This website requires certain cookies to work and uses other cookies to help you have the best experience. By visiting this website, certain cookies have already been set, which you may delete and block. By closing this message or continuing to use our site, you agree to the use of cookies. Visit our updated privacy and cookie policy to learn more.
This Website Uses Cookies
By closing this message or continuing to use our site, you agree to our cookie policy. Learn More
This website requires certain cookies to work and uses other cookies to help you have the best experience. By visiting this website, certain cookies have already been set, which you may delete and block. By closing this message or continuing to use our site, you agree to the use of cookies. Visit our updated privacy and cookie policy to learn more.
Assembly Magazine logo
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
Assembly Magazine logo
  • Home
  • Magazine
    • Current Issue
    • Digital Edition
    • Archives
    • Specs Book
    • How-To-Guide
    • Buyers Guide
  • Exclusives
    • Plant of the Year
      • About Plant of the Year
      • Nomination Form
    • Capital Spending
    • State of the Profession
  • Industries
    • Aerospace
    • Appliance
    • Automotive
    • Medical Devices
    • DFMA Assembly
    • Green Manufacturing
    • Lean Manufacturing
    • Electronics Assembly
    • Machinery Assembly
  • Technologies
    • Adhesives
    • Assembly Presses
    • Automated Assembly
    • Dispensing
    • Motion Control
    • Screwdriving and Riveting
    • Plastics Assembly
    • Robotics
    • Test and Inspection
    • Welding
    • Wire Processing
    • Workstations
  • Columns
    • Assembly in Action
    • Automation Profiles
    • Medical Device Assembly
    • On Campus
    • Shipulski on Design
    • The Editorial
    • XYZ
    • Moser on Manufacturing
    • 21st Century Assembly
    • Mind Your Ps and Qs
  • New Products
  • More
    • Web Exclusives
    • Classifieds
    • eNewsletter
    • Blog
    • Market Research
    • Store
    • Product Spotlight
    • White Papers
    • Integrated Showcase
    • Custom Content & Marketing Solutions
    • Monthly Quiz
    • Sponsored Insight
  • Multimedia
    • Assembly Radio
    • Assembly TV
    • Image Galleries
    • Webinars
    • Interactive Spotlights
    • eBooks
  • Events
    • Calendar
    • The Assembly Show
  • Contact
    • Contact Us
    • Advertise
  • InfoCenters
    • Collaborative Robot Revolution
    • Factory of the Future
Home » Wire Processing: Processing Coax
Wire Processing Assembly

Wire Processing: Processing Coax

March 31, 2011
John Sprovieri
KEYWORDS coaxial cable / wire stripping
Reprints
Special equipment is needed to cut, strip and crimp coaxial cable.



Anyone with a television is familiar with coaxial cable. However, this multiconductor cable is used in many more applications than connecting your television to a cable box.

In vehicles, coax connects antennas to mobile phones, radios and satellite receivers. In electric vehicles, it’s used as a power cable. In military and aerospace equipment, coax is used for radio and microwave transmission, data transmission, and instrumentation and control applications. Coax can be found in cell phone towers, recording studios and medical devices. There’s even a small piece of micro coax in every Nintendo Wii.

Because of its unique design, special equipment is needed to cut, strimp and crimp coaxial cable. Coax consists of two conductors separated by a dielectric material and wrapped by an outer jacket. The center conductor and the outer conductor form concentric cylinders with a common axis. (A variant of coax, triaxial cable, consists of three concentric conductors.)

The center conductor is typically solid or seven-stranded wire. This conductor can be copper, tinned or silver-plated copper, copper-clad steel, and copper-clad aluminum.

The dielectric can be polyethylene (PE), polypropylene, fluorinated ethylene polypropylene (FEP), polytetrafluoroethylene (PTFE), or expanded PTFE. The latter, made by Gore-Tex, is specified for its softness and flexibility.

The outer conductor, or shield, can be aluminum foil, a braided mesh of copper or aluminum, or a combination of the two. In corrugated coax, the outer conductor is made from a corrugated copper tube.

The outer jacket protects the cable from the environment. It can be made of polyvinyl chloride, PE, FEP or polyvinylidene fluoride.

Coax comes in a wide range of sizes. Jacket diameters range from 0.07 to 1.7 inches. The center conductor of micro coax can be as thin as 0.012 inch in diameter.

This machine strips semirigid coaxial cable up to 4.5 millimeters in diameter. It can also process conformable coax and Succoform noninsulated coax. Photo courtesy Schleuniger Inc.

Cutting and Stripping

Depending on the application, stripping coax may require two or three steps. In the two-step process, the jacket and the shield are removed to expose the dielectric. Then, the dielectric itself is cut to expose the center conductor. In the three-step process, the jacket is removed to expose the shield; the shield is cut to expose the dielectric; and the dielectric is removed to expose the conductor. (A triaxial cable may require a four- or five-step process.)

Because of its multilayer design, stripping coax is tricky. “You want to strip down to the center conductor without nicking it,” explains Pete Doyon, vice president of product management at Schleuniger Inc. “You want a nice, clean, flush cut on the face of the dielectric. You don’t want any particles, which can change the [cable’s transmission] characteristics at higher frequencies.

“You also want to cut the shield without damaging the dielectric. That’s tough, because as you’re cutting through the braid or foil, you’re using the dielectric as an anvil. If the dielectric is soft, like Gore-Tex, there’s nothing backing up the strands you’re trying to cut.

“You want to leave as light a nick on the dielectric as possible. It’s almost impossible not to leave a tiny mark, but some applications have strict requirements about that. For example, you’re not allowed to nick the dielectric in coax for hybrid vehicles. So [the stripping machine] will cut through maybe 80 percent of the shield, and the rest has to be done by hand.”

Ordinary wire is stripped with one or two V-shaped blades that move up and down, perpendicular to the wire. Coax is stripped with two to four straight, angled or curved blades that rotate around the wire, descending as they turn. The cable is held in place using two or more centering jaws that are concentrically aligned with the blades.

Rotary blades are typically good for 50,000 to 100,000 cables. Because rotary blades have a more generic shape than V-shaped blades, assemblers will not necessarily have to change blades to process cables of different thicknesses. However, depending on the machine, they may have to change the guide bushing to match the diameter of the cable.

Both fully and semiautomatic models are available for stripping coax. A benchtop semiautomatic machine looks like a large, electric pencil sharpener. The operator feeds one end of a cut cable into the bushing at the front of the machine. When the cable reaches the correct depth, the machine clamps it in place and the stripping blades go to work.

The machine can perform full, partial or multistage strips on any layer of the cable. Strip length and incision depth are programmable.

Depending on the operator, the cable and the number of processing steps, cycle time with a semiautomatic machine can be as little as 4 to 7 seconds per piece, or 450 to 600 pieces per hour.

The fully automatic machine looks like any other in-line machine for cutting and stripping wire, except that it includes a rotary cutter through which the cable can pass. Like other in-line machines, it can be paired with equipment for prefeeding, marking and coiling.

When stripping coax, the key to success often lies with the cable itself. “The biggest problem is the quality of the cable, because the equipment [can only reference the diameter of] the outer jacket,” says Doyon. “The machine assumes that the inner layers are concentric, but that’s not always the case. If you look at cheap cable from overseas, the thickness of the outer jacket can vary quite a bit, and that will affect the stripping of the underlying layers.”

Stripping machines can perform full, partial or multistage strips on any layer of a coaxial cable. Strip length and incision depth are programmable. Photo courtesy Schleuniger Inc.

Crimping Coax

Until recently, connectors for coaxial cable were only available as loose parts. For example, a video connector consisted of a body, a ring ferrule and, perhaps, a contact for the center conductor. The number of pieces made automating the crimping process difficult, since each part had to be attached separately.

Today, thanks to the increasing use of coax in the automotive industry, one-piece, plastic-bodied connectors are now available from a number of suppliers. Called FAKRA connectors, these parts can be supplied daisy-chained on reels, just like metal terminals for conventional wire. And though a special applicator is needed, the connectors can be installed in one processing step with the same presses used for conventional wire.

FAKRA connectors require different process monitoring protocols than conventional wires. Because the machine performs two to three crimps simultaneously, pull force testing and crimp force monitoring are not the reliable indicators of quality they are with conventional wires.

“If the crimp force is way off, that can give you an indication of [a gross defect.] But otherwise, you don’t know what you’re looking at,” admits Doyon. “The force might be high in one zone and low in another, but the net could be OK.”

Instead, the best indicator of quality with FAKRA connectors is to periodically measure the height and width of each crimp.

subscribe to assembly

Recent Articles by John Sprovieri

What’s New From the ASSEMBLY Show

System feeds parts for ear protection devices

Robots assemble hydraulic valves

Right-to-repair law could affect product design

Soft Robotics Introduces Modular, Flexible Gripper for UR Cobots

Sprovieri200
John has been with ASSEMBLY magazine since February 1997. John was formerly with a national medical news magazine, and has written for Pathology Today and the Green Bay Press-Gazette. John holds a B.A. in journalism from Northwestern University, Medill School of Journalism.

Related Articles

Automated Processing of Small RF and Coax Cables

Wire Processing: Crimping Connections

Wire Processing: Passing the Test

Wire Processing: Automating Harness Assembly

Related Products

Assembly Processes: Finishing, Packaging, and Automation

The Basics of Self-Balancing Processes: True Lean Continuous Flow

The Automotive Body Manufacturing Systems and Processes

Welding Processes Handbook, 2nd Edition

Subscribe For Free!
  • Print & Digital Edition Subscriptions
  • Assembly eNewsletters
  • Online Registration
  • Subscription Customer Service
  • Mobile App

More Videos

Popular Stories

lordstown motors

Electric Truck Manufacturer Buys GM’s Lordstown Assembly Plant

Bobcat manufacturing

Bobcat Announces Manufacturing and Assembly Facility Upgrades

Wearable Device 11-27

Wearable Lets Users Control IoT-Enabled Devices With Brain Waves

Rayovac 11-20

Energizer Moving VT Battery Manufacturing Facility to Former Rayovac Plant

Breaking and Industry News

Airstream Manufacturing Expands With $50 Million Factory

Upcoming Assembly Events and Webinars

Events

January 1, 2030

Webinar Sponsorship Information

For webinar sponsorship information, visit www.bnpevents.com/webinars or email webinars@bnpmedia.com.

View All Submit An Event

Poll

Cloud Computing

Are you using cloud computing at your assembly plant?
View Results Poll Archive

Products

Welding: Principles & Practices

Welding: Principles & Practices

This text introduces students to a solid background in the basic principles and practices of welding.

See More Products
assembly buyers guide

Assembly Magazine

assembly dec 2019

2019 December

The 2019 December Assembly features our Capital Spending Report, plus much more. Check it out today!
View More Create Account
  • More
    • Assembly Plant of the Year
    • Manufacturing Group
    • List Rental
    • Organizations
    • Connect
    • Want More?
    • Polls
    • Privacy Policy
    • Subscribe
    • Survey And Sample

Copyright ©2019. All Rights Reserved BNP Media.

Design, CMS, Hosting & Web Development :: ePublishing