Sciencemadness Discussion Board

Pressing and casting charges

joseph6355 - 4-4-2018 at 00:38

I found that pressing seems to be very difficult without power tools.

Lets take Picric Acid for an example since it is one of the most discussed HE in here.


Chemistry of Powder and Explosives - Page 166

Assuming that a density of 1.672 g/cm³ was being aimed for, a pressure of 2060 kg/cm² would need to be applied according to COPAE.
A designated cylindrical charge of 48 mm in diameter would have to get pressed by over 37265 kg of force in order to obtain a density of 1.672 g/cm³. Such force cannot be applied without the use of hydraulic tools such as a hydraulic press.

Using a lever, things get a bit out of perspective.
I will consider that a healthy and young average man can lift a weight of about 100 kg.
For 37265 kg of force be applied at the end of the lever, such lever should be over 30 meters long (!!), and the length between the load of 37 tons and the Felcrum only 9 cm. This is absurd.

Pressing does have an advantage over casting, such as higher density and VoD, but the cost and difficulty to obtain these higher densities (specially with bigger crystals) is highly discouraging for the amateur when pressing at relatively high diameters.
The main problem with casting is the danger of inhaling fumes and even explosion, as noted by Yamato71 user.

I would like this topic to become a place for discussing loading (casting or pressing) charges of any form.

[Edited on 4/4/18 by joseph6355]

XeonTheMGPony - 4-4-2018 at 03:36

Pneumatic hydraulic press, remote operation! not very expensive if you have larg box store tool suppliers.

joseph6355 - 4-4-2018 at 14:57

Quote: Originally posted by XeonTheMGPony  
Pneumatic hydraulic press, remote operation! not very expensive if you have larg box store tool suppliers.

What is expensive to you?
I don't know about you, but I work at mc donalds bro (for real) :(


XeonTheMGPony - 4-4-2018 at 16:38

4ton is allot cheaper, try doing your conversions and figuring what ya actualy need

FYI only two of those are actual straight presses!

https://www.princessauto.com/en/detail/50-ton-pneumatic-hydr...

https://www.princessauto.com/en/detail/30-ton-pneumatic-hydr...

https://www.princessauto.com/en/detail/20-ton-hydraulic-shop... manual but gives you an idea.

https://www.harborfreight.com/6-ton-a-frame-bench-shop-press...

[Edited on 5-4-2018 by XeonTheMGPony]

[Edited on 5-4-2018 by XeonTheMGPony]

Metacelsus - 5-4-2018 at 04:29

How could pressed picric acid attain a density greater than cast picric acid (1.74 vs. 1.64 g/mL)? If the cast picric acid has no air bubbles, then shouldn't it have the maximum possible density for picric acid?

Rocinante - 5-4-2018 at 13:54

Yamato71 didn't experience explosion due to casting, stop this nonsense before it becomes a widespread myth. He experienced a simple detonation due to direct contact of ETN with a hot plate (after the MeOH evaporated in a second or two).

Meta: the crystals formed after casting can have lower density than the pressed ones (temperature change). It depends on the type of explosive compound but it is true that casting will tend to produce higher densities.

[Edited on 5-4-2018 by Rocinante]

RogueRose - 5-4-2018 at 14:24

Here are some 20 ton presses that can work well

https://www.ebay.com/i/252522257011?chn=ps&dispItem=1$238

https://www.northerntool.com/shop/tools/product_200641794_20...$150

[url]https://jet.com/product/detail/7910ab89bd564e349d685000fbda0aba?jcmp=pla:ggl:nj_dur_gen_automotive_parts_accessories_a1:automotive_parts_accessor ies_automotive_tools_equipment_other_a1:na:PLA_785913087_42857362764_pla-305510195670_c:na:na:na:2PLA15&code=PLA15&pid=kenshoo_int&c=785913087&is_retargeting=true&clickid=9 d1eb58b-3249-41c7-8214-e6582106a115&gclid=Cj0KCQjwkpfWBRDZARIsAAfeXarhf7DTGrW10fn5X3VWZObmWqw_ttoavxJx7eZeKwm4o9amG4kDLxMaApGbEALw_wcB[/url]$390 - air powered hydraulic

[Edited on 4-5-2018 by RogueRose]

joseph6355 - 6-4-2018 at 01:03

Quote: Originally posted by Metacelsus  
How could pressed picric acid attain a density greater than cast picric acid (1.74 vs. 1.64 g/mL)? If the cast picric acid has no air bubbles, then shouldn't it have the maximum possible density for picric acid?

I have no idea, but the crystal density of picric acid have been reported 1.763 g/cm³.

[Edited on 6/4/18 by joseph6355]

Microtek - 9-4-2018 at 00:19

Other compounds react quite differently to pressing. Maybe you should just choose another explosive; many energetics can achieve respectably high densities (within a few percentiles of theoretical maximum density) with pressures that are obtainable with a bench vise (at least for smaller diameter charges).
Also, you can reduce the required pressures by adding something that can lubricate the crystals, eg. wax, graphite or binder/plasticizer systems.

[Edited on 9-4-2018 by Microtek]