Multimedia

Process Video

Bronze Packing Process

Bronze Packing Process.mov

Steel Packing Process

Steel Packing Video.mov

Bronze_Dogbone_Timelapse.MOV

Print Time Lapse

Time lapse of bronze dogbone printing.

Printed Parts

Sample testing performance of different thicknesses.

Bronze disk sample

Bronze fatigue sample

Early steel cube sample

Later steel cube sample

Steel gear sample

Early bronze cube, lump from lack of compression

Early bronze cube

Later bronze cube

Later bronze dogbone

Compression Mechanism

Performance

Starting from left: Standard PLA benchy, uncompressed bronze benchy, bronze benchy compressed with mechanism, uncompressed stainless steel 316L benchy, stainless steel 316L benchy compressed with mechanism. Compressed benchies show improved geometric retention and reduced shrinkage compared to uncompressed.

Final Design

Images of our compression mechanism prototype and actual mechanism.

Compression Mechanism Prototype

Prototype made from laser cut acrylic

Final Assembled Compression Mechanism

Actual mechanism made entirely from machineable alumina

CAD Images

Images of CAD models of our 4 proposed compression mechanism designs.

Design 1: Alumina Bolt

Design 2: Tungsten Flexures

Design 3: Tungsten Barbells

Design 4: Single Bolt Mechanism

Validation for Use of Compression

We used bricks to apply pressure to our parts to validate the necessity of our compression mechanism.

Brick is placed on kiln paper fitting in crucible to apply compression to refractory powder in crucible.

Side view of compressed dogbone (top) vs. uncompressed dogbone (bottom). Warping/bowing apparent on uncompressed dogbone

Debinded dogbone ran without compression. Can see pillowing and deformation in grip section.

Debinded dogbone ran with compression. No geometric deformeties apparent.

Alumina Laser Cutting

If we could use non-machineable alumina for our compression mechanism, it would greatly reduce the cost. Image on the left shows our failed attempt at laser cutting alumina. This was the depth achieved after an 1hr and a half. Alumina slab is about 5 mm thick.

Compression Testing

Images from our testing to determine the ideal range of compression to be exerted by our compression mechanism. We tried to find how much force it took to get diminishing amounts of change in powder height. This was found to be around 5 psi.

Uncompressed powder

Measuring Uncompressed Height

Pressing Powder to Compress and Measuring Applied Pressure

Measuring Compressed Height

Oxidation Testing

Images from our testing of oxidation of Tungsten to test its viability for use as a material in our compression mechanism. We ran one tungsten rod through a bronze debind cycle and one through a bronze sinter cycle.

Pretest vs. Post Debind Cycle Specimen

Post debind (left) specimen is visibly darker than pretest specimen (right) indicating oxidation.

Post Sinter Cycle Specimen

Specimen after being run through sintering ramped cycle only. 2.6% mass difference before and after run due to oxidation. Oxidation is vey visible in this image.

Sintering Specimen at 250 Celsius

Inside of tube furnace with sintering specimen placed inside an alumina crucible at 250 C.

Sintering Specimen at 885 Celsuis

Inside of tube furnace with sintering specimen at 885 C.

Microstructure Characterization

Image Processing

A MATLAB image processing script was written to take in images from a microscope of our samples and isolate the voids. Isolated voids were then used to get an estimate of porosity.

RGB image of Bronze sample under a microscope

Black and white image of sample. White sections are voids.

Voids isolated using a MATLAB image processing script. Color of voids correlates to their size (Rainbow color scale). Red = large, Blue = small.

Void Size Histogram

Spread of void size obtained from isolated voids using image above.

SEM elemental composition

Elemental composition of a steel sample obtained from a scanning electron microscope.

Material Property Characterization

Testing Samples

Cube samples were used to characterize shrinkage, density, and hardness. Disks were used for characterizing the microstructure. ASTM dogbones were used for tensile strength.

Steel Cube sample (green on top and post-sintered on bottom)

Bronze Disk Sample

(green on top and post-sintered on bottom)

Bronze Dogbone Sample

(green on top and post-sintered on bottom)

Characterization

Images and videos from our characterization of our samples

Tensile Testing of a Bronze Dogbone

Bronze Tensile Test.mov

Hardness test on Bronze specimen

Density

We measured the displacement of water before and after our specimens were place in it to get its volume (Archimedes Method). Then we divided its weight by the displaced volume to get its density.

Bronze Cube Specimen

Taking the weight

Volume of the water before displacement

Volume after displacement

Shrinkage

We measured our parts after each step green, brown, sintered, and post sintered. These measurements we used to keep track of how much parts shrink with each step.

"Green" benchy (left) vs. Post Sintered Benchy (right) showing amount of shrinkage after debinding and sintering.

Printing Modifications

Printer Enclosure

We built a printer enclosure to prevent warping of parts from exposure to cooler air while printing. It was built from 3D printed PLA parts, laser cut acrylic, and wood.

Printer Before

Printer With Enclosure

Front Page Photos

Four Benchies

Starting from the left: bronze benchy ran without compression, bronze benchy ran with compression mechanism, Stainless steel 316L benchy ran without compression, and Stainless steel 316L ran with compression mechanism.