China's Space Program News Thread

[taxiya]

3D printing is just a fancy technology . They do not offer the accuracy of the level that CNC machines can offer. Wire edm alone is 100 times more accurate that 3d printing. No need to talk about diamond turning.

Let's not jump from one extreme to the other by pitting 3D printing with CNC in a CNC favourable game. No technology is omnipotent, neither 3D printing nor CNC machines.

A counter argument would be this rocket engine turbine assembly. No matter how many axis a CNC machine may have or how accurate it's arm may move, it is impossible to make these weird shaped component without welding. 3D printing save the time, so save the money.


13 units out of 16 of this turbine assembly are made by 3D printing. That is 85% of its mass being printed. It also reduced its size by 40% compared to traditional fabrication method.

The engine (using the turbine assembly above): Core parts reduced from 25 to 3. Eliminating 200 welding (if done traditionally), that is removing 200 potential defects.

The engine has been tested, and probably flown.

 

[sferrin]

If it hasn't been posted already. (Just to show what is possible

 

[PeoplesPoster]

CNC or sheet metal forming is best for mid sized production runs in the hundreds for mid sized components (~meter sized).

Materials costs for most rocket components aren't that high, it's just aluminum and stainless. Processing costs are far higher. 3D printing isn't good because of material waste for general materials, because you have to powder the material first which is even more wasteful while for CNC and sheet metal techniques you start with a block or a sheet which is how the parts come out straight from the refinery.

That's why I point out that small critical components with weird shapes or that are refractory and thus need to be powder formed anyways are the best 3D printing candidates.

No its the opposite. Most powdered metals are produced for much higher volume applications like powder coating or can be produced relatively easily with newer gas atomization processes. It's true that you won't have as low per kg cost as a single block of material, but at the same time you won't need to use as much. In 3d printing any powder not used on the part can typically be recycled and reused. CNC you start with a block and everything that's that is cut off from the block is trashed.

 

[PeoplesPoster]

3D printing is just a fancy technology . They do not offer the accuracy of the level that CNC machines can offer. Wire edm alone is 100 times more accurate that 3d printing. No need to talk about diamond turning.

Wrong approach to the technology. While true that current 3d printing dimensional accuracy cannot match CNC, the key to 3d printing is complex geometries and internal channels which CNC or Wire EDM just cannot do. If you require CNC accuracy with a 3d printed part, what you can do is add enough stock material onto the 3d printed part then do a final pass with a CNC, achieving both accuracy and complexity.

3d printing and CNC are just tools, they don't replace each other. Every competent manufacturer or machine shop should be able to use both to achieve their desired results.

 

[sferrin]

No its the opposite. Most powdered metals are produced for much higher volume applications like powder coating or can be produced relatively easily with newer gas atomization processes. It's true that you won't have as low per kg cost as a single block of material, but at the same time you won't need to use as much. In 3d printing any powder not used on the part can typically be recycled and reused. CNC you start with a block and everything that's that is cut off from the block is trashed.

Start with a 200kg forging, for example, and end up with a 12kg part and a mountain of chips.

 

[FairAndUnbiased]

No its the opposite. Most powdered metals are produced for much higher volume applications like powder coating or can be produced relatively easily with newer gas atomization processes. It's true that you won't have as low per kg cost as a single block of material, but at the same time you won't need to use as much. In 3d printing any powder not used on the part can typically be recycled and reused. CNC you start with a block and everything that's that is cut off from the block is trashed.

What's about the throughput? The natural porosity for laser sintered parts? What's the cost savings of material (especially for stainless or aluminum) vs the cost of lower throughput or needing structurally thicker parts to compensate for the mechanical weakness?

If 3D printing is the be all end all how come most high quality stainless and aluminum metal parts are still done in CNC or with sheet metal techniques, while 3D printing is mostly done for titanium, refractory metals and other materials that are either expensive or hard to manage with CNC, or used for weird, small shapes?

 

[siegecrossbow]

What's about the throughput? The natural porosity for laser sintered parts? What's the cost savings of material (especially for stainless or aluminum) vs the cost of lower throughput or needing structurally thicker parts to compensate for the mechanical weakness?

If 3D printing is the be all end all how come most high quality stainless and aluminum metal parts are still done in CNC or with sheet metal techniques, while 3D printing is mostly done for titanium, refractory metals and other materials that are either expensive or hard to manage with CNC, or used for weird, small shapes?

Titanium is a lot more expensive to process than aluminum/stainless steel. From what I've heard the metal shavings left over can't easily be reused unlike aluminum. Using 3D printing is actually worth the cost.

 

[sferrin]

What's about the throughput? The natural porosity for laser sintered parts? What's the cost savings of material (especially for stainless or aluminum) vs the cost of lower throughput or needing structurally thicker parts to compensate for the mechanical weakness?

If 3D printing is the be all end all how come most high quality stainless and aluminum metal parts are still done in CNC or with sheet metal techniques, while 3D printing is mostly done for titanium, refractory metals and other materials that are either expensive or hard to manage with CNC, or used for weird, small shapes?

As others have mentioned, 3D printing is just another tool. You have to weigh everything. Material costs, part weight, part count, part geometry, time to manufacture, scrap, NRE; all go into the calculation. A CNC part, made from a titanium forging, might be the lightest way to go but if it's got a lead time measured in months or years, and you need multiple pieces because of geometry, and you can print a part that is "good enough" all things considered, then the printed part will win out.

 

[FairAndUnbiased]

Titanium is a lot more expensive to process than aluminum/stainless steel. From what I've heard the metal shavings left over can't easily be reused unlike aluminum. Using 3D printing is actually worth the cost.

Yes I mentioned titanium as a good 3D printing candidate.

As others have mentioned, 3D printing is just another tool. You have to weigh everything. Material costs, part weight, part count, part geometry, time to manufacture, scrap, NRE; all go into the calculation. A CNC part, made from a titanium forging, might be the lightest way to go but if it's got a lead time measured in months or years, and you need multiple pieces because of geometry, and you can print a part that is "good enough" all things considered, then the printed part will win out.

See above. Titanium is a good 3D printing candidate. Stainless and aluminum aren't. My original post was about how 3D printing wasn't the be all end all to replace CNC and sheet metal.

 

[sferrin]

Yes I mentioned titanium as a good 3D printing candidate.


See above. Titanium is a good 3D printing candidate. Stainless and aluminum aren't. My original post was about how 3D printing wasn't the be all end all to replace CNC and sheet metal.

Depends. That rocket company in the video I posted above is printing the entire airframe out of a proprietary aluminum alloy.