Resin Impregnation

Resin impregnation fills the porosity of a part with a resin to create a pressure-tight part for hydraulic applications which can withstand several thousand psi, to improve machine ability, or to allow electroplating. The parts are placed in a mesh basket and loaded into a vacuum tank. This is then submerged in a bath of Anaerobic resin. A vacuum is pulled to remove all air from the porosity of the parts. This vacuum is released to and the tank is pressurised, causing the resin to be drawn into the porosity of the parts. Parts that typically undergo resin impregnation include hydraulic fittings for pressure tightness and plating, covers and plated for pressure tightness, as well as machined components.

    The previous method of sealing parts was a furnace treatment, which formed a hard oxide layer on the internal and external surfaces of a part, filling the porosity. Most machining operations were performed prior to sealing the part because the hard oxide layer adversely affected mach inability. Residue left by traditional cutting fluids tended to inhibit the formation of an oxide layer. With resin impregnation, conventional cutting fluids can be used because the furnace treatment is eliminated resulting in improved mach inability. These fluids efficiently remove heat from the cutting tool, extending the tool life. Machining a porous part effectively creates a continuous interrupted cut.

 Each time the tool impacts metal after passing through a pore, it may chip and become dull. Resin impregnation reduces that effect and may also provide added lubrication to the cutting tool. Before resin impregnation, many parts were mechanically plated. Resin impregnation allows the use of electroplating.

EPOXY RESINS:

                        Epoxy resins are poly ethers derived from Epi-Chloro Hydrin and Bis-Phenol monomers through condensation polymerization process. These resins are product of alkaline condensed of Epi-Chloro Hydrin and product of alkaline condensed of Epi-Chloro Hydrin and Poly-Hydric compounds.

In Epoxy Resins cross-linking is produced by cure reactions. The liquid polymer has reactive functional group like oil etc, otherwise vacuum as pre polymer. The pre polymer of epoxy resins allowed to react curing agents of low inductor weights such as poly-amines, poly-amides, poly-sulphides, phenol, urea, formaldehyde, acids anhydrides etc, to produce the three dimensional cross linked structures.

            Hence epoxy resins exhibit outstanding toughness, chemical inertness and excellent mechanical and thermal shock resistance. They also possess good adhesion property. Epoxy resins can be used continuously up to 300°F, but with special additions, the capability can be increased up to a temperature of 500°F.

Epoxy resins are made use as an efficient coating material. This includes coating of tanks containing chemicals, coating for corrosion and abrasion resistant containers. Epoxy resins are made up of as attractive corrosion and wear resistant floor ware finishes.

These are also used as industrial flooring material. They are also used as highways Surfacing and patching material. Moulding compounds of epoxy resins such as pipe fitting electrical components bobbins for coil winding and components of tooling industrial finds greater application in industries.

            The epoxy resins similar to polyester resins can be laminated and Fiber Reinforced (FPR) and used in glass fiber boats, lightweight helicopters and aero planes parts.

            In the modern electronic industry, the application of epoxy resins is great. Potting and encapsulation (coating with plastic resin) is used for electronic parts. Most of the printed circuits bodies are made of laminated epoxy resin which is light but strong and tough.

PROPERTIES:

1)      Epoxy resins have good mechanical strength less shrinkage and excellent dimensional stable after casting.

2)      Chemical resistance is high.

3)      Good adhesion to metals.

4)      To impact hardness certain organic acid anhydrides and alphabetic amines are mixed.

APPLICATIONS:

           

1)      They are used in the manufacture of laminated insulating boards.

2)      Dimensional stability prevents crack formation in castings.

3)      They are also used as insulating varnishes.

8.1        INSULATING MATERIAL FOR LAMINATIONS: -

            The core stacks in modem machines are subjected to high pressers during assembly and there fore to avoid metal-to-metal contact, laminations must be well insulated. The main requirements of good lamination insulation are homogeneously in thin layers toughness and high receptivity.

We use varnish as insulating material for laminations.

8.2 VARNISH

            This is most effective type of insulation now available. It makes the laminations nest proofs and is not affected by the temperature produced in electrical machines varnish is usually applied to both sides of lamination to a thickness of about 0.006mm. On plates of 0.35mm thickness varnish gives a stacking factor about 0.95.In order to achieve good insulation properties the following processes are in BHEL.

• THERMOPLASTIC PROCESS OF INSULATION
• THERMOSETTING PROCESS OF INSULATION

   BHEL is practicing only thermosetting process of insulation so

  Thermosetting types of insulation are of two types:

    RESIN RICH SYSTEM OF INSULATION

                  RESIN POOR SYSTEM OF INSULATION