# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/DdbjVbhgACg
- **Gondola URL:** https://gondola.cc/posts/70577835-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/a39fb707f7.jpg
- **Posted:** 2026-09-18T13:34:24.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

Every F-35 in service traces back to one building on Harvard Avenue in Cleveland, Ohio. The aircraft is not assembled around a welded frame. It is built around a spine of enormous aluminium die forgings, and all of the large ones come off one shop floor.

Under the 2007 Lockheed Martin award to Alcoa, now Howmet Aerospace, each airframe receives fifteen large bulkhead forgings and six wing box components. The bulkheads carry wing and engine loads, run from 10 to 23 feet in length, and weigh between 1,800 and 6,000 pounds as forged, before machining strips most of it away.

The machine that makes them is a Cold War survivor. Built by Mesta Machinery of West Homestead, Pennsylvania under the Air Force Heavy Press Program, the 50,000-ton press entered service on 5 May 1955.

- 87 feet tall, with roughly half the structure buried below the shop floor
- A frame weighing close to 8,000 tons
- Eight rams at 4,500 psi hydraulic pressure across a six-foot stroke
- A die table measuring 26 by 12 feet

Forging instead of machining from plate is a metallurgical decision, not a convenience. Closed-die forging bends the wrought grain structure to follow the contour of the part, so flow lines run along the load paths instead of being severed by a cutter. One pressed bulkhead replaces a built-up assembly and deletes hundreds of fastener holes, and every hole removed is a crack that never initiates.

The alloy matters as much as the press. Alcoa introduced 7085 in 2003, an Al-Zn-Mg-Cu composition with a higher zinc to magnesium ratio and lower copper than 7050. Its low quench sensitivity holds strength and toughness uniform through sections up to 12 inches thick, where older 7xxx alloys go soft in the middle.

Cracks in the press base castings idled it in 2008. A 100 million dollar rebuild returned it to work in February 2012.

Some industrial capability cannot be replaced, only maintained.

#stemantics #materialsscience #aerospaceengineering #metallurgy #manufacturing

## Stats

- **Views:** 4,774
- **Likes:** 61
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- **Comments:** 2

## Tags

materialsscience, manufacturing, aerospaceengineering, stemantics, metallurgy

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