How to inspect screw and barrel wear and clearance for acceptance of an extruder?

• Measure barrel ID with inside micrometer; radial clearance vs new screw OD should be ≤0.15% of barrel ID.
• Check screw flight wear; over 0.3mm requires nitriding repair or replacement.
• Verify barrel straightness with plug gauge; full-length deviation should be ≤0.05mm.
• Request screw hardness report: nitrided case 0.4-0.7mm deep, hardness ≥900HV.
• Run no-load test and check current fluctuation; over 10% indicates excessive clearance or bent screw.