In the refrigerator production process, polyurethane foaming technology is widely used for insulation filling of refrigerator doors. However, in actual operation, problems such as deformation, bulging or warping of refrigerator doors after foaming sometimes occur , which not only affects the appearance of the product, but also reduces the sealing performance and energy efficiency.
1. The main reason for the deformation of refrigerator door after foaming
- Uneven foaming and expansion
Polyurethane releases heat and expands during the reaction foaming process. If the temperature or pressure in the mold is unevenly distributed, it is easy to cause the material to expand excessively or insufficiently in local areas, causing deformation of the door panel. - Mold design or closure problems
If the mold structure design is unreasonable (such as unscientific rib arrangement and poor exhaust), or the mold is not closed tightly, it may also cause asymmetric expansion of the door body, resulting in warping. - Imprecise control of foaming dosage
, unbalanced mixing ratio of foaming raw materials or uneven injection can easily lead to incomplete filling or local excessive foaming, resulting in internal stress changes and causing deformation. - Improper control of cooling and demoulding time,
forced demoulding before the foam is fully solidified, or failure to effectively support cooling and shaping after demoulding can also cause the door body to deform under shrinkage stress.
2. Effective measures to solve the foaming and deformation of refrigerator doors
Process control:
- Precisely control the foaming temperature and pressure
to keep the injection port material temperature and mold temperature stable, ensure that the foaming reaction process is controlled, and avoid local overheating or under-foaming. - Reasonably control the injection time and amount.
Set the appropriate injection program according to the mold cavity size and door panel structure to prevent hollowing or incomplete filling due to insufficient pressure or insufficient material amount.
Structural design:
- Optimize the mold structure
to adjust the rib layout in the easily deformed area, optimize the cavity exhaust channel, and improve the foaming uniformity and mold closing accuracy. - The mold closing force and positioning system are regularly calibrated
to avoid asymmetric expansion of the structure caused by mold misalignment or loose closure.
3. Daily suggestions for preventing refrigerator door foaming and deformation
- Regularly maintain molds and foaming equipment , such as high-pressure mixing heads, mold temperature controllers, pressure control systems, etc., to ensure that the equipment is in good condition;
- Strictly control the raw material storage temperature and ratio accuracy to prevent uneven mixing due to changes in raw material viscosity;
- Use high-quality polyurethane systems with fine pores and smooth expansion , such as the refrigerator-specific foaming materials provided by our PUGLUE, which have stable formulas, good fluidity, uniform pore structure, and effectively reduce deformation rate.