Injection Molding Problem: Heat Flow
author: Universe plastic
2024-07-10
Marks In injection molding manufacturing, heat flow marks on plastic parts are a common surface defect problem, usually appearing as streaks, ripples or irregular lines.
These marks will affect the appearance and performance of injection molded products. The following are the causes and solutions of hot flow marks shared by Universe Plastics engineers:

Causes of heat flow marks
1. Melt temperature is too low
When the injection molding melt temperature is too low, the material fluidity is poor and heat flow marks are easily formed in the mold cavity.
2. Injection speed is too low
If the injection speed of the injection molding machine is too low, the injection melt may flow unevenly in the mold and form heat flow marks.
3. Uneven mold temperature
The temperature of the injection mold is too low or uneven, causing the injection melt to cool too quickly in the mold cavity, forming heat flow marks.
4. Mold design issues
Improper design of runners and gates results in uneven melt flow paths.
5. Improper material selection
The material used has poor fluidity, resulting in hot flow marks during injection molding.

Thermal Flow Mark Solution
1. Increase melt temperature
Increase the barrel temperature and nozzle temperature of the injection molding machine to improve the fluidity of the material.
2. Increase injection speed
Increase the injection speed appropriately to quickly fill the mold cavity with melt and reduce the formation of flow marks.
3. Optimize mold temperature
Adjust the mold temperature to distribute it evenly to avoid local cooling too fast.
4. Improve mold design
Redesign the runner and gate to make the melt flow path smoother and reduce flow marks.
5. Choose the right materials
Choose a material with better fluidity, or add lubricant to improve the fluidity of the material.
6. Increase back pressure and holding pressure
Appropriately increasing the back pressure and holding pressure can improve the uniformity of the melt and reduce flow marks.
7. Adjust the cooling time
Depending on the product thickness and material properties, adjust the cooling time to avoid flow marks caused by premature cooling.

Summarize
In actual injection molding production, we can learn from the above methods and combine them with the injection molding environment to continuously optimize the injection molding process to reduce or eliminate the occurrence of heat flow marks and improve the appearance quality and performance of injection molded products.
Dongguan Universe Plastic Factory has more than 15 years of injection molding experience, a professional injection molding team and advanced injection molding equipment, providing professional and cost-effective one-stop injection molding services.
If you are looking for an excellent injection molding factory, please contact us to get the latest service prices.
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