Warpage deformation

The product bends or twists after leaving the mold. Warpage deformation has various manifestations: flat products show bowl-shaped or saddle-shaped bending, strip products show bowing or twisting, and box-shaped products show opening dimension changes. The directionality and severity of deformation depend on the distribution pattern of cooling unevenness and the symmetry of molecular orientation. Warpage has hysteresis——it may not be obvious when just out of the mold, and gradually appears after storage for several hours to several days, which brings challenges to production process quality control.

1. Cooling factors: uneven curing shrinkage, uneven cooling, temperature too high at demolding, asymmetric product structure. 2. Preheating factor: The preheating temperature and time of the material (especially thermosetting molding compounds) directly affect its flowability and curing behavior; improper preheating will lead to poor filling or uneven curing, and it is a key control point unique to compression molding. 3. Molding pressure factor: In compression molding, pressure is not only used to overcome flow resistance, but also directly affects the compactness of the product and the degree of fiber impregnation; insufficient pressure is an important cause of product looseness and insufficient strength.

1. Process parameter optimization and adjustment: cool uniformly, lower the demolding temperature, optimize the symmetry of the product structure, add reinforcing ribs. 2. Systematic troubleshooting method: Troubleshooting of compression molding problems follows the order of 'material -> temperature -> pressure -> mold'. First check the preheating and flowability of the material, then verify the mold temperature distribution and curing time, then adjust the molding pressure and mold closing speed, and finally check the mold venting and demolding conditions. 3. Preventive management: Establish standardized process parameter cards and quality control limits for each set of mold/product, and regularly conduct process capability index (CPK) evaluations. For recurring problems, use fishbone diagrams or 5Why analysis to trace the root cause, and solidify the countermeasures as PFMEA control points.

Warpage is the macroscopic bending caused by inconsistent shrinkage of various parts of the product. The solution idea is: achieve uniform cooling of all parts during the cooling stage (cooling water channel optimization), adopt symmetrical layout and isotropic design in structural design (wall thickness and gate position optimization), and reduce shrinkage anisotropy in material selection.