Transcript:
When you prepare a model for 3D printing, you’’ll always need to choose an infill structure for your part. Since current slicers give you the option of choosing between a whole lot. You might have already been asking yourself. Which one is the strongest and most suitable for your application? So in today’s video, we’’ll crush some test samples to find out which performs the best and I was especially interested in the much hyped Gyroid infill you might have heard of. Guten Tag Everybody I’m Stefan. And welcome to CNC kitchen. In a previous video, I’ve already been taking a look at the strength of different infill structures that you can find in Simplify3D and also talked about why it is more efficient in many cases if you increase the number of perimeters instead of increasing the infill percentage. If you haven’’t seen it yet there is a link in the description. I wanted to do a bit more research in this direction and especially find out how different patterns behave in different directions Because often you can’t Orient your part in a way that it is perfect for the chosen infill. In addition, Slicer Prusa Edition features 3 3 dimensional infill structures most prominently gyroid infill that claim to have more isotropic so more uniform strength behavior in all loading directions. In order to perform the tests for this video, I had to adapt my tensile testing machine in order to be able to perform compression tests. If you are interested in the machining process on my CNC, there is also a link in the description to that video. I’’ve been thinking for quite a while. About a suitable test specimen. At first, I thought of just printing the infill pattern without any exterior walls, but since the infill in your parts will always be surrounded by a shell of material, which is reinforcing the structure. I ended up printing cubes of 22mm side length that use 1 perimeter and 3 top and bottom layers at 0.15mm layer height, which results in a constant wall thickness of 045mm. This gave me the possibility to use the same specimen for the tests where I crushed the blocks from the top as well as from the sides and therefor make the results more comparable. I’’m well aware that this shell will add additional strength to the structure, so we are not purely testing the infill, but since it is the same for all, we can still compare results. I haven’t tested all of the patterns available and tried to concentrate on the in my opinion. Most relevant ones, which are Rectilinear Grid, Triangle Cubic Line, Honeycomb, 3D honeycomb and Gyroid. The way how the parts will probably fail in such a compression test is usually not compressive, yielding of the structure, but the stability failure buckling of a wall, which then leads to more load on the rest of the part and therefore fatal failure. The shape of the infill or even how the infill supports the external shell will determine how and at what load the structure fails. The slenderness of the structures will play a huge roll and curved structures, Like, for example in the gyroid will act like ribbing and improve strength. I am a little limited by my test machine because it unfortunately stalls at around 35kN or 340kg of load. So I only used an infill ratio of 10%, Unfortunately, as I also already talked about in a previous video. 10%, Infill does not results in the same amount of material used for each of the samples. Most notably a part with 10%, 3D honeycomb infill weights, almost double one with 10%, rectilinear infill. Either that’’s a bug or the generation algorithm is strange. Anyway, so at first, I printed a batch of samples all at 10%, weight them and then adjusted the infill ratio slightly, so that all samples roughly weight the same in the end that I used for testing. Before we take a look at the strength of the infill patterns, lets at first take a look at the printing time because this is also something that is well relevant. Most of the infill patterns take around the same amount of time to print only the Honeycomb structures take way longer due to the constant change of printing direction, where the printhead has to accelerate and decelerate constantly, which wastes a lot of time. Also, at least I have the fear that my printer rattles itself apart after a while when I use these Patters. Interestingly, the gyroid infill that also consists out of a lot of Tun’s doesn’t take much longer to print than the other more standard patterns. Due to the nice, smooth turns that the printhead does where accelerations are much smoother, so a kind of constant line velocity can be kept. I printed all of the samples in Formfutura’s Premium PLA on my original Prusa i3 Mk2s. Now let’’s come to the destructive tests. I’’ve been testing each patter once in the build direction and once from the side. Let’’s start with the pattern. I mostly use for my prints, Which is rectilinear infill. The first sample failed at 309 kg of load. Whereas if you load it from the side, it was only able to bear 191 kg, which is almost 40% less. Keep in mind that these samples are only 22mm in each dimension. So this amount of load is already quite impressive. Unfortunately, the cubes of the Grid Triangle Line and Honeycomb Patters were too much for my machine and it stalled for all of them at around 350kg of load. Taking a look at the samples still already showed that they were just before failing because the outer walls already showed buckling marks. So, for these samples, we don’’t really have an exact value to compare against, but if we still look at the transverse strength, the other loading direction is at least 30 to 45% weaker. The interesting results are now the 3D infill patterns where all performed very comparable in the Z direction. If we also take a look at the strength, 90° rotated cubic and gyroid infill perform exactly the same, just as claimed Only the 3D honeycomb performs about 15% worse. So which is now the best infill you can chose? Well, that depends I’’m still a huge fan Rectilinear infill If your parts don’’t require a huge amount of strength. It prints almost the fastest and it’’s the infill that has the densest structure, which is great for your top layers, so reduces pillowing even at low infill ratios. If we take a look at the numbers, the line infill pattern might even be better since it has higher strength values, prints faster and the infill spacing is almost as dense as with rectilinear. If you have a part that is purely loaded in compression honeycomb might still be the way to go, but prints quite long and might rattle your printer apart. Triangle infill might be an alternative, maybe a little weaker but prints much faster. For the 3D infill patterns, 3D honeycomb is dead in my opinion Cubic and Gyroid infill perform pretty much the same. Just the infill spacing is a little denser with the new contestant and come one. It definitely looks cooler. So in summary, I probably might be using line infill for any esthetic parts and quick prints in the future and anything that will see some load. Gyroid infill will be my new way to go due to its good and uniform strength in all directions. Now, I’’d really like to know from you guys. If I’ve missed something. And which investigation you’d really like to see in a future video, just leave a comment down below. I hope you like the video and learnt something. Please leave a thumbs up. I spend quite a lot of time in my research, so if you want to support the making of these videos than consider becoming a patreon and take a look at the affiliate links down in the description. Subscribe to the channel. If you haven’t and take a look at my other videos, Thanks for watching AUF wiedersehen. And I hope to see you around next time.