How to Judge Whether a Twin-Screw Extruder Die Needs Replacement

We can determine whether to replace the twin-screw extruder die from three practical dimensions: production operating conditions, discharging performance, and physical wear condition. The judgment standards are clear, intuitive and suitable for on-site operation.
1. Judgment from Finished Product & Discharging Status (Most Intuitive)
Abnormal Discharging Performance
Unstable discharging speed with frequent fluctuation; uneven material output from each die hole, accompanied by partial hole material breakage or no discharge. The extruded material diverges and fails to form a regular shape, with obvious deviation in the size and thickness of finished products.
Declined Product Quality
Finished products feature rough surfaces, excessive burrs and frequent cracks. Special-shaped dies (bone-shaped, star-shaped, etc.) suffer from outline deformation and corner missing. Under consistent process parameters, the product expansion degree and density become unstable, leading to a sharp rise in defective rate.
Reduced Production Capacity
Under fixed rotating speed, temperature and raw material conditions, the overall machine output drops significantly, and the problem cannot be improved by adjusting process parameters.
2. Judgment from Die Appearance & Physical Wear
Die Hole Wear
Obvious drawing marks and hole expansion appear on the inner wall of die holes, and the aperture size exceeds the standard tolerance range. Round holes turn elliptical, and the outline of special-shaped holes is severely worn and distorted, which is irreparable and requires replacement.
Damage & Defects
Chipping, edge collapsing, block falling and cracks occur on the die orifice. The die body is deformed and warped, failing to fit tightly after installation and causing continuous material leakage.
Corrosion & Rust
Deep rust and pitting corrosion appear on die holes and working surfaces. The surface smoothness cannot be restored even after oilstone grinding and polishing, which adversely affects normal discharging and molding.
3. Judgment from Operation & Maintenance Cost
Frequent Malfunctions
Frequent hole blockage and material adhesion occur in a short period. A large amount of working time is consumed on daily cleaning and grinding, resulting in a sharp increase in maintenance time and cost.
Invalid Repair & Polishing
Problems persist after repeated polishing, deburring and shape correction. Partial repair fails to solve the problem thoroughly, and damage recurs in a short time after fixing.
Expired Service Life
Each conventional extrusion die has a rated service life. For long-term high-frequency operation (e.g., 24-hour continuous production), it is recommended to replace the die directly once it reaches the manufacturer’s specified service life, so as to avoid unplanned shutdown caused by sudden failures.
Supplementary Distinction: Repairable vs. Mandatory Replacement
? Repairable Conditions: Slight burrs, shallow rust stains and minor surface scratches (can be fixed by oilstone grinding and fine polishing).
? Mandatory Replacement Conditions: Aperture size out of tolerance, die body cracking/deformation, large-area edge chipping and damage, deep pitting corrosion, and persistent production abnormalities that cannot be eliminated after repeated maintenance and polishing.