In long-term use, the accuracy of the mold will decrease due to wear and corrosion, and it is necessary to establish a regular maintenance mechanism to maintain the accuracy and stability of the cavity and core.

1. Routine Maintenance: Reduce wear and corrosion

Cleaning and rust prevention: After each production, clean the cavity/core surface with a special cleaning agent (such as neutral release agent cleaner) to remove the residual PET melt (to avoid scratching the surface after high-temperature carbonization). When not in use for a long time, spray anti-rust oil (choose food-grade anti-rust oil to avoid polluting raw materials);
Wear monitoring: For every 50,000 to 100,000 preforms produced, the key dimensions of the cavity/core (e.g., thread height, cavity inner diameter) are checked, and if the wear amount exceeds 0.01mm, "repair machining" (e.g., chrome plating thickening of the inner wall of the cavity, re-welding and regrinding of the core surface) is required.

2. Restoration and Refurbishment: Restore precision

Minor wear repair: If there are small scratches on the surface of the cavity (depth ≤ 0.005mm), use "local polishing" (use diamond abrasive paste, particle size W1-W3) to restore the surface finish;

Moderate wear repair: If the thread tooth height is worn 0.01-0.02mm, use a thread grinder for "micro grinding" (removal amount ≤ 0.01mm) to recalibrate the thread accuracy;

Severe wear treatment: If the inner diameter of the cavity is worn more than 0.02mm, the cavity insert needs to be replaced (using the same material and processing technology as the original mold to ensure the dimensional consistency between the new insert and the old mold).