run, test it. Use a mold or dummy piece if available. Measure cycle time, check for proper blow pressure, consistency, part quality.
    • Inspect produced parts (if test run) for variation, defects, thickness consistency, structural integrity.
26. Thermal stability / drift test
    • Run the machine for a prolonged period (several cycles under load), then re-measure key dimensions (platen alignment, pin distances, shot volume consistency) to see whether heating causes drift or misalignment.
27. Leak / sealing test under full pressure
    • While under operating pressures (hydraulic, accumulator pressure, melt pressure), inspect all seals, joints, pistons, fittings for leaks (even slow weeping).
    • Any internal leakage in hydraulic or melt systems is a major concern.

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E. Wear / Life Estimation & Risk, Spare Parts & Negotiation

28. Estimate remaining life of critical wear components
    • Based on observed wear in cylinders, seals, guide runners, accumulator parts, extruder screw/barrel — judge how much life remains and how soon parts may fail.
    • If many wear parts are near end of life, refurbishment cost may become prohibitive.
29. Availability of spare parts, support, control parts
    • For Cincinnati / Milacron legacy machines, check whether spare hydraulics, seals, control modules, PLC parts, accumulators, extruder parts, heads, etc. are still available or can be sourced.
    • If parts are obsolete or rare, factor that risk heavily.
30. Refurbishment cost feasibility
    • For identified defects (e.g. re-machining platen, replacing cylinders/seals, control repair, accumulator rebuild) obtain rough cost estimates.
    • Compare cost + risk vs discount you can negotiate.
31. Safety / compliance upgrade cost
    • If safety guards / interlocks / controls are inadequate or non-compliant, estimate cost to retrofit to your jurisdiction’s standards.
32. Transport, reassembly & alignment risk
    • Heavy blow molding machines are subject to misalignment or damage during moving. On delivery, recheck all alignments, hydraulic calibrations, platen flatness, etc., before accepting.
    • Ensure you reserve the right to reject or adjust after installation if performance is not as promised.
33. Acceptance clause / test period
    • Negotiate a clause allowing you to run acceptance tests (including under load) after installation, with the right to reject or demand adjustments / compensation if performance is unsatisfactory.
34. Price negotiation based on deficiencies
    • For every defect or risk you detect, assign a repair cost and deduct from the seller’s asking price or demand the seller fixes them before shipping.
    • If multiple critical defects exist, you may walk away unless the discount is large.

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Red Flags & “Deal Killers” to Watch For

When you inspect, these signs are especially worrisome and may push the machine into “too risky to buy” territory:

• Significant leakage in hydraulic / accumulator / cylinder systems (especially internal leakage)
• Jerky, inconsistent motion of platen, cylinders, guides
• Mismatch of cycle timing or synchronization problems in accumulator head or mold cycle
• Severe wear, scoring or damage in platen, tie rods, guide surfaces
• Extruder screw / barrel with heavy wear, erosion, pitting — excessive clearance
• Control system failure, missing or broken controller modules, or obsolete electronics with no spares
• Cracked or repaired frame / platen structure
• Evidence of heat damage, distortion, welding repairs in critical zones
• Hydraulics or valves in extremely degraded condition, unstable pressure behavior
• Seller refuses to allow running tests, sample molding, or verification of performance
• No documentation, missing schematics, missing manuals or parts lists
• Safety systems missing, guards removed, interlocks bypassed

Any one of these may be acceptable if discounted properly or fixable, but combinations are dangerous.

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How to Incorporate These into Your Decision & Pricing

• Quantify repair/refurbishment costs — for each defect you detect, estimate (or ask vendors) how much to fix.
• Use “as-found” measurements to benchmark your discount.
• Require the seller to fix certain items pre-shipment or provide credits.
• Keep a buffer margin for unexpected problems (hidden wear, surprises during transport).
• Demand final acceptance testing after installation — do not accept “blind” delivery.
• Push for warranty / guarantee on key systems (ex: clutch, control, hydraulics) if possible, even for used machines.