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Topic: sensor for powder mixer (Read 579 times) previous topic - next topic

procrastinator

Oct 17, 2017, 05:33 pm Last Edit: Oct 17, 2017, 05:39 pm by procrastinator
do you have any idea what kind of sensor i will use to detect if a powder ingredients is well mixed? ill build a mixer that will mix a 2 kinds of fine powder and i really need a sensor that would say that mixing process is done by detecting if the ingredients is well distributed . bcs time-based is not allowed help me pls thanks

p.s wish its not sensitive in water too

jremington

#1
Oct 17, 2017, 05:54 pm Last Edit: Oct 17, 2017, 05:55 pm by jremington
Seems like an impossible task for a sensor.

How would you define "well distributed"?

wvmarle

Times may have changed, but...

Some 20 years ago I worked for a day in a mixing company. They were doing test mixes of up to a few tons. Out of curiousity I asked them, how they know whether it's mixed well. They basically answered that they generally don't know, that they can't tell, and simply mix for a certain time. The longer you mix the better the distribution is. You basically mix as long as you need to get the desired mix, which is largely based on experience.

If you have two materials with very different colour, e.g. black and white, or yellow and blue, you may get away with a colour sensor.

If two fine materials with the same or similar colour there's not much you can do other than taking samples and checking it carefully in the lab for consistency (making sure you don't mix it in transit to the lab or while handling it).
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

DaveEvans


procrastinator

iws thinking about color sensor too but i had a doubt, what if the part detected by the sensor is mix and reach the set point color but the other part is not well mixed. so it inaccurate

jremington

That is an excellent doubt!

procrastinator

or can you give me atleast a theory, or technical/ study that says time is very important in mixing process so that i can prove theres no other way but to use a time-based in my automated mixer. thank you so much

MorganS

To analyze this, you've got to simplify the problem. Think about shuffling cards. That's a kind of mixing. How do you define "adequately mixed" for a deck of cards?

Well, one way might be to say "How many times do I need to shuffle for there to be an equal probability for a card starting in any position ending up at the top of the deck?" That would really be thoroughly shuffled if the bottom card at the start had the same probability of getting to the top as the card which started at the top. I don't remember the details of the analysis but it does end up with a simple number like 7. If you shuffle the cards 7 times, the deck is totally shuffled.

So, for a particle of powder which started on the left side, can it end up on the right side of the mix? Well, one rotation of the mixer blades can move it only so far. So just count the rotations, which are probably at a constant speed, so you could also count time.

Once you've determined the number of minutes mixing required for your particular mixer, then you just always run it for that time.
"The problem is in the code you didn't post."

DaveEvans

#8
Oct 19, 2017, 06:07 am Last Edit: Oct 19, 2017, 06:08 am by DaveEvans
Not surprisingly, simply googling

powder mixing sensors

yields many hits, including one that promises  "continuous insight in the homogeneity of a mixture without interrupting the mixing process to take samples. This results in a clear picture of the quality of the mixture..."

MarkT

do you have any idea what kind of sensor i will use to detect if a powder ingredients is well mixed?
Sounds pretty much impossible in the general case.  So some specifics of which powders are involved
and there properties is a necessary starting point.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

wvmarle

or can you give me atleast a theory, or technical/ study that says time is very important in mixing process so that i can prove theres no other way but to use a time-based in my automated mixer. thank you so much
You still didn't answer the question which exact powders you are trying to mix.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

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