Buying a used injection molding machine can save 40-60% vs new but only if you ask the right questions first.

1. What is the actual service history?
Look for documented oil changes, screw/barrel replacement, hydraulic filter changes. Missing logs = higher risk.

2. Has the screw or barrel been replaced?
Screw OD wear over 0.5mm reduces performance significantly. New barrel costs 2000-8000; new screw costs 800-3000.

3. What is the tie-bar tension reading?
Uneven tension (20%+ variation between bars) indicates uneven loading. Can be re-tensioned, but check for platen damage.

4. Is the injection unit aligned properly?
Check nozzle centerline alignment to the stationary platen. Misalignment causes excessive wear on guide bushings.

5. What controller is installed?
Older controllers prior to 2015 may have obsolete parts. Verify manuals and backup files are included.

6. How does the hydraulic system look?
Check for oil discoloration (milky = water contamination). Listen for pump cavitation during dry cycle. Check all hoses for cracks near fittings.

7. Are spare parts and documentation included?
A set of spare heater bands and seals is valuable. Ask for electrical schematics and hydraulic diagrams.

Final Tip: Bring a mold you already run successfully and do a trial run. A 30-minute test can save you thousands in surprises.

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