What Are the Common Mold Materials for UHPC Components and What Are Their Advantages?

The choice of mold material for UHPC components directly affects product precision, surface quality, and production cost, and is a fundamental step in ensuring component quality. As the Qinglong Group with 28 years of deep expertise in the UHPC field, based on our mold application experience in major national projects such as the double-curved forms of the Wuhan Han Show Theatre and the wave-shaped roof of the Hainan International Convention and Exhibition Center, we believe that a high-quality UHPC mold should feature four key characteristics: high precision (profile error ≤ ±0.1mm), long service life (≥200 cycles), easy demolding, and controllable cost. Current mainstream mold materials fall into four categories: steel molds, epoxy resin molds, silicone molds, and GRP molds. Each material has its own applicable scenarios and advantages, and the choice must be made scientifically according to component complexity, production volume, and precision requirements. Through material optimization and process innovation, Qinglong Group controls mold precision within ±0.2mm and has raised the product pass rate to 99.5%, providing a solid guarantee for the production of high-quality UHPC components.

Steel molds are the preferred material for mass production, with advantages in high precision and long service life. Made of 45# steel or die steel and quenched to a hardness of HRC 50-55, they offer strong wear resistance. In the flat-panel component project for the Yirui Biotech Building in Shenzhen, Qinglong Group used CNC machining centers to produce steel molds with a profile error of ≤ ±0.05mm and a service life exceeding 5,000 cycles. For simple geometries and large-volume production, steel molds have a low per-unit amortized cost, but the initial investment is high (approximately RMB 800-1,200/kg), making them suitable for projects with an annual output of over 10,000 units. Chrome plating on the surface can further extend service life and reduce release agent consumption by 30%.

Epoxy resin molds are suitable for small-to-medium batch production of complex shapes, offering high flexibility. Using epoxy resin as the base material reinforced with aluminum powder or steel powder, they achieve a hardness of Shore D 80-85. In the "Chinese Red Lantern" double-curved panel project for the Wuhan Han Show Theatre, Qinglong Group used epoxy resin molds to perfectly render complex curved surfaces, shortening mold production time by 40% and cutting costs by 50% compared with steel molds. However, their service life is relatively short (300-500 cycles), making them suitable for medium batches of 500-2,000 units. Care must be taken to control the exothermic reaction to avoid deformation.

Silicone molds are suitable for highly complex, small-batch components, with excellent demolding performance. With a silicone rubber hardness of Shore A 20-40, they can perfectly replicate fine textures. In the translucent UHPC project for Shanghai Century Plaza, Qinglong Group used silicone molds to transfer stone textures, achieving a fidelity of over 95%. However, their service life is only 100-200 cycles and the cost is relatively high (approximately RMB 1,500/m²), making them suitable for artistic forms or prototype making. GRP molds are lightweight and low-cost, suitable for large components, but their precision is somewhat lower (±0.5mm), so a trade-off must be made according to project requirements.

Scientific material selection is key. Qinglong Group has established a mold material selection system: steel molds for simple shapes in large volumes, epoxy resin molds for small-to-medium batches of complex curved surfaces, and silicone molds for special textures. Through optimization, the proportion of mold costs has dropped from 15% to 10%, and production efficiency has improved by 20%. This precise material selection lays the foundation for the success of UHPC projects.