One of the major components of any electrical or electronic system is the cable assembly, otherwise known as the cable harness. But unfortunately, this is one of the least components that is being considered.
When a system is being designed, the cable assembly should be the first thing to consider during the design stage. This can allow you to have the best design used for the application at hand.
Keep in mind that in the assembly design, there are several components that are involved, and every component has a significant role in the application of the completed cable assembly or wire harness. In case the assembly being used is either under-designed or over-designed, it could create a negative impact on the application of the completed system.
Some of the direct questions that need to be addressed are those that are related to the environment where the assembly will be applied.
For example, if you intend to use the cable assembly in a dynamic installation, which means that it will be exposed to some level of flexing, then it is important that the components that will be used in the assembly can withstand the anticipated flex.
The same principle will also be applied if the assembly will be exposed to a harsh environment, or if the assembly will be used in an environment where it will be exposed to moisture or sunlight, or if the assembly is designed to be used in a clean room environment.
What are the Different Components of a Cable Assembly?
Here, we are going to explore the various options to think about when creating a wire harness or cable assembly.
This includes the appropriate termination technique to be used for the type of signal that will be sent through the assembly, the ideal materials to use to satisfy the expectations of the assembly installation, as well as the safety certifications that are required by the assembly depending on the environment.
Circuits or Conductors
The type and number of conductors or circuits that should be incorporated in an assembly will greatly depend on the use of the assembly. There are many options that you can choose from for the conductive material to be used, the plating needed for the conductive materials as well as the stranding needed to construct the conductor.
The most used and versatile conductor material being used is copper. This is because copper is likely compatible with various coatings to help in the termination process and to resist corrosion. If you are more concerned about the breaking capability of the conductor, then there are numerous options that you can choose from including copper alloys and copper-clad steel.
Although these materials are still utilizing copper, there is an addition of either alloys or steel such as zirconium, chromium, and cadmium, which can help in improving the breaking strength and flex life.
In a few applications, stainless steel can also be utilized as a conductor. Although, stainless steel by itself might not be a good conductive material in comparison to copper and needs to be plated to enhance its conductivity.
Keep in mind that bare copper can be vulnerable to corrosion due to its exposure to the atmosphere. That is why a lot of conductors are plated with different types of coatings so that they can be utilized in more rigorous applications as well as to prevent corrosion.
One of the most used coatings is tin, which can help in preventing corrosion when bare copper is being used. Additionally, it can also help in the termination process and is one of the more affordable coatings.
In case the cable assembly is utilized in environments where there is a higher temperature, then you can apply nickel or silver coatings so that the conductor can be used in temperatures between 200°C and 260°C.
In an assembly, the conductors can be composed of just one strand of conductive material or several smaller conductors. Ultimately, stranded conductors were created to overcome the ruggedness of solid wires and there are different variations to choose from.
The type of construction will depend on the use of the assembly. The greater the size of the conductor, the lesser will be the diameter of the strands. In this way, the conductor will become more flexible.
When choosing a conductor for your cable assembly, make sure that it is designed for its particular use. For instance, if the conductor is primarily used for providing power, then be sure to consider the amount of current it needs to carry before figuring out the size of the conductor.
If a conductor will be used for transmitting the signal, then the length of the assembly and the speed of the signal must be considered to figure out the appropriate construction of the conductor.
Fundamental Sheaths or Insulations
You can either choose Thermoplastic or Thermoset compositions for your insulators. This is also applicable when choosing the construction of the conductor, the type, the thickness, and the material used for the insulator of the basic conductors, which will be determined using the cable assembly. There are different materials that are available to meet the demands of various environments and a range of applications.
Some of the vital areas to consider are the type of fluids or chemicals that the assembly will be exposed to, the harshness of the environment where the assembly will be applied, the level and type of voltage that the assembly needs to carry, and the temperature that the cable assembly is expected to be exposed to.
It is important that all these factors should be addressed.
There are available materials that can be used for assemblies that are expected to be exposed to extreme temperatures between -65°C and +200°C or even higher.
When it comes to temperatures, one of the important factors to consider is whether the assembly will be in a static or dynamic state. In other words, whether the assembly will be exposed to some movements and if so to what temperature.
For instance, when the assembly is put in a dynamic state at higher temperatures, then rigorous compounds will be required so that they can function appropriately.
In addition, the type of insulation that will be used will be determined based on the amount of voltage or current that the cable assembly is expected to carry. It is important to consider that there are certain insulations that are incapable of handling extreme currents for a long period of time.
If you need to transmit higher-speed signals, then some insulations must be foamed by utilizing either a gas injection foaming method or a chemical foaming technique. This foaming procedure will change the insulation by forming air bubbles in the insulation so that high-speed signals can get through without being obstructed.
You can use a colored one for the primary insulation and use it for identification purposes, most especially in cables that contain more than one conductor. Coloring can be accomplished by making use of a colorant that will be combined with the compound during its initial extrusion stage. You can also add other ways of identification such as indicating a number on the insulation or including a stripe, which can be in ring-band, spiral, or longitudinal.
When creating a wire harness or cable assembly, there are several factors to think about. It is important that each specification of the design must be addressed right away before manufacturing starts.
If you neglect these crucial factors, then it could negatively affect the application of your finished product. If you require a cable assembly, then it is ideal that you should let the manufacturer know about all the details to help you in determining the appropriate cable assembly that suits your needs.
SEI offers affordable RF and microwave products. From cable assemblies, antennas, conductors, and many more. For more details, you can contact us at (408) 374-1031.