RE: powder packing density!!!

From: Neil Hopkinson <>
Date: Mon Feb 23 2004 - 19:58:33 EET

I seem to remember reading that the ideal diameter ratio for one mode to the
next is 7:1. So ideally particles would be mixed with diameters with 1st
mode = 1 micron, 2nd mode = 7 microns, 3rd mode = 49 microns, 4th mode = 343
microns etc. I'm not suggesting the use of 1 micron powder but hopefully
you get the idea.


-----Original Message-----
From: []On
Behalf Of Miller, Michael W
Sent: 23 February 2004 14:04
Subject: RE: powder packing density!!!

I've always wondered, what's the packing density for spheres?

Bear in mind most powders have a range of sizes, hence tighter packing =
is obtained as the smaller particles fill up the spaces between the =
bigger ones. Also when dealing with powder, other factors such as flow =
are affected by non-round shapes.

Michael W Miller ( =20
The Boeing Company M/C 45-17 A-2329 206-655-3289
Rapid Product Manufacturing 655-4366 655-4365 655-2262 =20

Disclaimer: Engineer and out the other!
Experience is something you get right after you need it.

-----Original Message-----
From: Toby Gill []=20
Sent: Friday, February 20, 2004 4:34 AM
Subject: powder packing density!!!

Thought this may be of interest to some,

It has just been published that M& M sweets pack together more densely =
perfect spheres when randomly jumbled in a container.
It was also discovered that by stretching the M&M shape (so elliptical,=20
like an almond) in computer simulations, a packing density approaching =
packing fraction of 0.74 was achieved.

This seems to me to be important to anyone involved with producing=20
components from powders, be it by conventional methods or by rapid=20
manufacturing techniques. Does anyone have any comments/thoughts on this =


P.S. I have just finished a PhD based on SLS and am currently looking =
employment. Anyone who has any vacancies arising in the near future =
contact me at the email address above.


Toby Gill
Received on Tue Feb 24 07:40:37 2004

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