Precision Molds Empower The R&D Of Aeronautical Components

With the accelerated advancement of projects such as large-scale aircraft, civil drones and eVTOLs, precision composite forming molds serve as core tooling for the development of composite components. They directly determine the dimensional accuracy of samples, internal porosity defects and assembly compatibility, and have become a critical bottleneck for aerospace composites transitioning from laboratory-based R&D to airworthiness certification and small-batch trial production. Domestic mold enterprises have made continuous breakthroughs in autoclave tooling, aerospace-grade RTM precision molds, low-expansion Invar molds and carbon-fiber tooling. These advances shorten the R&D cycle for aeronautical composite components, cut trial-and-error costs and accelerate the localization of the aerospace composite industrial chain.

I. Process Dimensions

1.Aerospace composite components are subject to stringent airworthiness access requirements, imposing rigorous mandatory standards on core indicators including forming dimensional tolerances, cavity vacuum tightness, full-domain temperature-field uniformity and component porosity. Supported by a complete set of digital and precision-oriented process measures, a R&D-and-manufacturing system for aerospace composite molds featuring "high precision, low defects, iterative capability and stable mass production" has been established. It comprehensively improves the development efficiency and quality stability of composite components.

2.Pre-judgment of processes via CAE simulation：At the mold-design stage, simulation analyses covering curing deformation, thermo-mechanical coupling and temperature-field distribution are introduced to predict potential defects during composite forming, such as warpage, uneven temperature gradients and abnormal resin flow. Physical trial-and-error molding is reduced, shortening the component R&D cycle by over 30% and significantly cutting development costs for trial runs.

3.Five-axis linkage high-speed machining process：Adopting one-setup integrated five-axis machining, precision milling is performed for large-size cavities with complex curved surfaces. Cumulative positioning errors caused by repeated re-clamping are completely eliminated, precisely meeting forming requirements for complex aerodynamic profiles and high-precision curved surfaces of aerospace components.

4.Closed-loop inspection process combining 3D scanning and coordinate measuring machines (CMM)：A full-process precision-inspection closed loop is established. Upon mold completion, full-dimensional accuracy verification is carried out with 3D-scanning and CMM equipment. After trial molding, reverse-engineering scanning and modeling are performed on composite parts. Cavity parameters are modified according to data on curing shrinkage and deformation, realizing full-link closed-loop optimization of "design-machining-inspection-compensation". This is an indispensable process for compliant R&D of aerospace composite components.

5.Modular insert-assembly process：For molds of extra-large aerospace panel-type components, segmented insert-assembled modular composite structures are adopted. This effectively addresses long-standing industry challenges for monolithic large molds, such as difficult machining, high residual heat-treatment stress and proneness to deformation. When component structures require iteration and optimization, only local inserts need replacement instead of full mold remanufacturing. The solution well adapts to high-frequency R&D iterations of aerospace products and reduces modification costs.

II. Technical Dimensions

(1) Iteration of mold base material technology

The forming accuracy and stability of aerospace composite components rely heavily on the performance of high-grade mold substrate materials. With continuous upgrades in domestic aerospace tooling technology, mold substrates have achieved differentiated, localized and high-performance improvements, targeting key challenges such as composite curing deformation, dimensional deviation and cost control. A substrate-selection system matching diverse R&D and mass-production scenarios has been formed.

Invar alloy substrate：Its coefficient of thermal expansion closely matches that of carbon-fiber composites, offsetting deformation deviations arising from composite curing to the maximum extent. It acts as the standard core tooling material for mass-production of primary load-bearing aerospace components. Domestic breakthroughs have been realized for Invar blank materials, breaking overseas monopolies.

Carbon‑fiber BMI resin mold substrate：It delivers dual advantages of light‑weight tooling and well‑matched thermal expansion properties, effectively mitigating overall deformation during forming of large‑size parts. Especially suitable for R&D and trial‑manufacturing of extra‑large, high‑curvature aerospace composite components, it balances forming accuracy and tooling adaptability and ranks among preferred substrates for manufacturing large‑scale aerospace composite parts.

Hybrid Invar-steel tooling：Currently the mainstream solution deployed for domestic aerospace composite R&D projects, it features a composite structure combining precision-formed Invar face sheets and high-strength steel back-plates. This design strikes an optimal balance among forming accuracy, tooling rigidity and manufacturing costs. The Invar face sheets guarantee thermal-matching precision for composite forming, while steel back-plates enhance overall mold rigidity and lower material consumption costs. It fits most R&D and small-batch trial-production scenarios for aerospace secondary-load-bearing and key structural components.

(2) Digital Full-Process R&D System

Driven by in-depth digital-technology enablement, the industry has built a full-process closed-loop R&D system that realizes end-to-end data connectivity and intelligent optimization from design to verification.

The complete system covers DFM (Design for Manufacturability) formability analysis for components, structural design of precision molds, composite curing simulation, five-axis precision machining, full-dimensional 3D inspection and trial-molding verification & optimization. Virtual-simulation technology identifies forming defects, structural deviations, abnormal resin flow and other issues in advance, replacing conventional physical trial-and-error and drastically reducing prototype iterations and R&D cycles. On this basis, digital-twin technology is applied. High-precision temperature and pressure sensors mounted on molds collect real-time forming-condition data fed into simulation systems. Actual trial-molding data iteratively optimizes mold runner, temperature-control and sealing-structure designs. A positive cycle of "virtual simulation - physical machining - data feedback - continuous optimization" is created, comprehensively lifting design precision and forming stability for aerospace composite molds.