Glass extrusion

[eranglr]

Hi.

I've got two questions:

1. how does a glass rods are made? is it by extruding it?

2. Is it possible to extrude glass rod (3mm diameter, boro) through a heated nozzle with a 1mm width 'hole'.

Meaning - top of the nozzle is 3mm, bottom - 1mm width, nozzle will be heated to the glass temperature (thought about a ceramic nozzle,
other ideas?).

Thanks!
Eran

[Valerie Adams]

You can pull cane from a vitrograph set up. Different sized holes will result in different thicknesses of canes.

[eranglr]

Didn't knew about vitrograph (checked some youtube movies, nice!).

Thing is - in this way, the glass is pulled, and I want to push it through a die/nozzle (without
any pulling help).

If i'll make a ceramic nozzle, and heat it up with a torch?

[ejgiebel]

While you might be able to do something like this, in my limited vitrograph experience, you'd need a much bigger hole. This is like trying to pour molasses through a 1 mm hole. It may work, but you’ll never wait around to find out.

I pulled rods and strings, and I had a ¾ inch hole in the bottom of the pot, and I was hard pressed to get anything more than about 6mm out at 1500 degrees F. I’m thinking you’ll need force one way or the other – either pushing it through the hole, or pulling it out the hole. While you might get something to flow, you’ll be horribly bored by the whole process after about 3 inches.

Ed

[Alexis Dinno]

1. how does a glass rods are made? is it by extruding it?

3mm may also be possible using the same kind of lamp-working technique used to produce stringers.

Can you explain why you believe you need to use a die?

[Tom Fuhrman]

glass tubing and rod is always pulled not pushed thru dies. furnace needs to be about 1950-2300 depending on type of glass. Boro will probably need to be even hotter. flow needs to be continous once it starts.