One seat fitting. Every way to make it.
The pivot fitting that carries an aircraft seat's backrest, designed from one set of requirements for six manufacturing processes and four alloy families at once, then checked for strength, stiffness, ductility, mass and cost.
- mass: 725 g today, 279 g recommended
- −62 %
- configurations considered, 19 designed and verified
- 24
- meet every requirement
- 5
- per part at 2,000 a year, recommended design
- $59
A study we ran on a representative part, not a client project: the interfaces and loads follow a typical certified economy seat; the cost figures come from simple, stated models.
What the part has to do.
Two M8 bolts to the seat's side plate, a Ø12 backrest pivot, a Ø8 lug for the recline lock, and a keep-out zone for the tray-table mechanism. Inside a 120 × 180 mm envelope, everything else is free.
| Load case | Force on the pivot | Checked against |
|---|---|---|
| Backrest recline | 12 kN, cyclic | fatigue, safety factor 1.25 |
| 16 g forward crash | 28 kN | yield, safety factor 1.5 |
| Downward push | 9 kN | yield, safety factor 1.5 |
- Stiffnesspivot deflection ≤ 1 mm
- Ductilityelongation at break ≥ 5 % (crash)
- Mass≤ 400 g (today: 725 g)
- Cost≤ $250 per part at 2,000 a year
Twenty-four designs, not one.
- 01Rule outCombinations with no production route are dropped before any computing: magnesium is not printed, investment cast or bent as sheet in production; titanium and steel are not die cast.
- 02DesignFor every remaining process and alloy, topology optimisation finds where material carries the three load cases, with the volume and the weight of each case tuned to that alloy's strength.
- 03Make it makeableEach result is reshaped by its process: tool radius for milling, draft and fillets for casting and forging, constant thickness and bends for sheet, the thinnest printable members for powder-bed printing.
- 04VerifyThe final shapes are checked again with finite elements: fatigue and yield with safety factors, pivot deflection, ductility, then mass and cost.
- 05RankQualified designs are ranked by price plus the value of mass over the aircraft's life ($2,700 per kg).
Process × material.
| Material ↓ / Process → | CNC milling | Metal 3D printing (LPBF) | Investment casting | Laser-cut and bent sheet | Closed-die forging | High-pressure die casting |
|---|---|---|---|---|---|---|
| Aluminum | Al 7075-T7351279 g · $59Recommended | Scalmalloy242 g · $258Fails: cost | A357-T6370 g · $51Qualified | Al 2024-T3 sheet261 g · $21Fails: strength | Al 7075-T73 forging326 g · $52Qualified | Al A380 die cast412 g · $27Fails: strength, ductility, mass |
| Titanium | Ti-6Al-4V251 g · $307Fails: cost | Ti-6Al-4V (HIP)259 g · $340Fails: cost | Ti-6Al-4V (cast, HIP)266 g · $174Qualified | Ti grade 4 sheet420 g · $44Fails: strength, mass | Ti-6Al-4V forging379 g · $145Qualified | No production route |
| Steel | AISI 4130 Q&T525 g · $116Fails: mass | 17-4PH H900395 g · $272Fails: cost | 17-4PH (cast, H1025)458 g · $65Fails: mass | 301 stainless ½ hard492 g · $25Fails: mass | AISI 4340 forging656 g · $57Fails: mass | No production route |
| Magnesium | Mg Elektron 43476 g · $66Fails: mass | No production route | No production route | No production route | Mg Elektron 43 forging454 g · $70Fails: mass | Mg AM60B die cast275 g · $28Fails: strength |
Mass of the finished part and price per part at 2,000 a year. Most of the fourteen failures are not strength but mass: steel and magnesium designs that hold the loads end up over the 400 g limit. Milled titanium and every printed design pass the engineering checks and fail on price; bent sheet and die casting fail on strength.
Milled aluminum.
Al 7075-T7351, machined from plate: 279 g instead of 725 g, $59 a part, the lowest price plus lifetime value of the five that pass.
| # | Configuration | Mass | Price | Price + mass value |
|---|---|---|---|---|
| 1 | CNC milling, Al 7075-T7351 | 279 g | $59 | $812 |
| 2 | Investment casting, Ti-6Al-4V (cast, HIP) | 266 g | $174 | $891 |
| 3 | Closed-die forging, Al 7075-T73 forging | 326 g | $52 | $932 |
| 4 | Investment casting, A357-T6 | 370 g | $51 | $1,051 |
| 5 | Closed-die forging, Ti-6Al-4V forging | 379 g | $145 | $1,168 |
A first answer in hours.
The whole design space, 24 configurations, ran in about two and a half hours of compute. It is a planar model with stated cost models: the right tool to decide which two or three directions deserve full 3D analysis, supplier quotes and a test article, not a replacement for them.
We are now running it in pilot projects with engineering teams, on their own parts, with their loads, standards and suppliers. If one of yours costs you weeks, we would like to run it.
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