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Q: Sorting mircrospheres ( No Answer,   1 Comment )
Subject: Sorting mircrospheres
Category: Science > Instruments and Methods
Asked by: ministry_92-ga
List Price: $200.00
Posted: 16 Sep 2005 11:20 PDT
Expires: 14 Dec 2005 05:31 PST
Question ID: 568802
I need someone to physically sort perfectly spherical rigid beads
(50micron to 1000 micron diamter) with a +/- 50 micrometer tolerance.

The provider must be in the US, must be experienced, must currently
offer this service.

The provider will probably need drum sieving capability.

For the question to be answered, please provide the company(s) that
meet the requiements with contact infomration.

Possible search/key words:
Drum sieving
Particle size distribution
Particle size
Screen sieve
Particle separation

  This is not to be confused with Mole sieve or molecular sieve

Request for Question Clarification by pafalafa-ga on 17 Sep 2005 06:42 PDT

A few questions, if I may:

--What sort of volume of material are you talking about -- ounces?  pounds? tons?

--is it a one time batch, or an on-going capability that you need?

--I think of drum sieves as usually applying to pretty large particles
-- are you aware of drum sieves that can do micron-sized particles?

A bit more context would be helpful in trying to track down the right
service for your needs.



Clarification of Question by ministry_92-ga on 17 Sep 2005 18:23 PDT
Thank you for your interest.

We would be looking to sort 1 KG of beads with the specified tolerance.

this would be an ongoing requirment.  We would need to sort this
quantity 2 times a month.

I am not aware of any capabilities of drum sieves, however, your
expierences with such technologies are certainly beneficial.

What specifc context do you require?

Request for Question Clarification by pafalafa-ga on 20 Sep 2005 19:19 PDT

I haven't been successful in finding a service that is willing to
handle such a small quantity of material on a routine basis.

However, it seems possible to set up your own in-house sieving
operation at a fairly modest cost.  It doesn't take large-scale
equipment to handle a couple of kgs.

Take a look at the sieves offered here:

and you might want to even give them a call to discuss your situation.  

Let me know what you think.

If you absolutely need to outsource this task, let me know that as
well, and if you can, tell me what the particles are (plastic?) as
this makes a difference.



Clarification of Question by ministry_92-ga on 21 Sep 2005 05:53 PDT

    I appreciate your enthusiasm to answer this question.  It is
common for particle agglomeration to increase as the particle size
decreases.   This tendency requires special classification processes
that is beyond the capability of the site you recommended.

Clarification of Question by ministry_92-ga on 21 Sep 2005 05:54 PDT
The particle are as hard as glass
There is no answer at this time.

Subject: Re: Sorting mircrospheres
From: cat111-ga on 14 Dec 2005 00:20 PST
I am a scientist working for a pharmaceutical company, and we use
sieves like the ones shown on the internetmesh page to test the
particle size distribution in the raw materials used in the drugs we
produce.  We clamp the sieves in series onto a vibrating platform
which helps to force the sample through each sieve.  Some products do
tend to aglomerate a lot, but if your beads are "as hard as glass" I
think that the vibrations should break the agglomerations apart.

You should aslo state what increments you require the sample to be
divided into.  For example, 10 steps from 45 microns to 1000 microns
at equal intervals.

Another device I have heard of (have not used) is the "Alpine Air Jet
Seive" which uses air to force the particles through the series of

Although these options are usually for smaller amounts than 1kg, it
would be possible to repeat the process until the 1kg is sorted.

You could try looking for contract laboratories, eg for the
pharmaceutical industry, they would have equipment at a small scale (I
will let pafalafa do this).

I am not sure what you mean by "special classification processes".

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