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michael.b36
(@michael-b36)
New Member
Printing temperature

Hi

I have been printing a lot of structural parts lately, and I noticed that the strength of my parts heavily rely on my printing temperature. I think this has something to do with layer adhesion.
However, increasing the temperature to much causes print deformation (such as bad surface finish and blobs) .

While these parts, printed at higher temperature, don't look very good they are structurally much stronger. This got me thinking about tweaking some settings in my slicer to allow for higher temps for infill and and inner perimeters and let my outer perimeter print at a lower temp(and possibly slower speeds) to better the surface finish while still having a strong part.

I have not been able to find any setting which allows me to change the temp of my outermost perimeter, is there a way to achieve this?

Posted : 05/05/2017 7:38 pm
roger.s5
(@roger-s5)
New Member
Re: Printing temperature

You should check the material data sheet. It contains every specification and ways to get the best results. Otherwise, you should consult with the person who has already used the same material and printer that you are using.

Posted : 09/05/2017 9:33 am
JuanCholo
(@juancholo)
Honorable Member
Re: Printing temperature

there are limits. as i discovered, and you are discovering you cannot 3d print everything you imagine.

there are very limited boundaries when 3d printing with layers.

layer adhesion: you have to get the material hot enough to bond 100% but the heat is so high that you can melt small areas, so you increase cooling to compensate and you introduce weakness and brittleness into the shape you are making.

anything under 10mm is a major problem when strength is needed. some materials even have this in the fine print about small parts not being possible.

Lets take some examples
Abs and nylon.

start with Nylon : you have to layer it at over 240C the closer to 260C the better however you can't because of Oozing and cooling. print head limitations.

The second you exceed 10% cooling Fan at 245-255 degrees with nylon it will De-laminate (not adhere strongly to the layer below.
so you have to drop temperature to compensate for lost cooling fan. and the floor is around 240, under 240 once again layer bonding is greatly effected.

that leaves you with a narrow range. anything under 10mm will start to become a melted mess because you need strength.
you also have to factor in nylon shrink is horrible at least .5mm of tolerance compared to ABS that can be zero tolerance depending on type of ABS.

ABS is has a little wider range you can add more fan or reduce heat some more before the material really gets weak. however ABS is Weak no matter what.

Nylon is stronger then ABS but nothing will be an strong as an injection molded version of your print.

An enclosure around the printer to trap heat helps a lot. Cooking the Filament with heat to remove water trapped inside helps big time.

but there will always be dimensional limits.

Copying an injection mould design for 3d print means you will discover some parts of it are impossible to create on the 3d printer directly.
Or you will need to see what kind of failure you had and if it is possible to alter the design to make it work.

for example stark Edges are brittle. because the materials ability to hold heat changes and so an area will shrink faster in one area compared to another while the layer is going down you get micro fractures as it cools and the part will most likely split there when force is applied.
so you need to add a chamfer to gradually change dimensions giving that area a beef up or more thermal protection. you may need to thicken an area up greatly so it no longer looks like the original part but will have the strength you need to hold up as a 3d printed item.

you may need to start thinking outside of the box a little. instead of directly making the 3d printed part, consider making the 3d printer create a mould of the part which you will cast using resin or injection moulding equipement on.

it doesn't defeat the purpose of the 3d printer if you are starting with a part that does not exist you create a PLA model, output the part check fit, then invert the part inside of your 3d software inside a solid split the mould for casting with keys then 3d print the mould from Flexible nylon or ABS (to be recast in RTV later) then you could have complex moulds to cast parts from in a material that has strength under 10mm of area.

or you have to scale everything larger 1.25 times to make it work.

take the open R/C project as an example everything is about 1/8th scale. 1/10 scale presents big problems you can make parts smaller but they will have VERY little strength due to the cooling required.

so making pretty parts doesn't work if they need to work. ugly parts have strength but may not have function if they don't fit in the way you need them to.

basically you have to become your own engineer and materials specialist as there is no combination of slicer settings that will work for all your needs you will hit roadblocks you may not be able to pass without creative thinking or not using the 3d printer directly.

another example. I needed a small detailed gear with 41 teeth under 48 pitch as a face gear.
I created the model in fusion to perfection
then attempted it with ABS. the printer could not create the gear. the teeth were too small and the material had no strength due to cooling requirements to hold shape.

i played around for a week tried Nylon (even worse) no combination would make this gear work as a 3d printed item.

however i could create a blank rough shape of the gear without the teeth profile which required no fan and had the material at full strength.

Thus i created the blank gear shape with little guides on the top in the form of .4mm lines which i could follow with my machine tools so i created a gear blanks with 41 spots for a tool to rest on that would fit my fly cutter and i cut the teeth in by hand one at a time to complete the task.

so 3d printing got me about 50% from nowhere to somewhere but it could not get me 100% right off the bat.

“One does not simply use a picture as signature on Prusa forums”

Posted : 09/05/2017 6:26 pm
Hackinistrator
(@hackinistrator)
Trusted Member
Re: Printing temperature

try annealing the parts after printing

Posted : 12/05/2017 2:33 am
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