How a fired ceramic loop ended the zinc penetration that cut inductor campaigns in a leaded brass furnace.
Zinc vapor had cut the inductor lining life in a leaded brass furnace by up to 90%.
A one piece fired ceramic loop brought the campaigns back
In a brass foundry with four 10,000 lb channel furnaces, a CeraLoop inductor lining of fired high purity alumina ran for about twice the tonnage of the castable linings before it and was still intact when the inductor was pulled. The second loop, installed in October 2019, stayed in service for 300% of the previous campaign length, according to the case study Allied Mineral Products published in October 2020.
The foundry makes products for water works, high pressure gas valves for utilities, water pumps, plumbing and industrial valves. It melts in four channel furnaces of 10,000 lb, each with a 500 kW twin loop inductor.
Two alloys run through the shop: C89833, a lead free brass containing bismuth, and C83600, a traditional leaded brass. Most production moved to the lead free grade, so the leaded brass furnaces now sit in long holding periods between a few shifts of high volume melting each week.
That pattern let zinc and zinc vapor penetrate the inductor lining. The refractory saturated, wore fast, and lining life on leaded brass fell by up to 90%.
Four different castables and dry vibratables failed the same way in this furnace, so the fix had to change how the channel is made, not which mix fills it.
The inductor was traditionally cast in a fused alumina, cement bonded castable around a wooden channel form, which was burned out with a resistance wire before the inductor went on the furnace. The foundry then trialed:
CeraLoop is a one piece, fully fired ceramic insert with very low porosity that forms the channel itself. The refractory behind it only backs it up. The foundry chose Procaster-C, a high purity alumina based ceramic, because alumina linings had served it well before. The material resists wetting by molten brass and handles thermal shock better than the standard lining.
| Loop | Installed | Backup | Result |
|---|---|---|---|
| First loop | March 2019, ran until August 2019 | fused alumina dry vibratable | about twice the tonnage of the previous linings, intact at inspection |
| Second loop | October 2019 | castable, same as the upper case | 300% of the campaign length |
More loops were made for this inductor and for others in the same foundry.
A fired loop needs no form burnout and no wash heat, and the furnace can start on any alloy. Fewer inductor changes mean fewer rebuilds of a 500 kW inductor and fewer hours with a furnace out of the melt schedule.
The same lining principle applies to other zinc bearing alloys.
Precast, fired loops for single, double and slanted inductor channels in copper, brass, zinc and aluminum.
A second CeraLoop case in channel furnaces melting aluminum zinc alloy.
Crucibles, linings and flow control parts for foundries and melt shops.
CeraLoop is made by Blasch and distributed by Allied Mineral Products, which also supplies the backup materials used in this foundry.
No. The fired loop forms the metal channel. A dry vibratable or castable fills the space between the loop and the inductor box.
The case study compares campaigns with the linings used before: about twice the tonnage for the first loop and 300% of the campaign length for the second. It does not state absolute tons.
Blasch makes loops in ultra high alumina and silicon carbide grades for copper, brass, aluminum, zinc, galvalume and iron. The grade is chosen for the alloy.
Tell us the inductor type, the alloys you run and how long the furnace holds between melts. A Blasch engineer checks whether a fired loop fits your inductor box.
