<< Pages [1] [2] >>

Laminated 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.


Commutator 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 stress.


Hot-Moulding 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.


HEATER 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.


Flexible 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 products.



Untitled Document
Untitled Document