What is GLASS BONDED MICA (GBM)?

GLASS BONDED MICA (GBM) a ceramoplastic, is a bridge between epoxy, frp and ceramic – combining the best properties of these materials.

This is a unique product wherein mica (which is a proven high reliability electrical insulating material) is the principal constituent and glass which is an inorganic material is used as a binder for mica.

Their bonding is done at a temperature of approximately 800 degrees Celcius under high pressure.

GBM is a High Voltage, High Tensile, and High Temperature insulating material.

The products are marketed under various product names as Brush Holder Support Insulator, Terminal Support Insulator, Insulating Rod, and Arcing Chamber/Arc Chute etc.

Properties

● Completely inorganic – does not burn
● High dielectric strength & arc resistance
● Low thermal conductivity
● Withstands thermal cycling
● Impervious to moisture, oils, and gases
● Can be machined: drilled, tapped or threaded with carbide tools
● Ability to be silicone or PTFE coated.
● Used for Varied Operating temperatures of upto 400°C
● Metal inserts can be embeded: Steel, non ferrous or SS.
● Not hazardous unlike asbestos based insulating materials

Applications

The unique combination of the above properties make GBM the first choice for insulators in the traction field and for other areas requiring high reliability.

Insulators in Traction
High Voltage applications
Bus bar supports
Stand off insulators

Other areas requiring a mechanically, thermally stable and ability to work in harsh environments.

Our GBM Sheets meet or exceed all test parameters, including arc resistance, resistance to tracking and inflammability test. The Advantage of the material is it is Inorganic & Non-Inflammable material. The most important characteristic of this material is it is a Non-Asbestos material.

One of the recent products, which we have developed, is the Arcing Chamber Assembly for Tap Changers. We are approved by RDSO we have been supplying this item to the Zonal Railways.

Glass Bonded Mica Sheet – Technical Data 
Properties Unit Value
Density g/cc 2.65
Tensile Strength MPa 30
Shear Strength MPa 50
Flexural Strength Mpa 110
Compressive Strength MPa 250
Compression Yield % 1