Surface Finishing Aerospace Castings: Methods Guide
TL;DR: Surface finishing aerospace castings turns an as-cast part into a functional finish. Investment casting starts around Ra 1.6 to 3.2 micrometres, improved further by shot blasting, machining, polishing, or anodizing.
Surface finishing aerospace castings sets both appearance and performance. Good surface finishing aerospace castings improves corrosion resistance, fatigue life, and coating adhesion. It builds on our near-net-shape investment casting.
What Is Surface Finishing for Aerospace Castings?
Surface finishing covers every step that improves a casting’s surface after pouring. It ranges from cleaning off shell residue to precise machining and coating, all chosen to meet the drawing and the service conditions. The right finish improves corrosion resistance, fatigue life, and how well coatings stick. See this reference.
Casting Surface Roughness Ra
Casting surface roughness Ra measures how smooth a surface is. Investment casting gives a fine casting surface roughness Ra of about 1.6 to 3.2 micrometres as-cast, far smoother than sand casting.
Finishing options by smoothness:
- As-cast investment casting: about Ra 1.6 to 3.2 micrometres.
- Shot blasting: cleans and evens the surface.
- Tumbling: smooths edges and small parts.
- Machining: a precise finish on critical faces.
- Polishing and electropolishing: the finest finishes.
Shot Blasting Castings
Shot blasting castings is the first finishing step for most parts. Shot blasting castings removes ceramic shell residue, cleans and textures the surface, and prepares parts for machining or coating. It is a fast, reliable way to bring every casting to a consistent starting finish.
What shot blasting does:
- Removes ceramic shell residue after casting.
- Cleans and uniformly textures the surface.
- Prepares parts for coating or painting.
- Uses steel, ceramic, or glass-bead media.
- Can improve fatigue by inducing compressive stress.
Anodizing Aluminium Castings
Anodizing aluminium castings grows a hard, corrosion-resistant oxide layer. Anodizing aluminium castings such as A356 adds wear and corrosion resistance, though high-silicon alloys give a darker finish. For the best results, the alloy and anodize type are matched to the part’s duty.
- Grows a hard, corrosion-resistant oxide layer.
- Sulphuric and hard-anodize options.
- Best on lower-silicon aluminium alloys.
- Adds wear and corrosion resistance to A356 parts.
Why Choose Uni Tritech for Surface Finishing
Uni Tritech is a NADCAP-certified, AS9100D foundry approved by Airbus and Collins Aerospace. Our near-net-shape castings need minimal finishing, and we control every step with in-house NDT and laboratory services.
- Near-net-shape castings needing minimal finishing.
- In-house and qualified finishing partners.
- NADCAP-accredited NDT and laboratory services.
- AS9100D quality, Airbus and Collins approved.
Frequently Asked Questions
Investment casting achieves a casting surface roughness Ra of about 1.6 to 3.2 micrometres as-cast, far smoother than sand casting. Secondary finishing such as polishing can make it finer still.
Improve a cast part’s finish by shot blasting to clean and even the surface, tumbling small parts, machining critical faces, and polishing or electropolishing where the smoothest finish is needed.
Surface finishing aerospace castings covers every step after pouring that improves the surface, from removing shell residue to machining and coating, chosen to meet the drawing and service conditions.
Casting surface roughness Ra is a measure of surface smoothness. Investment casting gives about Ra 1.6 to 3.2 micrometres as-cast, which can be reduced further by finishing.
Yes. Anodizing aluminium castings grows a hard, corrosion-resistant oxide layer that adds wear and corrosion resistance. High-silicon alloys such as A356 anodize to a darker, still protective finish.
Need surface finishing on your aerospace castings? Contact Uni Tritech to discuss your components.
Need aerospace castings with a precise surface finish?
Uni Tritech delivers near-net-shape castings with controlled surface finishing. Talk to us about your parts today.
