ECR Glass Fiber Rod: Manufacturing, Properties and Type Test:
E-Glass: “E Glass” refers to a type of glass fiber that is commonly used as reinforcement in composite materials. The “E” stands for electrical grade, but it can also be interpreted as “E-Glass” or “electrical glass.”
It has with good water-resistance, insulation and high mechanical strength. To simplify E-glass production, manufacturers add B2O3 and fluorine in the glass batch. During the process, particles with B2O3 & volatile fluorine get released into the atmosphere.
E-CR glass (E-Glass Corrosion Resistant): The main difference between E and E-CR glass is the elimination of boron oxide (B2O3) from the base formulation.
Basic Raw Materials: For making of FRP Rods we need Few material as follows:
1. ECR Glass Fibre Rovings
2. Resin
3. Hardener
4. Accelerator
5. Releasing Agent
Types of Fibre Glass
1.E Glass (Electrical Glass)
2. S Glass (High Strength Glass)
3. C Glass (Chemical Glass)
4. A Glass (Alkali Glass)
5. AR Glass (Alkali Resistant Glass)
Manufacturing Process of FRP (Fiber Reinforced Plastic) Rod:
The manufacturing process of Fiber Reinforced Plastic (FRP) rods for electrical insulators is a sophisticated process that requires careful control of materials, environmental conditions, and production techniques to ensure high-quality products with excellent mechanical and electrical properties.
Raw Material Preparation: Typically, an epoxy resin, Hardener, Accelerator and Releasing Agent is mix together for few Minutes. This Mixture is pored in Resin Bath and maintain the desired value Humidity & Temp.
Impregnation: The glass fibers are unwound from the creels and passed through a resin bath where they are thoroughly impregnated with the resin mixture.
Preforming: The impregnated fibers then pass through a preforming guide where the resin begins to pre-cure, and the fiber bundle is shaped into the rough dimensions of the final rod.
Curing (Heated Die): The impregnated, preformed fibers are pulled through a heated die, which is the heart of the pultrusion machine. The die is precisely machined to the exact dimensions of the finished rod. Inside the die, the temperature (140 Degree to 165 Degree ) is controlled to initiate and complete the curing (hardening) of the resin, which binds the fibers together.
Pulling Mechanism: The continuous rod is pulled through the die using a powerful tractor pulling mechanism, ensuring continuous production and consistent quality. The pulling speed is usually 80mm/Sec to 120mm/Sec. according to Diameter of the Rod.
Cutting: The continuous rods are then cut into predetermined lengths using a chop saw or a similar cutting device.
Post Curing: The continuous curing in the heated die don’t cure the rods completely and there will be chances of undercurve. to ensure the curing and maintaining the all the desired properties post curing is required. usually air heated oven is used for post curing at 100 degree to 150 Degree for few hours according to the diameter and Length of the rod.
Properties of the FRP Rod for Composite Insulators:
| Properties | Acceptance Values | Standards |
| Dye Penetration | No dye penetration for 15 Minutes (Min.) | IEC 61109 |
| Hardness test (barcol) | 50 Min | ASTM D 2583 |
| Specific Gravity | 1.9‐2.2 | ASTM D 792 |
| Tensile Strength | 760MPa (Min.) | ASTM D 638 |
| Flexural Strength | 500mPa (Min.) | ASTM D 349 |
| Water Absorption | 0.1 max | ASTM D570 |
| Water Diffusion Test | No Puncture at 12kV & Current shall be less than 1mA | IEC 61109 |
| Glass Content | 70% Min | ASTM D 2584 |
| Boron Content | Boron Free (0%) | ASTM D 578 |
| Glass Transition Temprature TG | 145Degree | ASTM D 3418 |
Type Test for FRP Rod:
| Tests | Standard |
| Dye Penetration Test | IEC 62217-2014 |
| Water Diffusion Test | IEC 62217-2012 |
| Brittle Fracture Test | REC Spec. 76/2006 |
| Tensile Strength | ASTM D 638 – 1991 |
| Flexural Strength | ASTM D 790 – 1992 |
| Compressive Strength | ASTM D 695 – 1991 |
| Impact Strength (Izod) | ASTM D 256 – 2006 |
| Hardness | ASTM D 2583 – 1986 |
| Stress Corrosion (1mol / 1HNO3 At 80% SML) | REC Cl No.2 |
| Die Electric Strength (Axial) In 900 C Oil | ASTM D 149 – 2009 |
| Die Electric Strength (Radial) In 900 C Oil | ASTM D 149 – 2009 |
| Die Electric Constant 500v / 50 Hz. / 25 C0 | IEC – 60250 – 1969 |
| Die Electric Dissipation Factor 500v / 50 Hz. / 25 C0 | IEC – 60112 – 2003 |
| Comparative Tracking Index | IEC – 60112 – 2003 |
| Surface Resistivity | ASTM D 257 – 2007 |
| Volume Resistivity | ASTM D 257 – 2007 |
| Martens Heat Distortion | DIN – 53462 – 1987 |
These tests ensure that E-CR glass fiber rods perform reliably in their applications, particularly in electrical insulation where failure can lead to significant operational disruptions and safety hazards. Manufacturers and industry standards often dictate the specific protocols and benchmarks for these tests, aligning them with the requirements of the electrical industry and other sectors where these rods are used.
Frequently Asked Questions
What is FRP?
FRP, or Fiber Reinforced Polymer, is a composite material consisting of a polymer matrix reinforced with fibers. These fibers—typically made from materials like glass, carbon, aramid, or basalt—provide strength and stiffness to the composite, while the polymer matrix, usually an epoxy, polyester, or vinyl ester resin, binds the fibers together and distributes loads among them. FRP is valued for its high strength-to-weight ratio, corrosion resistance, and versatility in forming complex shapes, making it widely used in various industries such as aerospace, automotive, construction, and electrical infrastructure.
What is Epoxy Resin?
Epoxy resin is a type of synthetic resin that becomes hard when mixed with a hardener. It’s known for strong adhesion, high strength, and resistance to chemicals and heat. Epoxy is widely used as an adhesive, in coatings, and for making composite materials like carbon fiber parts. It’s also popular in crafts and jewelry making because it can create a clear, durable finish.
What is Di-electric Strength?
Dielectric strength is a measure of an electrical insulating material’s ability to withstand electric stress (voltage) without failure, meaning it can resist electric breakdown and does not conduct electricity at specified conditions. It’s expressed in volts per unit thickness, typically kilovolts per millimeter (kV/mm).
What is Specific Gravity ?
Specific gravity is a measure that compares the density of a substance to the density of water. It’s a dimensionless number, meaning it has no units. If a substance has a specific gravity less than 1, it will float on water; if it’s greater than 1, it will sink. Specific gravity is commonly used to test the purity of substances and to identify minerals.
Specific Gravity=Density of WaterDensity of the Substance / Density of Water
Density Vs Specific Gravity
Density is a measurement that tells you how much mass is contained in a given volume of a substance. It’s usually expressed in terms like kilograms per cubic meter (kg/m³) or grams per cubic centimeter (g/cm³).
Specific gravity is a comparison of the density of a substance to the density of water. Unlike density, specific gravity has no units because it’s a ratio. If a substance’s specific gravity is less than 1, it will float in water; if it’s more than 1, it will sink.
Key difference:
- Density tells you how heavy a substance is for a specific volume.
- Specific gravity tells you how heavy a substance is compared to water.
