Pressing a comp with mixed Mg/Al in it.

[oldguy]

How many pounds of pressure is safe to use.

 

When pressing a composition into a tube that contains a mix of Mg/Al?

 

I am beginning to understand why many commercial flare comps often have 2 part epoxy like binders.

 

Simply because one part reacts with the other & they set up quickly hard as a rock.

 

In using binders like Gilsonite solution to make a thick paste of a comp.

 

Then hand tamping/ramming a tube full of that paste.

 

It takes forever to dry the tube content, even at 145 F for days.

 

I don't feel real comfortable going above 145F drying these puppies.

 

I have a hydraulic press & am thinking of far less binder & far more pressure.

 

To cut down on the drying & comp set up time.

 

Also, is it practical to built a hinged jig body to hold & press multiple tubes at once.

 

A hand pumped hydraulic press is one slow SOB, one at a time.

 

Hell, I am thinking a scissors type screw jack would be far faster.

 

As an alternative, I am thinking of going to a 2 part epoxy like type binder.

 

If I can find one that is easy & inexpensive to use.

 

Any suggestions?

 

EDIT TO ADD:

 

High end aviation, marine & military flares use Laminac 4110 epoxy & Lupersol DDM curing agent.

But, it’s relatively spendy.

 

Just pondering, I thought about silicone adhesive as a binder.

 

Come to think of it, the “RTV” in front of the silicone used in automotive applications stands for “Room Temperature Vulcanizing”.

 

I wonder if a thin solution of RTV Silicone would work as a binder?

 

It would be easy, inexpensive, cure fairly quick, would repel moisture & would have a passivity effect.

 

Edited March 13, 2011 by oldguy

[Peret]

As far as pressing goes, I think any pressure is safe - the books speak of military magnesium flares being pressed at ten tons psi and more. It's hammering with a mallet that's hazardous. You might want to make sure the compound is well compacted so that you don't have a hang-up give way at considerable pressure and give the same effect as a hammer blow

 

Any pressing of a long tube will be a slow SOB, since you need to press in increments and keep withdrawing the ram to add more compound.

[dagabu]

I crush Mg/Al on my press at 9000 PSI, never a problem, I think you should be safe as long as you dont have a shock or pressure sensitive comp that could make it pop. I suggest GE Silicone II if you want to try something. It is used already in a blue strobe comp so we know that it is compatible with pyro chems.

[oldguy]

Any pressing of a long tube will be a slow SOB, since you need to press in increments and keep withdrawing the ram to add more compound.

 

LOL, I figured that one out pressing the very first tube with my hydraulic press.

To much labor & time involved.

 

So, I am looking for something faster & inexpensive.

Good to hear pressure is not an issue.

Except the time/labor involved.

[oldguy]

I crush Mg/Al on my press at 9000 PSI, never a problem, I think you should be safe as long as you dont have a shock or pressure sensitive comp that could make it pop. I suggest GE Silicone II if you want to try something. It is used already in a blue strobe comp so we know that it is compatible with pyro chems.

 

9000 PSI.... Okay great.

Comp is not pressure or shock sensitive.

I was just worried about the Mg/Al in it.

 

GE silicone sounds good.

Off to the hardware store to get some & give it a whirl.

Edited March 13, 2011 by oldguy

[NightHawkInLight]

Why do you need a binder at all? If you're pressing the comp at these high pressures it's going to result in a solid grain. If the tube is sturdy it should protect it just fine, and the rubber coating that is on the examples of your flares I've seen should offer plenty of mechanical shock resistance to keep the grain from fracturing on hard impact. If you use a binder at all I have a hard time imagining anything besides a two part epoxy will yield a cure time shorter than multiple weeks when pressed into a tube. Even at high temperature you're talking about a very small hole on one end for all the moisture to escape out of, which quickly becomes impeded by the comp drying at the top causing a slower dry time exponentially as you precede down the tube.

[dagabu]

I forgot about that NHIL, the Glisionite should work as a binder as well as high pressure. I make pellets for my cannon from 2FA by pressing them with a comet pump. No water, no binder, just dry BP.

[Mumbles]

If your composition has shellac or red gum in it, they will also both act as binders at high pressures.

[oldguy]

Why do you need a binder at all? If you're pressing the comp at these high pressures it's going to result in a solid grain.

 

I don't want to hydraulic press the them at all.

 

It is time & labor intensive.

 

Hand loading-tamping or auger loading under a bit of pressure, it about 100 X faster.

 

Modern road safety flares are auger loaded, under slight pressure.

 

That makes the comp, as well as the tube solid.

 

A solid comp ignites, propagates & burns off better, with a binder.

 

Modern road safety flares don't really use a per se binder.

 

The slight loading pressure & tube hold them together.

 

But, modern road safety flares don't contain Al, Mg, or Mg/Al.

 

Because a hotter burn with reactive metals in the comp, increases the burn rate speed.

 

10 minute road safety flare, if reactive metals are included will burn out in about 2 minutes or less & cost 3X times as much.

 

As the metals are expensive, require passivation, extra labor & increased costs.

Edited March 14, 2011 by oldguy

[Stinger]

I myself use the following composition with MgAl in it which is very forgiving:

 

50g SrNO3

30g MgAl , 100 mesh

20g Parlon

 

I use 5ml of acetone, knead the composition thoroughly and rice it.

The mixture presses really really nice and emits a very deep, "eye-irritaing" red.

If you tap the tube with a wooden stick it sounds like porcelain, just try it out and see for yourself!

 

The flare becomes much brighter if coarse magnesium and sodiumnitrate is used.

[oldguy]

 

just try it out and see for yourself!

 

The flare becomes much brighter if coarse magnesium and sodium nitrate is used.

 

I did & you are on the money.

 

Why is it you don't see much sodium nitrate put to use in pyro.

Is it because its hydroscopic?

 

Once you find a local source, its very inexpensive.

[dagabu]

Yes, the comps never really dry in the summer in most places.

[oldguy]

Yes, the comps never really dry in the summer in most places.

 

LOL, they would dry in the NV desert in summer.

 

One of my sheet metal storage sheds gets about 145+ F inside on sunny summer days & zero RH.

That SOB about turns into a mild solar oven.

 

Sodium nitrate is in several of the new perchlorate free military flares.

 

But, they are bound with 2 part epoxy binders & oven cured.

 

On top of that the casing tubes are waterproof.

 

If it works for the military, seems like it would work for civilian use.

 

_______________

 

2008 MILITARY YELLOW FLARE PATENT EXAMPLE BELOW

 

1. A flare composition for producing a yellow flame, the composition comprising, by weight, a magnesium fuel within the range of approximately eighteen percent (18%) to approximately thirty percent (30%) of the composition, the magnesium fuel including particles sizes selected from the group consisting of granulation 15, granulation 17, granulation 18, and mixtures thereof, a magnesium-aluminum alloy within the range of approximately zero percent (0%) to approximately five percent (5%) of the composition, a sodium nitrate within the range of approximately eighteen percent (18%) to approximately thirty-eight percent (38%) of the composition, a barium nitrate within the range of approximately twenty-six percent (26%) to approximately thirty-six percent (36%) of the composition, a polyvinyl chloride within the range of approximately seven percent (7%) to approximately twelve percent (12%) of the composition, an asphaltum within the range of approximately zero percent (0%) to approximately five percent (5%) of the composition, and a two-part curable binder system within the range of approximately four percent (4%) to approximately seven point five percent (7.5%) of the composition, the binder system including within the range of approximately seventy percent (70%) to approximately eighty percent (80%) epoxy and within the range of approximately twenty percent (20%) to approximately thirty percent (30%) curing agent.

 

2. The composition of claim 1, wherein the magnesium fuel is approximately twenty percent (20%) of the composition.

 

3. The composition of claim 2, wherein the magnesium fuel includes mixtures of particle sizes.

 

4. The composition of claim 1, wherein the sodium nitrate is approximately thirty-seven percent (37%) of the composition.

 

5. The composition of claim 1, wherein the barium nitrate is approximately twenty-seven percent (27%) of the composition.

 

6. The composition of claim 1, wherein the polyvinyl chloride is approximately eleven percent (11%) of the composition.

 

7. The composition of claim 1, wherein the binder system is approximately five percent (5%) of the composition.

 

8. The composition of claim 1, wherein the epoxy is approximately three point five percent (3.5%) of the composition.

 

9. The composition of claim 1, wherein the curing agent is approximately one point five percent (1.5%) of the composition.

 

_____________________

 

EDIT TO ADD

 

 

I used a Gilsonite solution as a binder on these tubes.

 

That is what you see bleeding through the tube wall as they dry.

 

 

Burn off test of 1 from the same batch of dried tubes.

 

I also figured out an easy way to waterproof the tube, once they are dry as a rock.

 

Heat shrink tubing does the trick.

 

Since they are capped on both ends with a plastic cap.

 

That makes them about as waterproof as you can get quickly & inexpensively.

 

Object of using sodium nitrate is its easy to get & very inexpensive.

 

Since the tube can be dried, then waterproofed.

 

That would cut the per unit cost down considerably.

 

On top of that sodium nitrate appears very effective for my purpose.

Edited March 20, 2011 by oldguy