Why do aircraft parts have to be polished by hand?

For the production of modern aircraft, many people believe that the production speed of aircraft should be very fast in modern production plants and modern automated production lines.

In fact, the production speed of the aircraft is not as fast as we thought, and the current aircraft production is still inseparable from manual grinding. Take domestic-made JH-7A, H-6K and Yun-20 as examples to see the manual polishing process.

CCTV's National Defense Military Channel "Defense Science and Technology" reported a person who "talked" with a hammer and a fighter. His name was Li Shifeng. He was a member of the aviation industry's Xifei sheet metal industry. Hammer, knock out hundreds of fighters.

Most of the components of the JH-7A, H-6K and Yun-20 (which can account for 40% -70% of the entire fuselage of the aircraft) are machined and hand-trimmed. Because of the special shape of aircraft parts and the small number of varieties, many are unique customized models. Due to the small number of special machine tools, it is an internationally popular way to manually create aircraft sheet metal parts.

Where is the difficulty of manual polishing?

The materials used in the fuselage of modern fighters are very special. The raw materials are soft materials when they enter the factory. After the initial shaping, they must undergo a high-temperature treatment of 500 degrees Celsius and a normal temperature treatment of 30 degrees Celsius to make the metal strength meet the equipment requirements. Hot and cold will cause irregular distortion of the metal plate, and the thinner the material is, the stronger the deformation will be, and then the adjustment work needs to be restored.

After tens of thousands of percussion throughout the day, the previous uneven metal plate was evenly flat like a piece of thin paper.

The precision of the gap is high, and no hair can pass through

The thinnest board that can be used in the fighter fuselage structure is only 0.5 mm thick. It is installed at the junction of the fuselage and the tail. To achieve a perfect fit with the fuselage, the gap accuracy cannot exceed 0.02 mm. One hair thread is worn But go.

Why do you need such demanding clearance accuracy? Because there is a gap, it will not seal, and it may tear from that part. You know, disintegrating in the air and tearing the skin is as easy as tearing a piece of paper.

So, is it really a sign of backward technology and insufficient production capacity to manually polish aircraft parts?

The answer is of course no. Manual processing of aircraft parts is not a reflection of backward technology. On the contrary, although today's industrial technology has been highly automated, due to technical constraints, the manufacture and polishing of some parts cannot be completed using automated machine tools. Completed by manual processing!

Moreover, manual polishing is not the only way for our country to do this. As mentioned before, this is an internationally accepted method.

In Boeing ’s factory in Seattle, there is a group of 20 workers, who are responsible for polishing the skin of the aircraft. Their work is exactly the same as Li Shifeng introduced in "National Defense Science and Technology". Polished airplane skin by hand. In today's world, all kinds of large-scale civil aviation aircraft, such as Boeing 737, 757, 767, and 777, are hammered out of a hammer in a factory in Seattle.

The European Airbus plant in Toulouse and the British Rolls-Royce plant in Derby also have workers holding hammers and chisels, which are responsible for polishing the skin of the aircraft. Because the skin of the aircraft is irregularly curved and very thin, defects will appear if you don't pay attention. There is no way to use the machine tool to process it, and it can only be knocked out by manpower.

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