Common causes and solutions for refrigerator molds with incomplete foaming and insufficient corner filling

1. The mold is not closed tightly or the exhaust is not smooth

Cause analysis : The mold parting surface is worn or misaligned, which may cause the foaming material to escape from the gap, resulting in insufficient foaming volume. On the other hand, if the exhaust groove is blocked or the number is insufficient, the gas generated by foaming is difficult to discharge, forming “back pressure” and affecting the filling of the foam.

Solution :

• Check the matching accuracy of the mold parting surface to ensure tight closure;
• Clean the exhaust slots regularly and add exhaust holes when necessary;
• Be careful not to block the vent when using mold release agent.

2. Improper process parameter settings

Cause analysis : Insufficient foaming pressure or spraying speed will lead to reduced fluidity of the raw materials, especially in complex structures or corner areas, which are difficult to fully fill; in addition, if the mold or raw material temperature is too low, it will also affect the expansion and foaming reaction of the foam material.

Solution :

• Increase the injection/ejection pressure and speed to improve the ability of the foam to reach the dead corner area;
• Keep the mold temperature within a reasonable range (35–45°C is generally recommended);
• Increase the temperature of raw materials to ensure that the viscosity of materials A and B is moderate and the reaction activity is stable.

3. Abnormal material fluidity or formulation problems

Cause analysis : If the proportion of catalyst in the formula is too high, it will lead to too fast reaction, and the foam material will solidify before it is completely diffused, resulting in incomplete foaming; some low-viscosity systems (such as adding too much cross-linking agent or silicone oil) have too strong fluidity and are also easy to leak out from the gaps.

Solution :

• Properly adjust the catalyst ratio to control the reaction rate;
• Optimize the amount of silicone oil and cross-linking agent according to the mold structure to avoid leakage;
• Use low-resilience or closed-cell polyurethane systems that are more suitable for this structure.

4. Unreasonable gate design

Cause analysis : Improper gate position or too small cross-sectional area will limit the path of the foam material entering the mold cavity and prevent it from flowing into the far end or corner area in time.

Solution :

• Optimize gate layout to give priority to raw material supply in remote and thin-walled areas;
• Increase the diameter of the main channel and the branch channel to increase the foam material flow rate;
• Try gating at multiple points or using dynamic gating technology to improve distribution uniformity.

5. Uneven mold temperature distribution

Cause analysis : The temperature of some parts of the mold is low, which causes the raw materials to solidify prematurely and hinders the subsequent flow of foam materials, especially in the corners, which is more prone to insufficient filling.

Solution :

• Check whether there are dead spots or unstable temperature control in the mold temperature control system;
• For corner areas, local electric heating or hot water circulation can be added;
• Optimize the mold insulation layer to ensure overall temperature balance.

Summarize

The problem of refrigerator molds not being fully foamed or not filling the corners is often caused by multiple factors. It is recommended that companies conduct mold inspection, process optimization and material evaluation before foaming production to prevent problems from occurring fundamentally. At the same time, automatic detection and AI process optimization systems can be combined to improve the first-time pass rate and reduce production losses.

If you need further diagnosis of specific mold problems or support for customized foaming process parameters, please contact our technical engineering team and we will provide one-on-one optimization services.