Rapid temperature rise in injection molding: impact and countermeasures


Rapid temperature rise during injection molding can lead to a series of adverse effects, significantly impacting product quality, mold longevity, and production efficiency. To effectively address these issues, it is crucial to implement appropriate temperature control measures.


Impact of rapid temperature rise

1. Product defects:

A. Burning: premature decomposition of molten plastic generates gases and scorch marks, resulting in a rough, discolored, and odorous product surface.

B. Blisters: Entrapped moisture and volatiles in the molten plastic form bubbles, causing surface imperfections on the molded part.

C. Wrapping: uneven cooling rates between the plastics interior and exterior lead to non-uniform shrinkage, causing the product to warp or deform.

D. Cracking: localized overheating softens the plastic, making it susceptible to cracks under the compression forces of mold shrinkage.


2. Mold damage

A. Corrosion: elevated temperatures accelerate mold corrosion, reducing its lifespan.

B. Deformation: excessive thermal stress can cause mold deformation, compromising product accuracy.


3. Reduced production efficiency

A. Extended cooling time: higher temperatures prolong product cooling time, hindering production efficiency.

B. Increased reject rate: the aforementioned product defects contribute to a higher reject rate, leading to material waste.


Countermeasures for effective temperature control:

1. Controlled heating temperature: select an appropriate heating temperature based on the plastics thermal properties and implement a gradual heating process.

2. Enhanced cooling: increase coolant flow rate and velocity to shorten cooling time.

3. Mold temperature control system: utilize a precise mold temperature control system to ensure uniform temperature distribution.

4. Suitable additives: employ additives that enhance the plastics thermal stability and minimize decomposition.


Temperature control plays a pivotal role in injection molding. Rapid temperature rise can trigger a cascade of detrimental effects, jeopardizing product quality, mold integrity, and product efficiency. Therefore, implementing effective temperature control measures is paramount for ensuring a smooth and successful injection molding process.

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