Chinese Aviation Industry

Ultra

Junior Member
Aluminum alloy milling speeds have reached 1,000 meters (3,300 ft. per min. and material removal 25-30 kg (55-66 lb.) per hr. Large aircraft parts 1.5-2 mm thick are being precisely milled on both sides. For titanium, the milling speed has reached 60-80 meters per min.

Question - why are they using 2 different measurement? Aluminium alloy are being milled at 1000 meters per hour, while titanium are being milled at 60-80 meters per minute? If you do the math that means they are faster at milling the titanium by a factor of almost 5 !! (80x60 = 4800 meters)

Why I raise this question is because I thought Titanium is a much harder material to work with.
 

schenkus

Junior Member
Registered Member
Question - why are they using 2 different measurement? Aluminium alloy are being milled at 1000 meters per hour, while titanium are being milled at 60-80 meters per minute? If you do the math that means they are faster at milling the titanium by a factor of almost 5 !! (80x60 = 4800 meters)

Why I raise this question is because I thought Titanium is a much harder material to work with.

I think it meant "1000meters (3300ft) per minute", so it is 12times faster than titanium. Only the material removed is given in values per hour.
 

nemo

Junior Member
Question - why are they using 2 different measurement? Aluminium alloy are being milled at 1000 meters per hour, while titanium are being milled at 60-80 meters per minute? If you do the math that means they are faster at milling the titanium by a factor of almost 5 !! (80x60 = 4800 meters)

Why I raise this question is because I thought Titanium is a much harder material to work with.

Not sure whether that's an typo or not, but it's actually harder to machine soft metal than hard metal due to deformation during metal work -- you have to slow it down and use sharp blade to limit force on the material. Also heat during machining may be a problem -- one of the technique used to limit that is to dump the aluminum part in liquid nitrogen to limit warping due to heat generated by friction during machining (BTW, don't try it on any other metal -- dumping it in liquid nitrogen can cause explosion.)
 

SamuraiBlue

Captain
I think it meant "1000meters (3300ft) per minute", so it is 12times faster than titanium. Only the material removed is given in values per hour.

Very unlikely more like 60~80 meter per hour for Titanium.
1,000 meter per minute is 60 Km/h. No way can you do any precision milling at that speed.
 

I wonder

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By:
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SINGAPORE
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16 hours ago
Final assembly work on the
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has kicked into high gear, with assembly of the first prototype airframe almost complete.

Pictures released to Flightglobal show an almost complete airframe joined from nose through to the tail. Wing-to-body join has also been done, with the vertical and horizontal stabilisers already attached to the aircraft's tail.

The aircraft is still resting on struts, although the main landing gear and forward landing gear appear to have been installed. The aircraft's wingtip devices have also yet to be installed. No other aircraft are pictured in the final assembly centre area.

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Comac

A Comac spokesman tells Flightglobal that no systems have been installed on the aircraft.

Over the last six months the Chinese aircraft manufacturer has been taking delivery of the jet's major structures, with final assembly work officially started last September.

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Comac

Comac has publicly stated end-2015 as the aircraft's first flight target, and the spokesman says the goal remains to strive towards that timeline.

He adds however that major works such as the installation of the avionics, flight control and hydraulics systems still remain to be done. The various systems also have to be integrated and tested.

Tests are however ongoing at full-swing on the C919 iron bird test rig, with more than 50 test engineers and technicians involved.

An official on the indigenous Chinese programme told Flightglobal last September that the iron bird is scheduled to undergo two cycles of tests before the C919's first flight.

Delays on the aircraft's first flight are however expected since system integration will be complex for Comac, another official says.

Comac has so far secured 450 commitments for the in-development narrowbody from 18 companies, most of which are local airlines and leasing firms.
 

asif iqbal

Lieutenant General
Now THAT is a very modern looking aircraft and I believe a Chinese success story once everything is done

However personally speaking I do not think it will fly by end of 2015 there is still a lot of work to do on this aircraft before it can fly

I would say around mid 2016 for flight if all goes well
 

I wonder

New Member
Registered Member
The Following post is from August 2014 but I thought it was interesting in that it said that Al-Li was being used.

Fwd fuselage section of first C919 aircraft delivered in Shanghai


Last Updated (Beijing Time):2014-08-24 Source:News Center of COMAC
Color vision protection:

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Fwd fuselage section of first C919 aircraft was delivered at Pudong base of COMAC Manufacturing and Final Assembly Center on August 24th, 2014. This is the first section delivered during the development of C919 program and has great significance for further accelerating the development of C919 aircraft.

The fwd fuselage section of C919 aircraft had rolled out successfully in the large component assembly workshop of AVIC Jiangxi Hongdu Aviation Industry Group Corporation Limited on May 15th, 2014. The fwd fuselage section uses third-generation Al-Li alloy for the first time in civil aircraft application, which is favorable for improving the performance of aircraft structural material and reducing the weight of the whole aircraft structure.
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This following post mentions Li-Al in relation to the 777X and shows it would be a significant
improvement over plain Aluminium.

Aluminum-lithium alloys may be used for Boeing 777X
May 3, 2013, 2:44pm PD
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Staff Writer-Puget Sound Business Journal
As Boeing officially enters the fray against
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in the large twin-jet category with Boeing's planned 777X, a secondary theme is that Boeing is continuing to bet on aluminum.

But not your parents’ aluminum.

The stretched 777-9, the biggest twin-engine model Boeing Co. (NYSE: BA) is planning to build, may be partly fabricated from a new breed of aluminum-lithium alloys, lighter and stronger than the aerospace-grade aluminum now used. Boeing
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Yes, these new alloys do include lithium, the highly reactive metal that caused Boeing such problems with the 787’s lithium-ion batteries. (Boeing’s 787 Dreamliner has been grounded for more than three months due to charring of two lithium-ion batteries, and only recently was cleared to return to service by the Federal Aviation Administration, after an expensive battery fix.)

But don’t worry, when lithium and aluminum are mixed together, the resulting alloy has no propensity to combust.

The promise of aluminum lithium alloys is so interesting to the aerospace industry that an entire panel was devoted to the subject at the Pacific Northwest Aerospace Alliance annual conference in Lynnwood, in February.

Executives from Dutch aluminum company Constellium and from
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Aerospace updated the audience, mostly made up of aerospace suppliers.

“As aircraft design requirements change, aluminum is still innovating, and we expect to be here for a long time,”
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, an Alcoa engineer, told the crowd. “New aluminum lithium alloys can offer 1 to 2 percent improvements for long-range aircraft.”

Alcoa is
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to produce aluminum lithium alloys, expecting it to be incorporated in new aircraft including Boeing’s planned 777 and perhaps the 737 Max. Boeing hasn't said whether or not it will use aluminum-lithium alloys in either plane.

Alcoa is now building a $90 million aluminum-lithium ion production plant in Lafayette, Ind. When completed next year, the new factory will be able to produce 200,000 metric tons of the alloy a year.

“Our primary role as aerospace solution providers is to help the OEMs (original equipment manufacturers) reduce fuel consumption per seat mile,” said
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, president of Alcoa Forgings and Extrusions, in a statement at the factory groundbreaking last year. “Our aluminum-lithium supply chain will be the premier operation in the world, and this specialty alloy will be flying on the next generation of aircraft.”

Alcoa also is expanding another aluminum lithium facility, located in Upper Burrell, Penn.

Currently Boeing’s popular 777 300-ER weighs 370,000 pounds when empty, and carries 386 passengers in a standard configuration. The new stretched 777-9 is intended to carry 21 more passengers. What if the combination of a aluminum-lithium fuselage and a new composites wing made its weight the same or less?

That might be a key to competing against the formidable Airbus A350-1000, which features a light composites fuselage and wings. Airbus engineers are claiming their plane, which also uses aluminum lithium alloys, will be 25 percent more fuel efficient, on a per-seat mile basis, than the current 777. And a big piece of that gain is about less weight.

Alcoa claims that using its aluminum-lithium alloys can lower an aircraft’s weight by 10 percent, and manufacturing and repair costs by 30 percent.

These are big numbers. It’s very likely you’ll hear word lithium used a lot around the 777-9, and the word won’t be referring to batteries.


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I wonder

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This is mostly a rehash of the earlier flightglobal article but includes an interesting paragraph on the materials being used compared to the a320 and 737.

On its website, COMAC has stated, “While we need to catch up to the 787 and A380 in material technology, the C919 has a competitive advantage over the Airbus A320 and Boeing 737. Titanium alloy is 10% of the C919's structural weight, compared with 2.2% in the 737 and 4.5% in the A320. At present, the proportion of composites used in the C919 is higher than that for the 737 but a little lower than for the A320. The C919 also includes an aluminium-lithium alloy.”

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