Tribology question
Tribology question
(OP)
I have a problem with a paste that I am attempting to extrude through a glass syringe. The paste is about the consistency of toothpaste and has very small (under 150 micron) particles suspended in it. When I attempt to apply a constant load to the teflon pusher of a glass syringe, I do not get a constant flow rate. When I lubricate the system with a PFPE lubricant (which is not soluble in the paste or any of its components) it seems to get a little better, but I still don't get a constant flow rate. Does anyone have any experience with extruding pastes and or tribology that can help me take this problem apart. One interesting thing that I noticed is that the paste seems to stick very well to stainless steel, so I'm wondering if it is sticking to the glass as well, causing the system to bind.





RE: Tribology question
What max pressure can you withstand? (Hand only?)
2. What length needle, and how is the needle detailed? What ID, what OD?
Double opening, single cut-off tip, slanted end?
RE: Tribology question
2. I'm not using a needle on the syringe, there is an opening on the end of the syringe that is 0.074" in diameter.
This is merely a test setup to determine the flowrate vs force relationship of different formulations of the paste and at different temperatures.
Does that help?
RE: Tribology question
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RE: Tribology question
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Did it ever work the way you intended?
TTFN

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RE: Tribology question
RE: Tribology question
RE: Tribology question
I think that was essentially my point. Your "particles" are relatively large, and you seem to be saying that the particle loading is high, both of which are not conducive to smooth flow. You should at least try a run with your mixture with a lower load, or a wider orifice, and see if that changes things.
TTFN

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Need help writing a question or understanding a reply? forum1529: Translation Assistance for Engineers
Of course I can. I can do anything. I can do absolutely anything. I'm an expert!
There is a homework forum hosted by engineering.com: http://www.engineering.com/AskForum/aff/32.aspx
RE: Tribology question
150 um ~ 0.006" so the "opening" is about 12 particles across.
http://assets.nydailynews.com/polopoly_fs/1.160363...
What is the detail of the transistion connecting the "opening" and the end of the syringe?
Is the "opening" part of a separate component screwed on to the end of the syringe?
Are there any shoulders or steps in the transition?
Depending what you are starting with, Perhaps a gentler smoother profile would help buy some consistency.
For gravity fed systems the transition is very important to prevent a variety of problems.
"first in, first out, bridging, rat-holing"
https://www.youtube.com/watch?v=PmTnUOcAnuY
https://www.youtube.com/watch?v=H6llvgfTkJE
http://jenike.com/case-study-search-results/