Why does the injection molding machine break when ejecting?

The occurrence of injection molded products breaking during ejection or showing susceptibility to breakage can stem from various factors, which I'll break down into operational, product design, and mold design aspects:

Operational Aspect:

1. Improper Ejection Force Control: It's possible that the ejection force isn't calibrated correctly, leading to excessive force during ejection, thus causing the product to crack.
2. Inappropriate Ejection Timing: If the ejection timing isn't set correctly, the product might be ejected prematurely before it's fully cooled and solidified, increasing the risk of breakage.
3. Uneven Temperature Control: Uneven temperature distribution within the injection molding machine can result in premature solidification in some areas and delayed solidification in others, potentially causing stress concentrations and subsequent cracking during ejection.

Product Design Aspect:

1. Uneven Wall Thickness Design: Inadequate uniformity in wall thickness across the product can lead to stress concentrations during ejection, especially if certain areas have excessively thick or thin walls.
2. Structural Design Flaws: Poor structural design, such as sharp internal corners or overly fragile sections, can create weak points prone to cracking during ejection.
3. Inappropriate Material Selection: If the chosen material doesn't align with the product's design requirements or if the material quality is subpar, it can contribute to product breakage during ejection.

Mold Design Aspect:

1. Inadequate Venting: Insufficient venting channels in the mold design can result in trapped air or gas during ejection, leading to air pockets or voids in the product and subsequent breakage.
2. Improper Mold Surface Treatment: A rough or flawed surface finish on the mold can damage the product during ejection, increasing the risk of cracking.

Addressing these factors comprehensively, considering both operational adjustments and design enhancements, can significantly mitigate the risk of product breakage during ejection in injection molding processes.