You’ve decided you need a custom cable assembly for your project, but your work is just beginning. The design elements of a quality custom cable assembly are closely related and largely dependent on each other. That means you often can’t make an educated decision about one element without first identifying another.
By understanding how to prioritize design elements, you’ll gain a better sense of direction.
It’s helpful to break out these assembly design elements into four main categories:
The function describes how a custom cable assembly needs to perform in a given application.
Your design decisions should be led by the performance needs of the application. Consider these critical factors:
1. Load/Signal Requirements
Power requirements involve defining the current (measured in amps), voltage (measured in volts), and electrical power (measured in watts). To determine how much energy a piece of equipment uses, calculate the power draw using the equation: amps x volts = watts.
Signal cables communicate basic information in binary and can be found in applications involving sensors or buttons. The first step in designing a signal cable is defining the requirements for bandwidth and signal speed. Bandwidth refers to the capacity for speed and is measured in bits, kilobits, megabits, or gigabits. Signal speed is not the same as bandwidth and measures the rate at which data can be transmitted in gigahertz.
2. Wire Gauge (AWG)
Once you’ve identified the power or signal demands for your custom cable assembly, you can determine the components you’ll need to carry that power or signal load (namely, the wire size and pole count). Wire size is measured according to the American Wire Gauge (AWG) scale. The larger the diameter of the wire, the smaller its gauge number will be.
3. Contacts and Pitch
Contacts are pins inside a connector made of electrically conductive material. When one contact surface touches another, it can pass on an electrical current. Contacts come in a variety of sizes and configurations. Like AWG, the current involved in a cable assembly will determine the number of contact pins needed to carry that current. The higher the current, the higher the pin count. In designs involving multiple pins, engineers will also need to determine the proper pitch, or the distance between each pin. Pitch is vital to the compatibility of two mating connectors.
The conductor is responsible for enabling the flow of an electrical current from one cable to another. The two most common conductors used in industrial cable assemblies are bare and tinned copper wires.
Bare wires cost less and may decrease production time in applications where the wiring is custom extruded. Bare wire is best-suited for crimped connectors. However, keep in mind that without a tinned coating, bare wire is more susceptible to oxidation and corrosion. Without the proper customizations in place, corrosion will reduce conductivity over time. For this reason, it’s also important to consider the operating environment.
Tinned wires are often the preferred choice for a custom cable assembly that must operate in humid or damp conditions, particularly near saltwater. The tinned coating also improves the strength of the wire, extending its lifespan. These conductors are best suited for connectors that are soldered to terminals because the tinned coating makes the soldering process easier. However, the tinned wire will add to the cost of the solution and may impact production time.
Terminals connect the wire to an electrical assembly. They can either be crimped or soldered to allow the wire to interface with a pin, post, connector, or another terminal. Given their role in an assembly, it’s crucial to identify the current rating for the connection before choosing a terminal and connector. If the terminal or connector is not properly rated for the current, it can cause overheating and damage to the terminal, not to mention serious safety concerns.
Safety and performance requirements give a product’s industry and application. Consider these safety-related factors as you think about what your custom cable assembly needs to include:
6. Regulatory Demands
Numerous national and international organizations create and implement standards for electrical manufacturing. The regulations these organizations establish will determine specific features your custom cable assembly must have to be safely used in specific applications. Some of the most important regulatory organizations you need to know include:
- International Electrotechnical Commission (IEC): an organization that prepares and publishes international standards.
- National Electrical Manufacturers Association (NEMA): a trade association that recommends and publishes policies for specific applications and industries.
- National Fire Protection Association (NFPA): a global non-profit dedicated to eliminating death, injury, and property damage due to electrical and related hazards.
- Institute of Electrical and Electronics Engineers (IEEE): the world’s largest technical professional organization dedicated to advancing technology through publications, conferences, technology standards, and professional and educational activities.
- Underwriter Laboratories (UL): a safety certification company that certifies products based on the criteria of various safety standards and regulations.
- The National Institute for Occupational Safety & Health (NIOSH): an organization that conducts research and makes recommendations for the prevention of work-related injury and illness.
- FM Approvals: a certification organization that verifies loss prevention standards backed by scientific research and testing.
7. Testing Requirements
All consumer, commercial, or industrial electronics must pass certain tests before they are deemed safe for operation. Product testing typically occurs at the completion of the manufacturing process. However, product engineers must take test requirements into consideration at every step of the design process to ensure a passing product. Certain industries and applications will have specific testing requirements. The most common tests you’ll likely need for a custom cable assembly include:
- Ingress Protection (IP) rating
- Pull Force
- Flame resistance
- Temperature cycling
Understanding how a cable assembly will perform within a specific operating environment will help you avoid factors that can degrade effectiveness, such as high temperature, water, and chemicals that can cause corrosion. For instance, your assembly may need to include underwater connectors if your application uses sensors, cameras or needs another type of electrical connectivity you will mate and unmate underwater.
Overmolding creates a protective seal around an electrical assembly to fortify the strength and integrity of the design. In many cases, overmolding is the key to passing certain product tests and certifications, such as IP rating or FM approval. Additionally, overmolding provides:
- Strain relief
- Shock resistance
- Ergonomics and angle options
- Added features, such as molded-in light indicators
Check out this guide to understand the different types of materials, designs, and technologies involved in overmolding.
The final consideration, form, refers to how a custom cable assembly aligns with certain operational capabilities. While the electrical properties of a cable assembly are paramount, the form also plays an important role in the success of your product. The two most important questions to ask yourself are:
- How will technicians interact with cables and connectors in the field?
- Are there any spatial limitations or requirements?
Connectors come in numerous shapes and sizes. Predictably, the power and signal requirements will play a factor in the size of the connector you need. Sizing must also align with spatial requirements. Some applications deal with extremely limited space, requiring low-profile solutions or microtechnologies. The size will also impact the weight of the cable assembly. In some applications, weight can bear a significant influence over performance -- for example, in transportation and aerospace, more weight means more fuel.
10. Mating Style & Cycle
Connectors are like tires on a car. The more miles you drive, the more wear and tear you’ll have on the rubber. Likewise, the more you mate and unmate a connector, the more wear and tear you’ll create on the joints and contacts. Understanding the mating demands of your cable assembly will play a critical role in its lifespan and reliability.
The mating style refers to the mechanism used to mechanically connect one connector end to another. There are four basic mating styles:
These connectors achieve mating force through torque applied when screwing one connector end into another. This mating style is preferred in rugged applications and industrial environments because the threaded nature of the connection prevents accidental decoupling.
Bayonet connectors achieve mating force through torque as well. However, this mating design is built for speed, requiring only a small twist to achieve the connection. These connectors are best for applications that involve a high mating cycle.
These connectors achieve mating force through direct pressure. They simply click into place and are most commonly used in applications with a low probability of accidental decoupling, such as assemblies housed inside an enclosure.
Snap-lock connectors are the fastest and easiest mating style, offering both a visual and audible confirmation when a proper connection is made. Mating force is achieved by direct force, just like in a friction-fit connector. However, the friction is not what secures the connection but rather a special ramping and interlocking design within the coupler housing.
These connectors are ideal for applications that involve frequent mating and unmating, particularly in environments where technicians need to move quickly.
When to Choose a Custom Cable Assembly
If a product, industry, or application places unique demands on your cable assembly, customization is likely going to be your most time- and cost-effective option.
Standard wire connectors and cable assemblies can stand their ground when it comes to features, durability, and quality. The problem is finding an off-the-shelf connector that hits every mark in terms of function, safety, protection from the elements, and form.
With custom cable assemblies, you can achieve virtually limitless performance goals.
Customizing features, especially in anticipation of specific tests and regulatory demands, also results in a higher safety and usability profile. Additionally, a custom cable assembly isn’t necessarily more expensive than standard products. By choosing every element, your design team can more easily invest in the features you need and eliminate those you do not, ensuring the value of the solution is proportionate to the physical and performance qualities.
iCONN Systems, Inc. designs and manufactures off-the-shelf, and custom interconnect solutions for even the most rigorous industries and applications. This is particularly important when it comes to industrial applications, public safety equipment, medical applications that need to meet highly specific size and functionality requirements, and other industries. Our in-house engineering team has many years of experience working with design teams to meet a wide range of requirements while accounting for costs, manufacturability, and other concerns.
Learn more about our custom cable assembly solutions.