The term epoxy is derived from ‘epoxide’ which is the technical name describing a specific arrangement of carbon and hydrogen atoms (cycl-CH2OCH) that terminate their molecules.  It is the placement of the oxygen along epoxy's carbon chain and the epoxide groups at the ends of the carbon chain that gives epoxy its useful properties, namely that epoxies are tough, extremely weather-resistant and do not shrink as they cure (dry). 

Since its discovery, epoxy resins has had numerous applications.  It has been used to create chemical resistant pipes and pumps, pottery molds, impellers, press and vacuum forming tools, patterns and core boxes, molds for RIM, laminates for aircraft and automobile components, fiber wound products and more importantly for our purposes, since the 1950's when it was discovered that epoxy had excellent electrical insulation properties and was greatly chemical resistant, electrical parts such as relays and coils and transformers have been created with epoxy.
    There exits many types of epoxy resins, namely:
  • Bisphenol A: which is the resin most widely used for manufacturing of castings, moldings, laminates and filament composites
  • Novolacs: an epoxy resin with higher heat and chemical resistance and stiffness than Bisphenol A epoxy resin.  Most commonly used to create rigid castings, moldings and laminates.
  • Brominated Epoxies:  which are the most 'fire resistant' of the epoxy resins.
  • Glycidyls:  Epoxy resin with the most flexibility. 
  • Cycloaliphatics:  Epoxy resin most suitable for outdoor use because of its good weathering resistance.  Although cycloaliphatic epoxy resin has great mechanical strengh, its rigid structure can result in brittleness.

    At E.B. Electrocast our epoxy insulators are made with epoxy resin because epoxy resin is non-tracking, self-scoring, non-weathering  and resistant to repetitive heating to 120F and cooling to -40F.  Thus, epoxy has perfect electrical and mechanical properties for the manufacturing of bushings and insulators. 

    Furthermore, epoxy resin insulators and bushings allow metal conductors and other types of metal inserts to be included as an integral part of the casting.  In addition, flanges, holes and cross sections can be molded as part of the insulator or bushings design. 

    E.B. Electrocast Inc.’s epoxy resin is created with silica under carefully controlled conditions of pressure and temperature.  The silica mixture is then poured into aluminum molds, designed and produced by E.B. Electrocast Inc., to assure a strong bond between epoxy and metal parts.  It is important to note that the relatively low viscosity of the mixture permits the formation of intricate designs that are not possible with porcelain insulators.   Finished parts are then oven-cured to achieve specified mechanical properties and subsequently cleaned, inspected and tested to make sure they are of the highest quality before being shipped to our customers.

Epoxy vs. Polyester Insulators
    Epoxy has greater strength than polyester, better wear resistance and higher resistance to cracking when encapsulating metal components.  Furthermore, epoxy resin insulators and bushings have better chemical resistance (i.e. resistance to alkalis and solvents) than do polyester insulators and bushings.  Epoxy resin insulators also have high resistance, good dialectic strength and consequently offer better electrical insulation than polyester.  Additional advantages of epoxy over polyester when it comes to making insulators and bushings is that epoxy has low curing shrinkage and excellent adhesion to metal, wood and other polar substrates.

Epoxy vs. Silicon Rubber and EPR
    Silicon rubber and EPR insulators have a central load-bearing fiberglass core for mechanical functions and a polymeric housing for electrical functions.  In contrast, epoxy resin insulators use the same material to perform both their electrical and mechanical functions thus minimizing the number of interfaces which is much desirable.

Epoxy vs. Porcelain (Fired-Clay)
    In comparison with porcelain insulators, epoxy resin insulators have superior strength.  Furthermore they weigh approximately half of what a comparable porcelain insulator weighs.  Epoxy resin also allows much more manufacturing flexibility than does porcelain because it is not brittle and consequently can be molded into intricate shapes and designs and can be made more compact than comparable porcelain insulators and bushings. 

    Furthermore, epoxy resin insulators are non-tracking, self-scoring and non-weathering, thus they will perform satisfactorily in all types of environments, even highly contaminated areas.  Epoxy resin is also resistant to ultraviolet rays and has a greater tolerance to physical impact than porcelain, and consequently will not shatter due to thermal shock.  In addition, insulators made with epoxy resin have a greater dry arcing (strike) distance than porcelain insulators because they are end free whereas porcelain insulators have metal caps.  Epoxy resin insulators also resist high-power arcs without damage and without need for post-arc ‘cleanup’.  Yet most importantly, epoxy resin insulators cost less to fabricate and to maintain than porcelain insulators.

Epoxy Mouldings

Epoxy Mixing Machine

C/T & P/T such as APG Machine
APG Machine

Epoxy Mixing Machine

Epoxy Mixing Machine

Epoxy Moulding PT
Epoxy Moulding PT

Epoxy Moulding Ct
Epoxy Moulding Ct

Epoxy Resin Casting
Epoxy Resin Casting

APG Machine with Hydraulic power Pack
APG Machine with Hydraulic power Pack


  1. Papti Insulators and spacers are great layer pf protection from electrical current.Plastics and woods are great example of these!


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