MATERIAL STUDY

3D printed prosthesis

PRINTING PROcESs

2017-2018 (MAKERBOT REPLICATOR 5th GEN)

Creating the cylinders

*When reading through my website, please note that the plastics I ended up selecting will be shown against a red backing

the Diamond Clamp:

The Diamond Clamp (DC) was created to start testing plastics. I am trying to do both a sustained pressure testing and a blunt force impact test. This contraption featured below I created by hand in order to test plastics over a long term. By hanging a weight in front and clamping the top over a hollow 3D printed cylinder that will be left there in long durations I hope to test and record the strength and durability of each plastic.

Side view of testing apparatus

Front view of testing apparatus

Open view

HIPS

PRINTED USING: PRUSA MK3

In DC front

In DC side

FLEX

PRINTED USING: PRUSA MK3

In DC front

In DC side

ABS

PRINTED USING: PRUSA MK3

In DC front

In DC side

POLY-CARBONATE

PRINTED USING: PRUSA MK3

In DC front

In DC side

NYLON

PRINTED USING: PRUSA MK3

In DC front

In DC side

the testing process

CHECK-IN: SLOW COMPRESSION

SET UP: SLOW COMPRESSION

Without weights

With weights

1 kg weight

stabilization (to avoid tipping)

weighted diamond clamp

CHECK-IN

12/9/19

Measurements:

TOP TO BOTTOMOriginal diameter 3 in

ABS

Diameter: 3 in

HIPS

Diameter: 3 in

NYLON

Diameter: 3.78 in

CARBON

Diameter: 3 in

FLEX

Diameter: 2.55 in

SLOW COMPRESSION

#1: 12 - 11 - 2019

TOP ROW: DIAMETER MEASUREMENTS AFTER 2 WEEKS

BOTTOM ROW: FRESH PRINTED CYLINDERS WITHOUT TESTING

RESULTS: FLEX: 2.55 in NYLON: 2.78 in ABS: 3 in CARBON: 3 in HIPS: 3 in

(BLACK) (WHITE) (WHITE) (BLACK) (BLUE)

*LEFT TO RIGHT, Original diameter 3 in; measurements above in direction of compression

#2: 1 - 9 - 2020

TOP ROW: DIAMETER MEASUREMENTS AFTER 6 WEEKS

BOTTOM ROW: FRESH PRINTED CYLINDERS WITHOUT TESTING

FLEX: 2.50 in NYLON: 2.75 in ABS: 3 in CARBON: 3 in HIPS: 3 in

(BLACK) (WHITE) (WHITE) (BLACK) (BLUE)

*LEFT TO RIGHT, Original diameter 3 in; measurements above in direction of compression

FAST COMPRESSION: 1 / 9 / 2020

CHECK-IN

What do these results mean?

By looking at the breaking of the plastics at a micro view, I have concluded that Nylon, FLEX, and Carbon would be the best materials to print my prosthesis. The Carbon was the most sturdy (holding its form) with the most pressure, this plastic I would like to use for the palm and wrist. I have selected Nylon for the finger sections; I decided to use this material because it holds its form, but also has a flexible component that would benefit the flange movement. I would also like to use FLEX in between the finger joints to bridge the pieces, because it doesn't entirely hold form, allowing for larger range of motion. (RESULTS SEEN BELOW)

HIPS:

START WIDTH: 3 in FIRST STRESS MARKS: 2.5 in BREAK 1.9 in

In the photo above you can see that were many stress lines, starting on the sides in a perpendicular fashion. These stress lines turned white, evidence of microscopic cracks, appearing on the inside, as the inner printed cylinder was compressed only 0.5 in.

As seen in the photo, there was no top break, but high amounts of strain. From this data, I can tell this plastic, although rigid, can distribute pressure in a more balanced way. There was a smaller break on the left side of the cylinder, which shows that this plastic is not fully flexible even though it does hold more forgiving properties in terms of pressure distribution.

NYLON:

START WIDTH: 3 in FIRST STRESS MARKS: N/A BREAK: N/A

In the photo above you can see that were are no visable stress-lines (which would have been harder to see since the plastic was white.) The filament was very flexible and there was no audible cracking sound.

As seen in the photo, there was no break after full clamp pressure was exerted. This data showed me that this plastic was malleable, but also retained shape, which is a useful trait.

ABS:

START WIDTH: 3 in FIRST STRESS MARKS: 2.2 in BREAK: 1.9 in

The stress lines were not as visible since they appear unusually in a whitening of the surface. These first stress lines were determined when I heard a click. The amount of distance moved wasn't that much (0.8in) before the first click; this immediately informed me that this plastic was rigid and slightly weak.

As seen in the photo, there was a break once the clamp closed to 1.9in. This break formed in two places, the top where the right came over the left, and the middle of the left side of the arc. The top completely detached, showing the pressure was not equally distributed; this makes the plastic more variable.

CARBON:

START WIDTH: 3 in FIRST STRESS MARKS: 2.5 in BREAK: 1.75 in

The photo above shows carbon after the first crack (2.5in), the strain was not visible, but I could tell immediately that this material was very rigid in its form.

The break was very sudden; the inner cylinder seemed to become detached from the outer cylinder. The two layers seemed to act more independently of one another and became a little more flexible after that. Although the break was sudden, the plastic held its form, which would be a beneficial trait.

FLEX

I DECIDED NOT TO TEST BECAUSE IT WAS FLATTENED BY THE SLOW COMPRESSION

BREAKS UNDER THE MICROSCOPE:

1 / 13 / 20

HIPS

HIPS has a partially successful bond when it prints; this means that during the break, the sections didn't totally come apart, but it also broke in a staircase-like fashion showing that the print didn't act like one piece.

40x

100x

400x

ABS

ABS has a looser print according to the microscopic look at the breaks (showing breaks both along and between strands). This makes the plastic weaker, and since it didn't have any flexible attributes to it, ABS is not an ideal material to use.

40x

100x

400x (too thick)

CARBON

In this microscopic view I can see that the carbon has very tight bonds when printed and that makes it alot stronger. This trait makes Carbon an ideal material for the palm of the hand.

40x

100x

400x (too thick)

FLEX

NO BREAK

NYLON

NO BREAK

Practice

FRACTOGRAPHY UNDER THE MICROSCOPE: 10/26/19

Looking into fractography, the study of breaking materials, will help me futher understand the properties of 3D printed mattterials. This will help me determine which materials would work best for my 3D printed prosthesis.