Improper Mold Vent Groove Depth

Excessively deep venting leads to flash, or excessively shallow venting leads to bubbles. When this defect occurs in products of Process No. 3, it is usually related to a specific process parameter range or equipment status. If it persists, it will directly affect the product qualification rate and production cycle, increasing material loss and rework costs. Timely diagnosis and elimination is a basic requirement for ensuring stable production.

1. Mold design factors: insufficient machining accuracy of vent grooves, wear deepening after long-term use, mold design vent groove depth not adjusted according to material viscosity, and thermal expansion affecting the gap. 2. Preheating factors: The preheating temperature and time of the material (especially thermosetting molding compounds) directly affect its fluidity and curing behavior; improper preheating leads to poor filling or uneven curing, and is a key control point unique to compression molding. 3. Molding pressure factors: 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 wetting; insufficient pressure is an important cause of loose products and insufficient strength.

1. Process parameter optimization and adjustment: Precisely machine the vent groove depth according to material characteristics, regularly check for wear, and consider thermal expansion during design. 2. Systematic troubleshooting method: Troubleshooting of compression molding problems follows the order of "material -> temperature -> pressure -> mold". First check the preheating and fluidity 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 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 countermeasures as PFMEA control points.

This problem is a typical manifestation of improper mold vent groove depth in compression molding. The core of the solution lies in the reasonable preheating of the material and the guarantee of fluidity, as well as the precise matching of mold temperature and molding pressure. It is recommended to make coordinated adjustments from both the material state and process parameters.