Tongue and groove ceramic segments without mortar for coreless induction furnaces from 650 to 15,000 lb, in air or vacuum.
Large linings crack because they cannot move.
InterLok gives every segment its own room to grow.
A segmented crucible lining reduces thermal stress by splitting the lining into interlocking segments with designed expansion gaps, so the lining can grow and shrink with each heat instead of building up stress in one rigid shell. InterLok uses precast tongue and groove ceramic segments, set without mortar and held by a spring loaded hold down system, for coreless induction furnaces from 650 to 15,000 lb steel capacity in air or vacuum. In finite element comparisons of rammed, mortared and segmented linings, the segmented design showed clearly lower stresses.
In furnaces above roughly 500 kg, thermal stress rather than chemical attack decides how long the lining lasts. Every heat expands the lining, every cool down shrinks it again.
The movement is not small. In a 3 ton lining of alumina or magnesia, the height grows by up to 7 mm at temperature. A rammed lining or a monolithic crucible has nowhere to put that growth, so it turns into stress, and stress turns into cracks, spalling and metal penetration.
Magnesia brick has a second problem under vacuum: it releases magnesium into the melt.
The same furnace, two ways of lining it. The difference is where the expansion goes.
A lining that is allowed to move does not have to crack to make room for itself.
InterLok comes in eleven standard sizes. Side brick height and the number of courses are adjusted to the furnace, so the standard sizes cover most coreless furnaces in this range.
| Steel capacity | Outside diameter | Inside diameter | Bottom | Wall | Height |
|---|---|---|---|---|---|
| 650 lb (295 kg) | 16 in (406 mm) | 13.5 in (343 mm) | 1.75 in | 1.25 in | 27.25 in (692 mm) |
| 15,000 lb (6,804 kg) | 44 in (1,118 mm) | 39.5 in (1,003 mm) | 4.5 in | 2.25 in | 73.75 in (1,873 mm) |
Spouts and spout extensions are cast into the lining. For bottom pour furnaces, the segments carry the through holes for nozzle and stopper rod.
The backup ram behind the segments matters as much as the segments. ALRAM 4041 backup ram was designed for linings of this class.
Four furnaces from earlier Blasch installations, each compared with the lining it replaced.
12,000 lb furnace
Alloys 625, 713 and 718 at 1,590 to 1,700 °C, against a rammed lining. Rework from inclusions fell by half, capacity rose by 5%, and the lining paid back after about 15 heats.
6,000 lb furnace
Nickel and cobalt alloys under vacuum, against magnesia brick that released magnesium into the melt. The lining also tolerated weekend shutdowns.
2,000 lb furnace
Ni, Co, Cr, Al and Y alloys at 1,670 to 1,780 °C, against a monolithic crucible. Installation took 30 to 40% longer, payback came at about 10 heats.
1,500 lb furnace
Aluminum metal matrix composites with up to 20% SiC or alumina at 770 °C, against a rammed lining. The material cost about twice as much and broke even at 75 to 100 heats.
InterLok is part of the crucible and melt products range.
High alumina crucibles in four grades for furnaces up to 4,500 lb.
No. The segments interlock without mortar and are fired before installation, so no wash heats are needed.
Yes. It is used in air and vacuum coreless induction furnaces, including bottom pour configurations.
Standard sizes run from 650 lb to 15,000 lb steel capacity. Height and course count are adapted to each furnace.
A spring loaded hold down system keeps the segments together while it lets the lining grow and contract through each heat.
Send the furnace capacity, the coil dimensions and the alloys you melt. A Blasch engineer sizes an InterLok lining for your furnace.
