Why Can't Free-Form Curved GRC Panels Use Traditional Wooden Molds?

In the field of GRC special-shaped component manufacturing, the production of freeform (especially double-curved) components poses an extreme challenge to mold precision and stability. Traditional wooden molds fall short fundamentally because of three inherent defects: material limitations, insufficient machining precision, and poor stability. As Qinglong Group, with 28 years of GRC production experience, we have long since fully adopted high-precision CNC technology in place of traditional wooden mold processes in large double-curved curtain wall projects such as the Nanning New Media Center, ensuring the precise realization of every complex GRC panel.

The primary problem with traditional wooden molds is that the material's deformation is uncontrollable. As a natural material, wood is highly sensitive to changes in temperature and humidity and is prone to expansion, contraction, and warping. In the GRC production process, cement hydration releases heat, and the steam curing environment is high-temperature and high-humidity, so wooden molds deform easily, causing dimensional deviations in components and loss of control over surface flatness. The geometry of freeform surfaces demands highly stable molds; the slightest deformation will cause assembly to fail. The high-density wood-substitute or epoxy resin molds used by Qinglong have a coefficient of thermal expansion far lower than that of wood, effectively resisting the effects of the production environment.

Another critical flaw is that machining precision cannot meet the demands of freeform surfaces. Traditional woodworking of complex curved surfaces relies mainly on the craftsman's handiwork, making millimeter-level precision control difficult to guarantee, let alone achieving mathematically exact continuous surfaces. In modern architectural design, many double-curved surfaces are NURBS surfaces generated by parametric algorithms and must be digitally machined on five-axis CNC machines to ensure precision. The five-axis CNC systems introduced by Qinglong achieve machining precision of up to ±0.1mm—beyond the reach of any traditional woodworking skill.

Economy and durability are also important considerations. Although wooden molds have a lower initial cost, they have a short service life, and their precision drops sharply with repeated use. For projects that require dozens or even hundreds of similar but not identical components (such as the Nanning New Media Center), the total cost of producing large numbers of single-use wooden molds actually far exceeds that of one set of high-quality steel or resin molds. Through digital mold technology, Qinglong has achieved flexible production with 'one mold, multiple uses,' which is more economical over the full life cycle. Therefore, abandoning traditional wooden molds is an inevitable choice for the GRC industry as it develops toward high precision and high efficiency.