Galaxy provides info on its custom cable design process, along with cable design tips.
When it comes to designing a cable for a particular application, there are many things to consider – some more obvious than others. Generally, customers know the basics, like conductor count, AWG size, and shielding. However, sometimes customers are not as well versed on the some of the finer details, such as insulation and jacket materials, stranding, strength members, fillers, and other options. Galaxy Wire & Cable is an expert solutions provider for custom wire and cable that will make sure the cable is designed correctly for the application.
One of the most important things to consider is the environment in which the cable will be used. Will the cable be exposed to chemicals? Depending on the type of chemical, some cable jackets are superior to others. Perhaps it’s going into a rugged or extreme environment and needs to have good abrasion resistance. Some jackets will fail whereas others will perform just fine. Will the cable be exposed to UV light? Will it be submersed in water, salt or fresh? What range of temperatures will the cable be subjected to? All of these criteria are crucial in the design of a cable. Selecting a cable jacket that is able to withstand a wide range of environmental conditions is critical to the performance, and potentially the viability, of the cable itself.
The overall size requirements or limitations of the cable are sometimes overlooked and must be considered.
It is important to think about how the cable is going to be terminated. Are pins going to be crimped on the conductors, or will they be soldered? If a backshell is selected already, what are the OD restrictions? As some components can have long lead times, it’s advised to consider all of these at the time of design.
There are some applications where a cable is installed in a fixed location, and will not move. However, it may be routed in a way that flexibility is important for the installation process. Other cables may be in constant motion with millions of flex cycles. If flexibility is critical, simple things like increased strand count and spiral shields will aid in the performance of the cable. Insulation and jacket materials can have different durometers as well, and the environment the cable will be exposed to is important to consider as well.
Electrical requirements are critical to understanding when it comes to designing a cable. Not only is voltage important to know, but other requirements such as impedance and capacitance, need to be evaluated to determine the right type and amount of insulation.
Lastly, some customers require their cable to hold an agency listing from organizations like UL, CSA, CE, or another accredited firm. This requires careful scrutiny to make sure that a cable designed will be able to hold a required approval. Galaxy can assist in navigating this sometimes confusing are of certifications and safety requirement to make sure the cables have the required listings.
The cable design process involves various steps that are considered individually as well as how they all work together in the final product. Even when designing a single insulated wire, there are numerous factors to take into consideration. These include, but are not limited to, minimum and maximum temperatures, maximum voltage, and DC resistance of the insulation, as well as the conductor, size limitations, tensile strength, and working environment.
Galaxy can help guide customers through the selection process and wide range of options for conductors.
Galaxy can assist with the selection of the following conductors:
Recommended Working Temperatures:
There are many different options and combinations for shielding, depending on the cable requirements.
Foil shielding often consists of Mylar® or aluminum foil wrapped individual, pairs, or multiple wires. Foil shielding provides 100% coverage. A drain wire is commonly found with foil shields for grounding purposes.
Braid shielding is made from bare or a coated copper stranding woven into a shield surrounding the inner wires of a cable. Braid coverage is less than foil shielding and ranges from 60 – 95%.
Spiral wrap shielding is made when the shielding material is wrapped around the desired wires or core of a cable. Spiral wrap shielding provides both high flexibility and excellent coverage. However, it does not reach 100% in terms of overall coverage.
Shielding combinations are often used. The most common construction is a cable with a foil and braid shield; many coaxial cables use this combination of shielding.
Many different enhancement options are available based upon the end use and functionality of a cable. These are some options that are available.
The selections for cable insulation materials and jacketing compounds are critical to the successful use of the wire or cable in its application. Temperature, fire resistance, chemical resistance, UV resistance, durability, and flexibility are important considerations. The cable insulation materials and jacket materials make all the difference in balancing performance and cost. The general characteristics of the most commonly used insulation and jacket materials are shown in the table below.
Terminology note: Insulation describes the material that covers an individual conductor. Jacket is the term used to describe the overall material used to cover conductors, shielding and any enhancement options.
| Insulation / Jacket Type | Nominal Temperature Ratings | Fire Resistance | Chemical Resistance | UV Resistance | Durability | Flexibility | Insulation (I) and/or Jacket (J) Material |
|---|---|---|---|---|---|---|---|
| CPE / Chlorinated Polyethylene | -20°C to 105°C | E | E | E | E | F | I & J |
| EPDM / Ethylene Propylene Diene Monomer | -55°C to 125°C | P | P | E | G | E | I & J |
| ETFE / Ethylene Tetrafluroroethylene | -100°C to 150°C | G | E | E | E | E | I & J |
| FEP / Fluorinated Ethylene | -80°C to 200°C | E | E | E | G | F | I & J |
| Foamed FEP | -70°C to 200°C | E | E | E | G | F | I only |
| Foamed PFA | -100°C to 260°C | E | E | G | E | G | I only |
| Foamed PE | -60°C to 80°C | P | F | E | G | G | I only |
| Foamed TPE | -50°C to 105°C | E | F | E | G | F | I only |
| Halar® | -70°C to 150°C | E | E | E | E | F | I & J |
| HDPE &LDPE (High Density Polyethylene & Low Density Polyethylene) | -50°C to 80°C | P | G | E | G | G | I & J |
| Hytrel® | -70°C to 125°C | G | G | G | G | G | I & J |
| mPPE / Modified Polyphenylene | -40°C to 105°C | G | G | E | G | F | I only |
| Neoprene | -20°C to 90°C | G | G | G | G | F | I & J |
| PE / Polyethylene | -60°C to 80°C | P | F | E | G | F | I only |
| PFA / Perfluoroalkoxy | -200°C to 260°C | E | E | G | E | G | I & J |
| PFE / Perfluoroelastomer | -60°C to 200°C | F | G | F | F | F | I & J |
| PP / Polypropylene | -40°C to 105°C | P | E | E | F | P | I only |
| PTFE / Teflon® / Polytetrafluoroethylene | -60°C to 200°C | E | E | E | G | G | I only |
| PUR / Polyurethane | -55°C to 80°C | P | E | G | E | E | I & J |
| PVC / Polyvinyl Chloride | -20°C to 105°C | G | G | E | G | G | I & J |
| Silicone | -80°C to 180°C | G | F | E | F | E | I & J |
| Tefzel® | -70°C to 150°C | E | E | G | G | G | I & J |
| TFE / Tetrafluoroethylene | -70°C to 260°C | E | E | E | F | F | I & J |
| TPE / Thermoplastic Elastomer | -50°C to 105°C | E | F | E | G | G | I & J |
| TPR / Thermoplastic Rubber | -40°C to 90°C | F | G | G | G | E | I & J |
| XLPE / Cross-Linked Polyethylene | -40°C to 105°C | G | E | G | G | G | I & J |
| XLPO / Cross-Linked Polyolefin | -40°C to 105°C | E | G | E | G | F | I & J |
Through many years of working with customers to design and supply custom cable, Galaxy has seen many misconceptions and errors and helped customers avoid them. These are the most common missteps to avoid.
Choosing the wrong AWG sized conductor can lead to inefficiencies or safety hazards. Under-sizing can cause overheating, while over-sizing increases material costs and can make the wire unnecessarily difficult to handle.
Voltage and Ampacity not calculated properly can occur if the ambient temperature or derating factors are not properly accounted for.
Picking the incorrect insulation/jacket material can lead to cable failure under environmental conditions such as temperature, humidity, water, or chemical exposure.
Insulation materials should be chosen based on the intended use of the end product or equipment. Among the many factors that must be considered are flexibility, thermal resistance, UV resistance, and abrasion protection.
Improperly chosen / insufficient shielding can result in signal interference, crosstalk, or electromagnetic interference (EMI), especially in high-frequency or sensitive electronic applications.
Not understanding regulations or laws can result in non-compliance and could mean that the cable cannot be used for its intended application. The need for agency ratings like UL, CSA, RoHS, Low Smoke Zero Halogen and Plenum ratings must be clearly understood.
Contact us for further assistance to request a quote for custom designed cable products.
Hytrel®, Nomex® and Mylar® are registered trademarks of E. I. du Pont de Nemours and Company.
Teflon® and Tefzel® are a registered trademarks of The Chemours Company FC, LLC.
Halar® is a registered trademark of Solvay