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extrusion PMMA  

 
Konst2018
(@konst2018)
Member
Good afternoon. I would be grateful if you advise the settings for the production of PMMA filament
Quote
Posted : 04/03/2020 11:17 pm
louis
(@louis)
Member Admin

Hello @konst2018 ,

 

Thank you very much for your question ; I will try to help you the best I can.

Each grade of PMMA being unique, we will have to find optimal settings for your grade specifically. Do you have the datasheet of the material?

Have you experimented with PMMA already a bit ? If yes, can you please share your parameters and observations with me ?

 

Unfortunately there is no definite way to predict what settings will work best for your material. The way to proceed is to follow a step-by-step methodology, which will help you understand how the material behaves, and therefore lead you to the optimal settings : https://support.3devo.com/how-to-start-the-extrusion/

You can start your experiment 10-20% above the melting point, as described in the methodology, and then you can adjust the temperatures, 5C by 5C, and observe the results. If you manage to log your experiment with DevoVision, as described in the methodology, I would be glad to have a look at the graphs and help you understand what happens.

 

Is the method clear to you ?

Please let me know how I can help you further.

Looking forward to hearing from you

 

This post was modified 3 months ago by louis

Best regards,
Louis

ReplyQuote
Posted : 05/03/2020 11:19 am
Konst2018
(@konst2018)
Member
Good afternoon, thanks for the response.
I am using ACRYREX CM205
temperature №1 210, №2 260, №3 260 and №4 230 rpm 6 fun 50%. d 3,0 mm
I think the quality is not very good, there are a lot of air bubbles
 
ReplyQuote
Posted : 05/03/2020 10:19 pm
louis
(@louis)
Member Admin

Hello again @konst2018

Thank you for this additional information.

I searched your grade online, and I have found that it is a high viscosity grade. This is a good thing, for it helps build up pressure in the barrel and give the flow a lot more consistency.

Bubbles in the filament can be explained by a few different reasons :

  • residual moisture, if the plastic has not been dried properly. In this case, based on the information I have gathered, PMMA is hygroscopic (absorbs moisture) and needs to be dried for 2-4h at 90C. 
  • plastic degradation and outgassing, if the temperatures are excessive. Maybe 260C on all heaters is too high.
  • air trapped inside the melt, if the temperatures are excessive too close to the feed zone (H4 mostly)

Have you experimented with other temperatures ? For example I see a very big difference between H1 and H2 in your case ; this might cause flow inconsistency. It would be worth going trough the whole methodology to get a better understanding of the plastic behavior. It is sometimes possible to process PMMA down to 210C. By decreasing the temperatures slowly down to this range, you might see a significant improvement.

Can you trying adjusting the temperatures and log the experiment ? https://3devo.com/devovision/download/

Please let me know if my explanation was clear, and please keep me informed about your tests so I can help you further get good filament !

Best regards,
Louis

ReplyQuote
Posted : 06/03/2020 11:43 am
Konst2018
(@konst2018)
Member
Good afternoon, thanks for the help, 
I will continue the experiments, I reduced the speed to 4 and dried the plastic for 4 hours
at a temperature of 70.
The quality became better
. I'll try to lower the temperature
ReplyQuote
Posted : 12/03/2020 5:51 am
louis
(@louis)
Member Admin

Hello @Konst2018 ,

Thank you very much for keeping me informed.
It is good to see that you are currently improving the quality of your filament.

Please feel free to shre pictures or logs with me, so I can try to analyze and give you specific tips.

Of course, be careful not to decrease the temperatures too fast and clog your machine, and make sure you purge your machine at the end of each session using HDPE (and maybe DevoClean MidTemp once a week).

Please let me know how your experiments go; it is always a pleasure to help.

Best regards,
Louis

ReplyQuote
Posted : 12/03/2020 9:41 am