Other insulation material for induction furnaces
Other insulation material for induction furnaces
In addition to coil isolation materials, other insulating materials are used for electrical and heat isolation in other parts of the induction furnace. Here, while introducing these materials and their applications, thorough information is provided about their characteristics.
Isolation pad:
Isolation pad is a set of isolation layers placed between coil and yokes of induction furnace to isolate against each other. Araz Trans Co. offers various types of isolation pads for particular applications to the costumers.
Below pictures present various compounds and layers used in isolation pads offered by our company.
Jointing Plate : Aramid fiber
with nitrile rubber binder
NMN sheet : Nomex +
Mylar + Nomex
Rigid Muscovite/
Phlogopite Mica sheet
ArazTrans company’s innovative design for
insulation pads, which is mentioned in the
chapter related to “Induction Furnace Yoke”.
Silicon rubber tubes reinforced
with fiberglass strips
PTFE sheet
Fiberglass sheet
PTFE sheet
Refractory blocks:
Refractory blocks are used as isolator between coil and furnace structure from top and bottom (called upper and lower rings) casted from fibered 50% Alumina in various shapes and sizes. To solidify the block against fragility, metallic materials are added to the batch while casting. Refractory blocks are used in both unit and sectional form. The biggest advantage of the sectional blocks, is to offer empty space between blocks to avoid cracks against expansion duo to furnace heat.
sign | item | Common gender |
1 | Top ring | Alumina 50% |
2 | furnace coil | Messi’s special sections |
3 | Coil wall mass (Grout coil or coil concrete) |
Alumina 95% |
4 | Lower ring | Alumina 50% |
5 | Spacer layer | A roll of mica base compounds |
6 | Refractory Lining | Silica mass or spinel |
Refractory spacer:
Refractory spacer is used to separate grout coil from the furnace lining. The main responsibility of these spacers is to prevent the melt heat and leaked melt from coil. Moreover, special type of spacers are used as part of the alarm system. Spacers are commonly in the form of rolled flexible Mika in different grades. The upcoming table summarizes various grades of rolled Mika-based spacers offered by Araz Trans Co..
If the spacer from second row is applied, relative melt leak alarm system can be exploited. To do so, after proper furnace reconfiguration and resistance measurement apparatus provided by our company, the instantaneous resistance of the mid spacer layer (non-magnetic steel net) and earthing system(where the melt is connected to the earthing system via an antenna) is measured and monitored to diagnose resistance decrement caused by gradually penetrating melt, approaching mid spacer layer. At certain predefined drop of resistance, previously recognized by the protection system, the alarm goes off and at urgent conditions drops electric supply of the furnace down. This an efficient and low-expense approach for melt leak alarm for furnace.
Schematic figure |
explanation | Dimensions | Technical specifications |
layers |
Category | ||||
Roll length (m) |
Roll width (mm) |
thickness (mm) | Heat transfer coefficient (°C) |
Minimum tolerable temperature (W/m/°C) |
Electrical strength (KV/mm) | ||||
 |
– |
Max 2.4 |
1000 |
0.1-0.6 |
0.20 |
1000 |
18< | Flexible phlogopite mica |
1 |
| This item is used in furnaces equipped with a special melting leakage system |
Max 2.4 |
1000 |
0.9±0.1 |
0.25 |
1000 |
23< |
Flexible phlogopite mica, non-magnetic steel mesh, flexible phlogopite mica |
2 |
|
– |
Max 300 |
500 یا 1000 |
0.14-0.49 |
0.35 |
Mus=1000 ph=1200 |
Mus>25 ph>23 | Phlogopite mica/ flexible muscovite glass fibers |
3 |
|
|
|
500 یا 1000 |
|
|
|
| Phlogopite mica/flexible muscovite glass fibers Flexible phlogopite/muscovite mica |
|
|
– |
Max 100 |
1000 |
0.40 |
0.35 |
1200 |
>23 | Non woven fiberglass Flexible phlogopite mica glass fibers |
5 |
|
|
|
|
|
|
|
| Non woven fiberglass Flexible phlogopite mica glass fibers Non woven fiberglass |
|
|
– |
12.5 20 25 |
|
|
|
|
| glass fibers Flexible phlogopite/ muscovite mica Calcium silicate |
|
|
|
20 25 |
|
|
|
|
| Flexible phlogopite/ muscovite mica glass fibers Calcium silicate |
|
|
| 10 15 20 25 |
|
|
|
|
|
|
|
| This item is used to prevent the penetration of molten zinc towards the coil |
order |
2.4 |
0.10 |
1100 |
| glass fibers Flexible fine-grained phlogopite mica Calcium silicate Aluminum alloy |
10 | |
|
– |
20 |
1000 |
0.65±0.05 |
0.10 |
900 |
| Flexible fine-grained phlogopite mica Non woven fiberglass |
11 |
