3D printing promises to revolutionise the manufacturing industry, according to
some. However it has certain practical obstacles to overcome.
For instance, it is tricky to construct an assembly consisting of multiple
unconnected parts which must be free to move with respect to each other;
3D printing
and casting both struggle with this, for closely related reasons.
Here's a hybrid scheme which may be able to produce assemblies which
other
methods cannot.
Step 1:
A robotic print head lays down material in a grid of voxels.
Each voxel contains a mixture of different materials. Most importantly, it either
contains, or does not contain, a material which melts at or below the target
firing
temperature, to be reached in stage 2. Equally importantly, every voxel must
contain _something_; it is not acceptable for the voxels overhead to be left
unsupported at any stage. The 'scaffolding' material will be removed in step 3.
The result of this stage is basically a lump of slightly damp sand, albeit sand
with
considerable invisible internal structure.
Step 2:
The lump is fired in a kiln. The sinterable regions within fuse into the desired
target material. The non-sinterable regions do not sinter, as the astute reader
may have already guessed.
Step 3:
The non-sinterable material is removed. For simple parts this might just
consist
of spraying them with water; for more complex parts it may be worth choosing
a
solvent which can dissolve it, and arranging for internal channels so that the
solvent can be pumped through the interior.