Home » Wire Processing: Wire Insulation Goes Green
Delphi developed a halogen-free ultra thin-wall cable for the auto industry several years ago. It’s manufactured using a mPPE recyclable coating. “Traditional methods call for PVC insulation in wiring used in a vehicle body or interior, or an XLPE insulation,” says Gruber. “Both have different impacts when it comes to the environment.
“PVC contains halogens, which are effective, but can make the insulation itself difficult to dispose of at end of life, as the halogens can escape and produce byproduct compounds if the cable is incinerated,” explains Gruber. “XLPE is halogen-free, but is not highly recyclable. Using a polyphenylene ether alloy takes care of both halogen-free and recyclability issues, yet remains cost-effective and robust.”
RS Components Ltd. recently unveiled a product called EcoWire. According to James Howarth, product manager, it “achieves expanded functionality over standard PVC-based hook-up wire with insulation that is fully recyclable.”
Using a thermoplastic that is inherently lighter, tougher and more durable than PVC, EcoWire is non-halogenic and contains no heavy metal pigments. The result is UL-approved wire that helps manufacturers meet Waste Electrical and Electronic Equipment (WEEE) requirements.
“While PVC insulation is currently a mainstay of the wire and cable industry because of its mechanical and electrical properties and low cost, it presents environmental concerns,” warns Howarth. “PVC is a halogen-containing material that emits toxic gases, toxic smoke and toxic acids when burned that are hazardous to health and equipment.
“Newer materials, principally low-smoke, zero-halogen plastics emit no dangerous gases or smokes when burned,” Howarth points out. “The drawback to low-smoke, zero-halogen is that it cannot be conveniently recycled and reused. Like PVC, it will sit in a landfill for centuries.”
EcoWire uses flexible Noryl insulation to provide an environmentally friendly alternative to PVC. Noryl is a mPPE thermoplastic that is inherently lighter, tougher and more flame resistant than PVC.
Howarth says mPPE offers a reduced wall thickness, while maintaining the same electrical properties as PVC. “The diameter of equivalent wires can be 25 percent smaller with mPPE,” he claims.
Other companies are also jumping on the green bandwagon. For instance, Dow Electrical and Telecommunications recently unveiled a new family of phthalate-free plasticizers for use in wire insulation and jacketing that are made from 100 percent recyclable feedstocks. Ecolibrium bio-based plasticizers “can help cable-makers and OEMs reduce greenhouse gas emissions by up to 40 percent,” says Jonathan Penrice, global marketing direc-tor.
The push toward lighter, smaller, thinner and more efficient wiring is also affecting insulation. “As we evolve toward thinner and thinner walls, the requirements for protecting wire haven’t really changed,” notes Chris Burns, director of electrical and electronic architecture engineering at Delphi. The company has developed halogen-free, thin-wall and ultra thin-wall 0.13 square millimeter cable for use in vehicle applications that require low-current circuits.
The cables don’t contain any restricted chemicals, such as halogens, heavy metals or phthalates. The cable’s insulation is also recyclable, and it meets chlorine- and lead-free parts requirements.
According to Burns, the insulation is half as thick as conventional coatings-0.2 millimeter, or about the thickness of two regular sheets of paper. When compared to PVC thin-wall cables, the halogen-free thin-wall cables offer up to 25 percent reduction in diameter and 45 percent reduction in area.
“The ongoing trend toward smaller diameters and more complex insulation structures will force manufacturers to look beyond the traditional use of mechanical blades, however they are configured, and explore the use of technologies like laser stripping,” predicts Smith. Laser marking has also proven to be a safe, reliable and productive alternative for some types of insulations.
“For aerospace applications, almost all wire insulation is now optimized to be marked by UV laser,” says Smith. “This gives a permanent, clean and safe mark by a photochemical reaction with the titanium dioxide in the insulation.
Traditional wire marking technologies include hot-stamp and heat-shrink identification. “Hot-stamp marking is no longer used by aerospace OEMs, as it can cause damage to the thin insulation that is now the norm for aerospace wire,” Smith points out. “Heat-shrinks are still used for non-laser markable wires, but are time-consuming to fit and add weight and bulk to a harness.” A
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