[THEORY] PLA Temperature / Melting Point Tempering

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Liquid
Posts: 579
Joined: Sat Feb 16, 2013 12:46 pm

[THEORY] PLA Temperature / Melting Point Tempering

Postby Liquid » Wed Apr 24, 2013 6:31 am

I purchased Pink, Black, Red and Silver PLA. Colors are awesome and the price is decent compared to the rest of the market.

Im moving on to printing with pink right now, and in order to not get jams I have to print at a temp of 200 degrees Celsius. The pink averages out to 1.7 at this point in the spool.

The left over yellow I have prints at 190-195 very well (190 being better than 195) 185 nor 175 for that matter work very well. The yellow averages out to 1.73mm

This got me to thinking about "why" different spools may print at different temperatures. I mean Im sure pigment and diameter have a small amount to do with it, but I doubt it is the main reason behind it. As you can see above the pink averages out smaller yet needs a higher temp.

Soldering came to mind. (Those who solder a lot or rework electronics prob know where I am going with this.) Sometimes I dont feel like messing about when Im removing components from electronics to replace them, so I crank my soldering iron up and get to it.

If I were to set my iron on a lower setting, it will melt the solder beautifully, just a few seconds longer. If I crank my iron up on the same board, same thing just faster.

HOWEVER with one major difference. The solder excess left on the copper pads needs to be removed in prep for the new component. Whats interesting is that the areas I heated with the iron cranked up, wont remelt unless my iron is at least that same temp as before. The area melted with the iron on low will remelt as long as I am at least on that low settings, but once I crank the iron up again, that area too has become "tempered".

This is why on some solder joints, you get globs when trying to rework old solder, if the iron isnt at the same temp as was used to install that component.

So in a nutshell, if pink needs 200 degrees Celsius to melt, odds are, thats simply the temp that was used when it was turned from beads to 1.75mm filament.

Not sure why this is even important, and I have no clue if its even accurate, but after working with solder for so long, it doesnt sound too crazy to me.
Last edited by Liquid on Thu May 02, 2013 5:14 pm, edited 1 time in total.

Rodwagner
Posts: 261
Joined: Mon Dec 03, 2012 5:00 pm

Re: PLA Temperature / Melting Point Tempering Theory

Postby Rodwagner » Wed Apr 24, 2013 7:50 am

Find color to be a factor but not so much with latest TAM filament. Difference between translucent and solid makes a bigger difference. Translucent melts at lower temp. The speed and head size make for some major changes in print temperature. The faster you are printing the higher the temp. The environment also seems to be a factor running hotter in winter than summer. I have a Dual and the stepper motors are more powerful and that makes a difference. I can print at lower temp and still extrude. Spent a month just running tests to determine optimum printing temps and then TAM changed filament composition. What I did come away with was how all the variables came into play and how to make adjustments. Isolating just one factor and then studying the effect of varying that factor and looking at results. That's why I made the fusion test column. Run it when I get new filament. Found TAM's latest to be running at hotter temp than older material. You have to pay close attention to fusion strength. Sometimes printout looks good but has poor fusion between layers. Tempering is a interesting factor that could come into play. I agree with your assessment on soldering. That might account for same color, same brand working best at two different temps depending on what batch it came from.

Liquid
Posts: 579
Joined: Sat Feb 16, 2013 12:46 pm

Re: PLA Temperature / Melting Point Tempering Theory

Postby Liquid » Wed Apr 24, 2013 10:55 am

Here are some pieces I printed for a start of a portfolio.

100 micron resolution, 10 percent infill, 60mm/s. 3 loops 1mm wall thickness. Each piece took around 1 1/2 hours.

The Yellow, Black and Silver all printed at 185-190 degrees. With no problems or jams if the nozzle dipped to 185 or so.

The Red and Pink would jam when the nozzle dropped in temp, but they printed just fine at 200 degrees, with no problems if the nozzle dropped to 193ish.

I think the red and pink were probably extruded into filament at about 195-200 degrees, and tempered because of it.
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LaserGnomes
Posts: 1058
Joined: Thu Dec 06, 2012 10:15 pm

Re: PLA Temperature / Melting Point Tempering Theory

Postby LaserGnomes » Wed Apr 24, 2013 2:44 pm

Dime bottle openers?

Liquid
Posts: 579
Joined: Sat Feb 16, 2013 12:46 pm

Re: PLA Temperature / Melting Point Tempering Theory

Postby Liquid » Wed Apr 24, 2013 3:20 pm

Close, penny bottle openers.

http://www.thingiverse.com/thing:9496

Using them to show off some of the colors.

jbrisbin
Posts: 80
Joined: Fri Mar 15, 2013 12:37 pm

Re: PLA Temperature / Melting Point Tempering Theory

Postby jbrisbin » Thu Apr 25, 2013 11:16 am

I seem to recall that polymers like PLA have chains of repeating sequences of the primary compound repeated variable numbers of times. In other words, each molecule in the mix is not the same length. One might be 100 units long, another 20 units long.

There is a distribution of such lengths in every batch of polymer and the mean value of those lengths can alter fundamental characteristics of the plastic. Importantly, different samples from different vendors are certain to have different distributions of chain lengths based on the process conditions under which they were formed.

Even if the melting point does not change dramatically, preparations that have longer chains will be more viscous when in liquid phase than those with shorter chains at the same temperature.

It may be that the melting point is not really changing much but, containing longer mean chains, that it requires a higher temperature to get the viscosity down to the point where it extrudes well.

There may even be a 'tempering' effect where chains get longer when extruded at higher temps, but I would think they might break down to shorter lengths as the temperatures go up beyond some point.

Perhaps someone with a more than nodding acquaintance with polymer chemistry might have an opinion?

LaserGnomes
Posts: 1058
Joined: Thu Dec 06, 2012 10:15 pm

Re: PLA Temperature / Melting Point Tempering Theory

Postby LaserGnomes » Thu Apr 25, 2013 4:10 pm

Makes sense honestly. We've known for a while that production batches vary the quality specifically.

That said... sounds like.. run hot without breakdown and then cool quickly to counter that.

Would agree there is a kind of "tempering" effect at certain tempatures. Rod has a temp test tower which he uses to test various new pla's when he gets them. It runs tempature steps and once printed he can apply lateral pressure to the joints and the first to break is the weakest.. and repeat that down until the right range is detected for that particular batch of pla (regardless of color or maker as each roll is tested)

-2 cents.

Liquid
Posts: 579
Joined: Sat Feb 16, 2013 12:46 pm

Re: PLA Temperature / Melting Point Tempering Theory

Postby Liquid » Thu Apr 25, 2013 4:31 pm

LaserGnomes wrote:Makes sense honestly. We've known for a while that production batches vary the quality specifically.

That said... sounds like.. run hot without breakdown and then cool quickly to counter that.

Would agree there is a kind of "tempering" effect at certain tempatures. Rod has a temp test tower which he uses to test various new pla's when he gets them. It runs tempature steps and once printed he can apply lateral pressure to the joints and the first to break is the weakest.. and repeat that down until the right range is detected for that particular batch of pla (regardless of color or maker as each roll is tested)

-2 cents.


Thats a really good test. Maybe rod could share the file??? hrmm? Hrmm?

LaserGnomes
Posts: 1058
Joined: Thu Dec 06, 2012 10:15 pm

Re: PLA Temperature / Melting Point Tempering Theory

Postby LaserGnomes » Thu Apr 25, 2013 7:26 pm

It's on the forum several places.. will add it to the google drive once I find it.

eeyore
Posts: 125
Joined: Tue Oct 16, 2012 8:09 pm

Re: PLA Temperature / Melting Point Tempering Theory

Postby eeyore » Mon Apr 29, 2013 8:44 pm

In the past I did some test prints at different temps with different colors. Currentily I can print with Orange, White, Light Blue, Blue, light Green and Orange at 185C with no problems.

The color that is giving me a difficult time is Red. This color will consistently cause a jam pretty quickly. I will do some test at higher temps, 195, 200, 210.

When reading different 3D print forums, I see people running PLA at much higher temps than 185C, they are often at 200 or 210. I thought that the higher temps would cause problems with PLA.

FYI the site I purchased the Red PLA from says that 185C is the best temp. I've purchased a lot of PLA from them and have not had a problem. This is the first time I've used Red PLA.


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