Not really necessary unless you’re into casting tiny volumes of metal. Like
jewelry where the metal geometry is important.
John
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On ;
Behalf Of William Claybaugh
Sent: woensdag 29 januari 2020 18:51
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Vibratory compaction
Shane:
Is this done after or during mixing?
If the latter, I—and I suspect others—would be very interested in your process:
for example, how long do you apply vacuum / vibration before casting the
grain(s)? Have you documented the difference in final propellant density?
I found that 10 minutes under vacuum after mixing resulted in density going
from 0.055 to 0.058 lbsm. / cu. in., for a specific propellant formulation, for
example. Do you have a guess as to what additional density might be achieved
from vibration? Note that theoretical is 0.065 for this propellant.
I’m trying to make an economic calculation here: for my next generation
(composite) 6” motors, getting to 0.060 lbsm. / cu. in. Increases propellant
fraction from 70% to 72%; given my estimate of the cost of a vibratory table,
I’m looking to understand if that investment produces greater performance gain
than alternative weight saving investments.
Bill
On Wed, Jan 29, 2020 at 10:34 AM <spcdestiny01@xxxxxxxxx> wrote:
At my school we use the vacuum while it’s on the vibration table to remove all
air bubbles and increase the density.
Hope that helps,
Shane Cullen
Sent from my iPhone
On Jan 29, 2020, at 10:27 AM, William Claybaugh <wclaybaugh2@xxxxxxxxx> wrote:
Anyone have experience w/ vibratory compaction if solid rocket propellant,
with or without vacuum?
Initial search did not turn up anything specific....
Bill
