OR BUILT UP MICA
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Mica or Mica products are employed in electrical engineering already
since the turn of the century. Micanite is the name given to sheet material
which is made up of fine mica lamellae, called "splittings",
bonded together by a variety of bonding agents such as Shellac, epoxy,
alkyd or silicone, in order to obtain particular characteristics for
specific uses. Variations can be made in the method of manufacture,
the types of Mica, and the type of quantity of bonding material used
to form thick or thin, stiff or flexible products in the form of sheets,
webs or ribbons and also moulded articles.
Mica Sheets are made of natural muscovite mica splittings bonded
with a minimum amount of resins in compact, dense and rigid
flat plates by means of multiple high temperature pressing primarily
for use as insulation between copper segments or bars of commutators
used in traction motors as well as other electric motors and
turbo-generators. The resin is cured for several hours at high
temperature to preclude any ozzing or slippage of the mica.
The natural cohesive forces between the mica platelets combined
with the bonding strength of the rigid thermosetting binder
makes these plates adequately resistant to high heat and pressure
encountered in the commutators. These plates have high dielectric
strength, high thermal stability, good voltage endurance and
excellent mechanical and electrical properties. Besides they
have extremely low compressibility as is essential in maintaining
the commutator's dimensional stability under large centrifugal
stresses in operation. Their other properties are smooth surfaces,
uniform thickness, great resistance to crushing and excellent
mechinability. Commutator mica sheets bonded with shellac resins
provides an excellent overall properties. Epoxy and alkyd yield
dimensional stability with ability to withstand extreme compression
MOULDING MICA SHEETS
Mica sheets are produced from natural muscovite mica splittings
bonded with a thermoplastic resins either shellac, epoxy or
alkyd-vinyl by applying adequate heat and pressure. The amount
of bond content range from 18% to 22%
depending on type of product demanded. The relatively high amount
of bond facilitate the mica to slip relative to each other during
the moulding process as necessary in assuming the desired contour.
These sheets are rigid at room temperature but soften when heated
at temperature between 100oC to 140oC and could easily be moulded
into practically any shape upon the application of either hot
or cold process. With further cure, the sheets form into rigid
well bonded structure retaining the shape of their moulded forms.
Moulding sheets bonded with shellac provides optimum mouldability
having an excellent overall properties and have been traditionally
most popular, while epoxy or alkyd-vinyl bonded sheets offer
toughness and durability under severe mechanical stress applications.
MICA SHEETS are produced from natural muscovite mica splittings
bonded with synthetic, epoxy or silicone resins suitable for
thermal class 'B', 'F', and 'H' into a rigis sheets under high
heat, and pressure conforming to IEC Standards 371.3.3.
These sheets are hard and dense and could readily be punched
to any specified shape and designs providing and excellent overall
properties. They have high dielectric strength, flexural strength,
thermal stability, low moisture absorption and good arc resistance
properties. They are superior product in intensity,waterproof
ability, incombustibility and electrical insulating properties.
Mica Sheets are produced from natural Muscovite mica splittings
bonded with polyester or silicone resins. The controlled low
binder content assures a throughly cured product in which the
binder will not ooze or flow from the mica structure.
They possess excellent flexibility and adhesiveness to permit
winding or wrapping of the sheets at room temperature without
heating. They can be formed or bent readily to any shape and
will not become brittle and stiff. They can be applied to unusual
configuration without tear. They remain flexible at room temperature,
rigid at high temperature, develops increased tenacity and are
fully oil resistant. Besides they do not react with copper.
They have high moisture and heat resistance, high dielectric
strength, excellent chemical resistance and electrical insulating
properties. They have long shelf life and thus eliminates inventory
problems normally encountered with conventional electrical insulating