PDA

View Full Version : Quality and lifetime of wire elements


Tim Elias
05-28-2012, 08:32 PM
We use a home built wire melter which uses elements from Aims 1715C for a 80 pound crucible. We're using a Watlow controller: DIN-A-MITE (Solid state power controller) with 2 elements running plus a back-up one.
It ran 2170 for 5 weeks, it went on back-up, then ran for 1-1/2 weeks. Both old elements are now blown.
Can any of you recommend longer lasting system? Different elements (cheaper...) ???

Waiting to hear with appreciation, M-Chantal, Blown Away (haha) Glass

Mike Hanson
05-29-2012, 12:35 AM
You could use this supplier:

http://www.duralite.com/store/scripts/prodView.asp?idproduct=108

If you are running two elements with a backup use DURA 005680

If you are running three use DURA 005679

make sure to order a spare or two, they are less likely to burn out that way...

Richard Huntrods
05-29-2012, 01:11 AM
What is the watt loading for your furnace? If it's under-powered (wattage wise) then you will be hurting any element you install trying to keep things hot.

There are lots of other threads discussing stretch, installation, keeping elements away from glass fumes etc.

Also, how fast you ramp up, what you melt... wheter cullet or batch and what type of cullet. How hot you melt and for how long... it all factors into the element life equations. That and the color of your tie on tuesdays after a full moon, among many other mystic factors.

Cheers,

-R

Pete VanderLaan
05-29-2012, 06:54 AM
It seems to me that holding at 2170 is a lot of stress in itself. That would be really hot glass to work with.

Did you check your connections after you first fired up? Connections get loose when they are turned on, then, unchecked, they arc. Did they fail near the split bolt or was it inside the kiln?

Most of the wire in this country comes from Kanthal. There is a French source which ostensibly is excellent stuff. Kanthal has been known to have bad batches on fairly rare occasions but I think the operator application is the more likely source of the problem here. Both Mike and Richard are right respectively. Duralite is a good source for both elements and wire and how you hook up the kiln is actually critical to success. I think you need to ask and answer some questions about your process but I doubt that the element itself is the problem unless you used something totally inappropriate to your kiln's needs. You don't even say what gauge wire you used.

Tom Fuhrman
05-29-2012, 09:33 AM
For an 80lb. unit which is what I run as well, I use 3 elements and never go beyond 2150 and most of the time I melt cullet and melt it at 2110 or below and get good glass heating over an evening. I also think you may need more insulation in your unit. I get 9+ months from a set of elements from AIM and sometimes longer.
Melting for long periods at 2170 seems very high even if you are melting SP batch. I think you are probably underpowered with only 2 elements. I've been going since Nov. with the new French wire and so far it has maintained heating quality very well.
Most Wire melters just aren't designed to maintain temps above 2150 for any duration. That's like trying to run a VW engine at 140 mph for weeks at a time. It can be done if it is geared properly and the wire melter can be the same way if you run it properly and have the right type of controls.

Dave Bross
05-29-2012, 10:01 AM
Somewhere here there's a link to Jordan's element calculator, or he may pop up and post it.
The only link I found in a quick search was dead. I'm pretty sure there's a live one here.

I selected these from a search here on "watt loading" which is critical to understand for wire melters. I couldn't find the actual math for calculating watt loading but it's here somewhere. Easier to just use someones calculator for that anyway:

http://talk.craftweb.com/showpost.php?p=71187&postcount=10

http://talk.craftweb.com/showpost.php?p=86815&postcount=5

http://talk.craftweb.com/showpost.php?p=86824&postcount=7

There's lots more info to be had here via search.

I won't rehash using variacs for temp control because you're using the digital equivalent.

I do wonder if the dropped voltage from using a variac is helping with the extended element life. It's well proven that incandescent 120v bulbs run at 110 volts or less will last almost forever as opposed to the 120v. Who remembers the little wafer resistors they sold in the 60s/70s to put in the sockets under the bulb?

Scott Novota
05-29-2012, 04:08 PM
Tim,


You are closing off the elements from the pot right? If I remember correctly 5 to 6 weeks would be about the life span of elements if exposed to the glass gassing off and getting to the elements.


I only ask because I did not see you state that in the post.

Tim Elias
05-29-2012, 06:16 PM
We are going to open furnace tomorrow and be able to see the cause of early failure.

Pete VanderLaan
05-29-2012, 06:18 PM
Great questions Scott. Are these elements being exposed to spectrum nuggets? ( Which I cannot imagine holding at 2170F)

Tim Elias
05-29-2012, 06:30 PM
Going from a Stadelman type furnace for plus 13 years to the wire melter is proving to be huge learning curve as we also now use Spectrum pellets (instead of Spruce Pine). All your info is amazingly helpful and will investigate some different avenues as in:- 3 elements on instead of 2
-french wire? where to get them seems a bit of a concern...
-love the part about insulating more
-getting used to working with a lower temp. glass than previous (2170+) seems doable
-the elements are closed off pot but gassing off damages anyway???
.... many considerations and thank you for info. Will be back once furnace opens (tomorrow) and brain annealed after technical overload...
MChantal

Scott Novota
05-29-2012, 07:01 PM
No sorry for the confusion, I was asking if they were sealed away from any gas from the melting glass. If they are the question is answered.

Cecil McKenzie
05-29-2012, 07:57 PM
Did you check the elements for continuity? It seems weird that both elements went bad at the same time. Are you sure the relay isn't stuck in the open position?

Tim Elias
05-29-2012, 11:42 PM
spectrum at 2170. started at 2140 but chantal needed hotter glass, i made a cap with ramable and a frax gasket. we will see tomorrow if the fumes got to the elements.does anyone use spruce batch in a wire melter? thx.

Dave Bross
05-30-2012, 06:11 AM
Many use SP in wire melters.

It has lots of lithium so it will melt at very low temps. if you have the time to wait it out.

Expansion changes a bit if you do that.

I've heard stories of loading up the furnace with SP and leaving it at 2000. It takes days to fine that way though.

With batch (SP) the only thing you need to go over 2170 for is to get the antimony to switch valence and eat the bubbles. You can do that for just long enough to be sure the middle of the melt has hit 2170 and then back down.

One more tech question.

Your thermocouple is sticking out into the melt chamber?

If not, you're running a lot hotter than you think.

Pete VanderLaan
05-30-2012, 06:57 AM
spectrum at 2170. started at 2140 but chantal needed hotter glass,
********
This is what I call "the no free lunch" syndrome.

Tim Elias
05-30-2012, 05:15 PM
sounds like we do not have the only wire melter.tim here......chantal bought an aims 1715 80 lb melter from a lampworker 6 years ago as a way to help her do short stints of production. i also built her a 12 inch glory with pine ridge ribbon burner. it worked okay, but was flimsy , a poor lid setup, and controller.I tried to improve on it, decided to build same idea w bricks on the flat and 2 inches frax 3 years ago. so its better but after looking over the responses from you all I have a slightly better one. Chantal will need to be hot for july. We will run cooler till the spectrum is gone and go back to spruce (YAY) and insulate more. I will get some elements from duralite. Any more info on the french wire will be great. This has tought me a lot to be grateful for the 17 years we got with our moly 200 lb. Thanks for all the past and future help. As i need to not own a glass shop any more, Chantal will be using your sage advice to help her run the studio. If all goes well I will be the old guy who just get to play with the glass......tim

Tim Elias
05-30-2012, 05:22 PM
I didn't read or check spelling. And to clarify, on trying to build a better mousetrap, i have built a slightly better one than the aims 1715. yay

Pete VanderLaan
05-30-2012, 06:29 PM
I think the JenKen is the best of them but don't interpret that as an endorsement. They are all underinsulated. You get what you pay for. It lets you make glass for a marginal investment