Analysis of Causes of Scratches in Injection Moulds

During the injection mold molding process, the sliding core, ejector pin, ejector pin sleeve, and center pin of the injection molding mold may "scratch".

"Scratching" refers to abnormal wear on the sliding surface. According to the cause, abnormal wear can be classified as follows.

1. Abrasive wear

This form of abnormal wear is prone to occur when there is a difference in hardness between sliding injection mold parts.

This is a phenomenon in which hard materials bite into soft materials, causing scratches and burns.

2. Adhesive wear

This is a form of wear in which the convex parts of the injection mold parts collide with each other, and the parts with the strongest contact are stuck.

3. Fatigue wear

This is a form of fatigue and wear due to repeated movement and stop of injection mold parts.

This is the form of wear when scaly peeling (peeling) occurs.

4. Fretting wear

This is a wear pattern in which crater-like wear occurs when the clearance is relatively small.

Mostly occur in the square key and keyway of the injection mold.

5. Corrosion and wear

This is a form of wear caused by the potential difference between injection mold parts in a corrosive environment such as chemical composition, moisture, and ions generated by the resin.

If a scratch occurs, the cavity and core will be fatally damaged, and there is a direct risk of damage to the mold if the ejector pin or core does not operate properly.

To prevent galling, proper lubrication management or maintenance-free component construction is required.