ما هو الحد الأقصى المسموح به لتفاوتات أجزاء هيكل الطائرة المصبوبة؟
What Is the Maximum Allowable Tolerance for Airframe Cast Parts?
Industry Tolerance Standards for Airframe Castings
For aluminum cast components used in airframe structures, the maximum allowable dimensional tolerance depends on the size, geometry, and functional criticality of the part. According to aerospace standards such as NADCAP, AMS 2175, and SAE AS specifications, the typical maximum as-cast tolerances for high-integrity aerospace aluminum alloys (e.g., A356, AlSi10Mg) are:
±0.25 mm for dimensions under 25 mm
±0.40 mm for dimensions between 25–100 mm
Up to ±0.75 mm for large, non-critical dimensions over 300 mm
For critical features—such as mounting interfaces, load-bearing sections, aerodynamic components, and sealing surfaces—tolerances as tight as ±0.05 mm to ±0.10 mm are often required. Such precision is typically achieved through CNC post-machining rather than through the as-cast process.
Factors Influencing Tolerance Capabilities
Dimensional accuracy in aerospace castings is influenced by several key factors:
Alloy shrinkage and solidification behavior: Alloys such as A360 and AlZn10Si8Mg produce more predictable shrinkage and minimal warpage during cooling.
Tool and die precision: High-precision molds and dies with controlled thermal management are essential for repeatable tolerances.
Process control: Tight control of injection pressure, cycle time, melt quality, and mold temperature ensures dimensional consistency across batches.
Inspection capability: Advanced quality checks—such as CMM measurement, X-ray/NDT, and CT scanning—are used to validate dimensional accuracy and internal integrity.
Compliance with Aerospace Standards
Airframe cast parts must meet strict requirements defined by AS9100 and OEM-specific standards such as Boeing BAC, Airbus ABR, and MIL-STD-2175. These standards specify allowable tolerance bands, casting integrity levels (Levels A–D), and mandatory inspection protocols. Features outside critical tolerance ranges typically undergo CNC refinement to achieve final specification.
Recommended Services to Ensure Tolerance Control in Airframe Castings
Neway provides precision aerospace manufacturing support through:
Tool and Die Making: High-precision aerospace molds with optimized thermal and dimensional stability.
Post-Machining Services: CNC finishing to achieve tight tolerance requirements for critical airframe interfaces.
Dimensional & NDT Inspection: CMM, X-ray, and CT scanning to ensure full compliance with aerospace tolerance and integrity standards.
These capabilities ensure consistent dimensional reliability for airframe-grade castings in demanding aerospace applications.
