Hollow Lightweight
Structural Parts

Practical minimum: 0.8 mm for Al 7075, 1.0 mm for Al 6061, 0.8 mm for Ti Grade 5, 1.2 mm for stainless. Below these limits, chatter and clamping distortion make consistent wall thickness impossible. HXC flags thin-wall concerns in the DFM review and recommends the optimal minimum for your geometry.

HXC uses a combination of CMM measurement at accessible surfaces and calibrated ultrasonic wall thickness gauge for enclosed cavities. Wall thickness is measured at multiple angular positions and axial stations — all reported on the inspection certificate.

A properly designed hollow part in Al 7075 can be 40–60% lighter than a solid part of the same external dimensions. Ti Grade 5 hollow structures are 30–40% lighter than equivalent aluminium solid parts while offering higher specific stiffness. The exact reduction depends on the load path and minimum wall constraint.

Three strategies: (1) Staged roughing and finishing — rough cut removes most material with high stiffness, then walls are finish-machined in light passes. (2) Temperature-stabilised clamping — hydraulic fixtures apply uniform, low clamping force. (3) Sequence optimisation — walls are machined in an order that retains the most surrounding material as long as possible.

T6 temper (solution heat treatment + artificial ageing) is standard for Al 7075 — provides peak strength. For thin-wall hollow parts, we machine to T651 pre-tempered stock and avoid re-ageing after machining to minimise distortion. If post-machining anodizing is required, dimensional compensation is applied before anodizing.

Yes — internal pockets, channels, and bosses are machined using extended-reach tooling and 5-axis access angles. Surface finish inside cavities: Ra 0.8–1.6 µm standard. For critical internal surfaces (bearing seats, seal grooves), Ra 0.4 µm is achievable. Blind internal features are verified using articulated CMM probes.

Hard anodizing (Type III): 15–25 µm on Al alloys — significant hardness improvement without distorting thin walls. Chromate conversion coating: minimal thickness, for aerospace primer adhesion. Electroless nickel: uniform internal and external coating for corrosion protection. Avoid heavy plating processes (>10 µm) on thin-wall parts.

Prototype (complex hollow, custom fixturing): 7–12 days. Small batch: 12–18 days. UAV frame production runs: 15–22 days. Ti Grade 5 hollow structures add 3–5 days for material lead time and slower cutting parameters.