Conductors

Apar Industries Ltd. has set up a technologically advanced state of the art green field project (at Khatelwad located about 20 Km away from Vapi in western India) with 1.5 MeV and 3.0 MeV Electron Beam Accelerators along with handling systems suitable for irradiation of various types of Electrical & Automotive Cables & Wires, PE Sheets, Polymeric Tubes/ Pipes, Heat Shrink products, Gems & Diamonds, Medical product sterilization, reprocessing of PTFE scrap etc. The E-Beam irradiation curing of elastomer and other polymeric cables has several advantages over conventional steam/dry curing method.

 

E-Beam Technology

Radiation has been used in various fields such as nuclear physics, chemistry, medical and isotopes ever since X-Ray was first discovered by Roentgen in 1895. The Radiation chemistry has become popular in various industrial fields after radiation cross-linking phenomena was experimented in polyethylene in 1952. Presently over 1800 (estimated) electron accelerators based processing units are in operation worldwide with 650 units in North America, 380 in Japan, 240 in China, 6 in India (with our machines added).

As the name implies, Electron Beam is the flow of high energy electrons and the energy is obtained as kinetic energy when the electrons move in a high electric field. The radiation processing by Electron Beam is a Physical reaction caused in a material by an exposure to its irradiation. The E-Beam Irradiation is a process in which the polymer is exposed to an energetic, highly charged stream of electrons. Polymers are made of hydrocarbons having C=C as strong bond and C-H as weak bond. The principal effect of high velocity electrons is to break the existing weak hydrogen  bonds & create a free radical in the polymeric insulation materials. Similarly another electron penetrates and knocks off another H and creates another free radicals. These two free radicals react with each other and form a double bond which we call as cross-links between molecules. This crosslinking  significantly improves Thermal, Mechanical and Chemical properties of the polymer i.e. insulation & sheathing materials. Electron beam irradiation (for crosslinking) makes the polymer dimensionally more stable under the influence of heat, resistant to chemicals, solvents and high temperatures, tough and more abrasion resistant. The conventional methods of cross-linking based on thermally induced chemical reaction “chemical cross-linking”, have drawbacks that it is carried out at high temperatures which does effect the life of Polymers due to degradation caused by high temperature exposure whereas the electron-beam cross-linking is carried out  at room temperature. With the electron-beam accelerators, the insulation materials can be cross-linked within a few seconds. The homogenous irradiation ensures that the homogenous cross-linking is achieved. The term Irradiation is simply the act of applying radiation (or radiant energy) to some material.

The Electron Beam Cross Linked (EBXL) wires and cables offer superior performance in demanding application and in extreme environments. Some of the improved Mechanical Properties are:

  1. Superior performance of wire and cables in demanding applications and in extreme environments
  2. Improved Mechanical Properties:
  3. Tensile strength increases
  4. Abrasion Resistance
  5. Thermal Resistance
  6. Stress Cracking Resistance
  7. Flame Propagation Resistance
  8. Deformation Resistance
  9. Cut through Resistance

Typical working of E-Beam

  1. An Electron Gun is housed in a thick vessel
  2. Number of Electrons as a Beam (Beta Rays) is accelerated in an acceleration tube. Their power can be regulated and controlled
  3. The Electrons are directed to a scanning device magnetically
  4. The Cables are passed under the beam thru set of under-beam equipments and given exposure to predetermined doses
  5. Highly accelerated electrons penetrate the insulation or sheath of cables. This results in the generation of carbon radicals which link or cross links the polymer chains of the plastic three dimensionally with each other.

 

Different types of under beam handling systems  
Wire Handling System Trolley System PE Sheet Irradiation

Applications of Electron Beam (EB) Technology

There are several applications where the Electron Beam Technology can be deployed. At Apar, the suitable handling systems have been installed to use the facility for following products. Further identification of applications are being explored.

EB cross-linking of wire & cables: The benefits & advantages of EB cross-linking of wire & cables are well established and it is the most important commercial application of radiation technology. EPR/EPDM based formulations that can be cross-linked using EB accelerator have been developed to meet the customer specifications particularly for Railways, Ship wiring, Wind Mill cables, Solar PV cables and Building wires.

Heat shrinkable products: This is another important application for production of heat shrinkable products based on shape memory effect. These include cable termination, Bus Bar sleeves, Wrap around, Cable end caps, Breakouts and other moulded components.

Rubber sheets and moulded products: The rubber gaskets, rubber sheets, moulded rubber components can be cross-linked to achieve significantly improved mechanical properties without any deformation.

Colour enhancement of precious stones: The EB technology is widely being used in several countries including in India to enhance the colour of precious gem stones like diamonds and topaz. EB irradiation service for diamond coloration as an intermediate process is offered on a commercial basis.

EB cross-linking of polyethylene ‘O’ rings: The normal grade of PE cannot withstand operating temperature beyond 70°C unless these O-Rings are cured under Electron Beam for applications requiring dimensional stability under higher operating temperature.

Medical Sterlization: EB technology is known globally for being the best method for sterilization (compared to Ethylene Oxide treatment) of various medical products like Stents, Dental implants, Lenses etc.

Degradation of Poly tetra flouro- ethylene (PTFE): It is almost impossible to treat the PTFE scrap. According to market reports, Every year more than 20000 MT of PTFE scrap is generated which needs to be recycled, else its disposal is a major cause of concern. Scrap PTFE can be degraded under Electron Beam and thereafter grinded to fine powder. Fine Powder and Micro-fine powder can be obtained to use as industrial lubricants & coatings as well as for mixing with virgin grade to produce moulded components.

Recycling of PTFE scrap by EB Irradiation

Apar has developed advanced processing technology, set up custom production equipment, and state-of-the-art R&D laboratory along with its Electron Beam irradiation facility with suitable handling equipments to process PTFE scrap (scrap generated by machining of PTFE Rods, Sheets etc) to convert to micronized powder. There is no other processing technique to reprocess such PTFE scrap.

Poly-tetra-fluoro-ethylene (PTFE) is one of the slipperiest materials known to man. PTFE micro powders are popular additives in many industrial materials (solid or liquid) whose properties or end use are improved with the addition of PTFE’s unique characteristics. With its extremely low coefficient of friction, PTFE micro powders can enhance the appearance, improve abrasion resistance, and reduce mechanical wear and surface contamination of many materials. To be useful as an additive to other materials, it must be incorporated in it micronized form homogenously. PTFE micro powders are effective within operating temperatures from as low as -100°C to +250°C.

The processed PTFE as micronized powder finds application in Inks & Coatings, Lubes and Greases, Elastomers, Personal Care products, and many more applications like manufacture of PTFE Rods, sheets and components. Some of the Applications for PTFE powders for property enhancement are:

    • Coatings: Enables non-stick coatings and Improves wear and abrasion resistance
    • Lubricants & Grease: Increases wear and abrasion resistance and useful in high temperature applications
    • Printing Inks and Premium Paints: Improves rub resistance
    • Thermoplastics: Improves wear resistance in molded parts
    • Elastomers: Improves abrasion and tear resistance

Apar offers PTFE powder in various particle sizes ranging from 10µ to 200µ as per customer requirements and application. For printing Ink, the lower particle size (ranging from 5µ to 10µ) is required, whereas Lubricants & Grease may require particle size 50µ to 75µ, and for moulded components it may require particle size of about 200µ. The smaller the particle size, price is higher due to precise processing and lower yield.

EB Irradiation of Heat Shrink Tubes & Moulded Components

Apar’s Electron Beam technology is very useful for irradiation of Polyolefin extruded tubes used for Cable jointing kits and to repair the insulation on wires or to bundle them together, to protect wires, and to create cable entry seals, offering environmental sealing protection for connections, joints and terminals, Bus Bar sleeves, Cable end caps etc. Heat shrink tubing is a mechanically expanded extruded polyolefin tube which shrinks when heated in an effort to return to its relaxed original diameter. Heat shrink tubing is rated by its expansion ratio. Heat shrink tubing (thin wall tubing to rigid, heavy-wall tubing) is manufactured by cross-linking either by chemical process or under electron beam. It is a proven fact that such tubes cross linked under electron beam have more uniform cross linking and therefore obtain higher shrink ratio, more uniform shrink properties etc.

The under beam handling system at Apar is suitable to handle almost all varieties of heat shrink tubes and moulded components. Apar does not manufacture these tubes, instead offers its electron beam system on service center basis to various manufacturers engaged in production of heat shrink tubes and components.