Which colour gives the strongest parts?

K8200 3D Printer K8200 - Issues while printing
1

Hi Everyone.

I’ve been using the Velleman black PLA for some time and have been quite impressed by it’s flexibility and strength. I need to make some high strength parts and bought a spool of natural PLA in the assumption that the black dye would make it weaker, but discovered that the opposite is true. Natural is nowhere near as flexible or strong as black.

So as in the topic, my question is what colour gives the strongest parts?

2

Hi steve_b,

I’d say “Nylon”, but since that’s no color it probably wasn’t the answer you were looking for …

As for PLA, I could provide values for three colors: white, yellow, and blue, all from Velleman.

Cheers,
kuraasu

3

I’m making a small gearbox so I need good shear strength. If you have any technical data for the different colours it would be helpful to me. I had hoped Velleman would respond.

4

Hi steve_b,

here are the results:

White PLA: TS 55 - 57 MPa, YM 4.45 GPa
Yellow PLA: TS 56 - 57 MPa, YM 4.59 GPa
Blue PLA: TS 60 - 61 MPa, YM 5.14 GPa

TS is the tensile strength, i.e. the stress at the maximum of the stress-strain-curve,
YM is the Young’s modulus, i.e. the slope of the curve in the elastic region.

The curves shown above are examples. As you can see from the numbers, white has more variance than yellow and blue, but in the averaged values, the difference between white and yellow is small. Blue parts are a bit stronger than white/yellow, but yellow breaks later. However, the elastic region (left of the maximum) is pretty similar for all three colors.


This is how it actually looks like. You can see at the blue sample that there is a bit of stress whitening around the break.

Four of those samples (derived from an industry sample design, elongated slightly to better fit our machine) were printed with same settings. Actually, I would have changed the temperature if needed, but 190 °C was fine for all three colors. Three perimeters at 0.5 mm extrusion width (first and top layer: 0.4 mm) and full infill (1.0) in rectlinear pattern were used as parameters.

The set of four samples requires about 1 m of filament, so if anyone is interested …

Cheers,
kuraasu

5

That’s really useful, thanks. It confirms my suspicion that the dye used makes a difference. Any plans to test other colours?