In the production of refrigerator doors or boxes, core-pulling structures are often used to form complex areas such as internal reinforcement ribs, edge-sealing grooves, hinges, etc. If the core-pulling mechanism of the mold does not operate properly, it will directly affect the dimensional stability and appearance quality of the product, and in serious cases, it may even cause subsequent problems such as interference in the assembly of the entire machine and sealing failure.
This article will combine the structural characteristics of refrigerator molds to deeply analyze the impact of inadequate core pulling on the refrigerator shell , and provide targeted optimization suggestions.
Typical effects of mold core pulling not being in place
1. Insufficient core pulling force, difficult demoulding
When the mold is opened, if the core pulling system has insufficient thrust or incomplete action , the core will be forcibly detached before the product is fully cooled, causing stress concentration and product deformation.
Common reasons include:
the inclined guide column is too large, resulting in large core pulling resistance
Insufficient thrust or pressure relief in hydraulic/pneumatic core pulling system
The slider stroke is limited and does not reach the set demoulding position
Results: Surface stretching and local distortion of the product, especially at the edges and corners of the door.
2. Insufficient mold strength and structural deformation
If the template thickness is insufficient or the rib design is unreasonable, the mold body will slightly bend or accumulate deformation during the core pulling process . Although this type of deformation is not easy to detect at the mold end, it is directly transferred to the product, causing an asymmetrical or misaligned appearance.
Result: The dimensional deviation of the door or the rear structure of the box affects the assembly accuracy and sealing performance.
3. Uneven cooling and unbalanced shrinkage
If the mold cooling in the core pulling area is not designed properly, it is very easy to cause different cooling speeds in different parts , which will eventually lead to different shrinkage degrees of the plastic or PU foam, resulting in warping, dents and other problems when the product releases internal stress.
Results: The door edge was slightly twisted, the cabinet panel was bent, and the appearance quality was reduced.
Countermeasures: Multi-dimensional optimization from design to process
Optimize mold structure design
- Accurately calculate the core pulling thrust requirements and reasonably design the angle of the inclined guide column (it is recommended to be controlled at 10°~15°)
- For the long core-pulling slider area, add auxiliary slide rails or clamping positioning mechanism
- Strengthen the formwork structure, appropriately thicken or add reinforcing ribs to improve flexural strength
Improve processing and assembly accuracy
- Ensure that the clearance of key components such as guide pillars, sliders, and core pulling plates is within a reasonable range (generally ≤0.05mm)
- Prevents jamming or deviation during core pulling due to processing errors
- Regularly check the movement trajectory of the slider to avoid interference or abnormal wear
Controlling injection molding and foaming process parameters
- In injection molding, properly control the holding time and cooling time to avoid premature demoulding.
- During foaming, ensure that the core is pulled out before starting the injection to avoid uneven PU filling.
- The cooling system layout should cover the key core pulling area to ensure uniform temperature of the entire mold
Conclusion
The failure of the refrigerator mold to pull the core properly may seem like a small action, but it affects the stability of the entire product structure. Only through the coordinated efforts of precise design, standardized processing and optimized technology can the problems of product deformation and poor size be eliminated from the source.
If your mold has abnormal core pulling or product deformation during use, please contact our technical team. We can provide on-site diagnosis, mold optimization and transformation and upgrading services to help you achieve more efficient and stable refrigerator foam molding production.