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Material Properties and Strengths (Filaments)

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I MADE A BETTER AND INTERACTIVE GRAPHS HERE:

 

 

 

http://gr5.org/mat/

 

 

 

Okay well this post will grow when I add temperature properties.  I've been thinking about posting this for a few years.  Here is a graph showing some mechanical properties of some common filaments.  Please read explanation as this is a complicated subject.

 

Click to zoom in on chart (click 3 times - first click zooms, second click jumps to actual image, third click zooms into that).  Higher up is stronger.  Farther to the right is stiffer (not steel).  Both axes are logarithmic.  Most data is published by various manufacturers.  I have personally verified a few of these numbers with my own equipment.

 

materials.png

 

VERTICAL AXIS

So the vertical axis is tensile strength.  It's measured by pulling on a cylinder of material from each end until it breaks.  Divide the force by the cross sectional area and you get the strength in psi (pounds per square inch) or MPa (mega pascals) for those who prefer metric (like me).  Anyway this is kind of complicated because the materials towards the left are quite stretchy and long before their breaking point the parts are damaged.  The point where it won't bounce back is the yield strength but I choose the ultimate aka breaking strength.  Or whichever was higher (some materials actually start to get weaker again - like steel.  Or PLA).  Now the weakest material shown, PP is actually showing the yield strength - it is actually much stronger than you would think so this is unfair.  But the machine that UM used to test PP wasn't long enough to test this value (the part never broke).

HORIZONTAL AXIS

This is the tensile young's modulus wherever possible (sometimes it's the flexural modulus which is close enough). This is tricky and complicated but for the most part indicates how stretchy/flexible a material is.  So ninjaflex on the left edge has very similar flexibility to a rubber band.  Most nylons (except shapeways) are much more flexible than PLA or ABS and this makes them very tough.  Materials to the upper left will be tough as hell.  In fact anything to the left of and including "nylon UM" can probably be driven over by a car and come out just fine afterwards.  Or a tank.  Or you can throw it against a brick wall with full strength or hit it with a hammer.  Most of those materials in most shapes can handle it.  Tough.  Materials to the lower right are more likely brittle (hence glass is the most brittle).  XT is probably somewhat brittle among filaments (I've never tried it).  Materials to the right tend to be hard.  The hardness scale and the modulus are closely intertwined.  Things to the right are harder, to the left are softer.

Specific Materials

The table that created the graphs here is at the bottom of this post.  Red materials above are for comparison and are not filaments.  ABS is shown in green above - this shows how different people testing the same material get different results.   Most of these tests (maybe all) were done on printed parts which will be a bit down and to the left of injection molded parts.  Two different companies tested Taulman Nylon 645.  With professional equipment and also got different values hence the two data points.  UM=Ultimaker in the chart.  XT is colorfabb.  POMC is delrin.  I'm very skeptical about nylforce CF specs.  If someone wants to send me some I'll print and test it with my stress/strain machine.

 

 

 

 

materials_temp.png

 

In the graph above there are a few points to keep in mind.  Materials with low softening temp are the easiest to print because they don't warp much in the temperature range from this temperature to room temp.  It's only about 30C difference.  As you move to the right the yellow group of materials is a little harder - parts are more likely to warp off the bed so you need to learn some tricks.  Maybe. They really aren't much worse.  The orange area with ABS and other materials are tricky now for a few reasons - they don't stick as well to the bed, you are now getting into materials with layer adhesion issues so you need to lower the fans, the bed takes much longer to heat up - you really need to enclose the printer to raise air temp to around 35C to get decent quality.  The red group needs nozzles that can go over 300C (no teflon please!) and print beds that can go to 150C and ambient air in the printer at 80C.  So this requires special equipment.

 

Also as you move to the right your materials can handle working environments of higher temperature.  The green materials can't handle a car with windows rolled up on a hot sunny day (neither can a human for that matter).  The yellow materials can handle this but can't handle boiling water.  The orange materials can handle boiling water.

 

SOFTENING TEMP (horizontal axis)

In the graph above the horizontal axis is a mythical characteristic called "softening temp".  For many of these materials in the green and yellow area I have tested them myself personally by sticking them in hot water. Above a certain temp they can be easily bent and when they cool a few degrees they stay in the new shape.  That's what I call the softening temp but in reality this value came from HDT (heat deflection temp) or glass temp in other cases or functional temperature in other cases.  It's a mixed bag.  So it's very approximate!  Normally you want the heated bed at a temperature a bit above this temperature such that the material is soft enough to flex a little and spread out the warping forces. 

 

PRINTING TEMP (vertical axis)

Also somewhat arbitrary as some materials like PLA have a wide range of printing temps.  Also variation in heater block design and variations in nozzle length, filament diameter, airflow touching nozzle, and more - affect what this temp should be.  But it is a good place to start.  Mostly I'm just showing that the red materials need special equipment to print them.  The green, yellow, and orange materials can all mostly be printed by most printers no problem.

 

In table below, take all values with a grain of salt.  Especially temperatures.  For tensile modulus notes read "horizontal axis" paragraph far above.  For tensile strength read "vertical axis" far above.  For softening temp - please read "softening temp" paragraph above.

 

tabl.png

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Thanks @gr5 , very interesting! Thank you for your time in putting this together. 

I was wondering; for tensile strength is it relevant to mention with which print profile it was made, like layer height? (Do you know since you did not perform all tests yourself, but also collected data left and right?) Or was it tested in parallel with the direction of the printed layers? (Or are these pure material strengths, so not performed on a 3D print but just a string of filament?

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Most (maybe all) of these tests were perfomed on a printed part shaped like a bow tie but they were printed by different companies and using different printers.  The UM filaments were all printed by UM so you'd have to talk to them, lol.  Mostly each manufacturer printed the parts and sent them off to be tested or they had their own machines.  Anyway each company chose different nozzle sizes and layer heights and so on.  I've printed these "bow ties" myself and the best results come when you make the thickness a ratio of the nozzle width and you do all shell (no infill).  Thick layer heights (e.g. 0.2mm or more) and large nozzles (0.8) might give slightly stronger results but I suspect most companies used their default nozzle of the printer that was handy so probably mostly 0.4mm or 0.5mm nozzles.

 

More data to come!  Watch this space, lol.

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Thanks. These are very interesting data, and a very good starting point for selecting materials. Maybe this thread should be sticky?

 

Actually, I am a bit surprised at the positions of Taulman 618 nylon , and colorFabb XT and HT.

 

A suggestion: as you accumulate data, maybe you could add a sort of "error bars" to the values in the second graph (with green, yellow, and orange ovals)? Both horizontal and vertical lines. These error bars would indicate the useful range. Then for example PLA might sit at 210°C, but its error bar might go from 190 to 220°C. While another material at 210°C might only go from 205 to 215°C. This would give an idea of the useful range of the material, and how critical temperature settings are.

 

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The "softening temp" is the least accurate because it's usually glass temp (which can be less than 0C for something like nylon or ninjaflex which is useless info) or heat deflection temp which is also sometimes useless.  I'm pretty sure the softening temp is wrong for some of the items in the green area but I don't have any samples so I don't know for sure.

 

Most of these materials did indeed come with a printing range and so I picked a temp near the middle.  Some ranges were tight (e.g. 210-220) and some were loose like PLA (180-230).  It would indeed be great to have a min/max printing range pair of columns.  

 

 

 

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