Product creep

The product dimensions slowly change under long-term load. When this defect occurs in products of Process No. 2, 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 to ensure stable production.

1. Reaction process factor: Insufficient crosslinking density, the use temperature is close to the glass transition temperature, low hard segment content, and insufficient post-curing. 2. Mixing quality factor: In the RIM process, the mixing uniformity of the two components is the foundation of all quality; the Reynolds number of the mixing head, the impingement mixing energy, and the residence time distribution are the key engineering parameters that determine the mixing quality.

1. Process parameter optimization and adjustment: Increase the crosslinking density, increase the hard segment content, fully post-cure, and reduce the use temperature. 2. Systematic troubleshooting method: RIM problem troubleshooting follows the order of "formulation -> mixing -> temperature control -> equipment". First check the two-component ratio and catalyst dosage, then check the mixing head and self-cleaning function, next troubleshoot the raw material and mold temperature control, and finally check the accuracy of the metering pump and hydraulic system. 3. Preventive management: Establish standardized process parameter cards and quality control limits for each mold/product, and regularly conduct process capability index (CPK) assessments. 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 product creep in the RIM process, and the core of the solution lies in ensuring the precise ratio and sufficient mixing of the two components, while controlling the reaction temperature and curing conditions within the optimal window. It is recommended to start troubleshooting from the mixing system and metering accuracy.