The Ultimate Guide to Wire Harness Manufacturing Terminals

In today’s spotlight series, we’ll look at an easily overlooked but absolutely vital component of the wire harness manufacturing process – the humble terminal. We’ll explore how terminals provide the perfect match for conquering the connection needs of the project and are just an important consideration for our wire harness design team as any other piece in the system.

What is a terminal in wire harness manufacturing?

Simply put, wire terminals terminate conductors. Coming in a wide variety of shapes and sizes, wire terminals are specific for the connection that is required for the application. Within the greater wire harness manufacturing process, wire terminals play a critical role in establishing the necessary connection. Wire terminals have to be designed within the constraints of the project, which requires extensive expertise in custom wire harness manufacturing in order to meet the time and budgetary constraints established. 

Different Types of Wire Terminals for the Task at Hand

Getting up to date with your terminal terminology is crucial for understanding how selecting the best components for the task at hand helps the entire system run cohesively, cycle after cycle. There are many different types of terminals, including an array of specialty terminals made just for a very specific task. The most common wire harness manufacturing terminals include:

  • Push-on Terminals: these terminals are made for connecting quickly and can be configured as a male or female connection. They also have a wide variety of available options to cater to the individual application. These include considerations such as heat shrink, vinyl, nylon insulated, non-insulated, high temperature, and completely customized. We’ll dive a little deeper into the unique advantages gained from each of these options later in this post.
  • Butt Connectors and Splices: providing a wire to wire connection, these terminals are used to connect or splice two, or more, wires together. This could be to lengthen, change, or repair a certain wire. Butt connectors come with available options such as nylon or vinyl insulated, non-insulated, heat shrink, and high temperature.  These can be used in the field for repair work should a wire need splicing or repairing.
  • Ring Terminals: ring terminals are crimped or soldered and are used to connect a wire to a stud or a post.  When attached to large gauge wires they are sometimes referred to as Lug Terminals. Ring terminals are commonly used for power or ground connections. Ring terminals are usually made of a copper alloy, making them easier to solder or crimp to provide a secure, protective connection. Ring terminals come in a variety of types depending on the application such as non-insulated, vinyl, nylon, heat shrink, and high temperature.  
  • Spade Terminals: these terminals are used to connect a wire with a stud or screw to make an electrical connection. The spade terminal is common in automotive applications. Spade terminals come in a wide variety of sizes and options as well. Some of these options include non-insulated, vinyl, nylon, and heat shrink. 
  • Fork Terminals: used to connect wires to components that use a clamping hold down. Because of its shape, the fork terminal is easy to install and uninstall. Fork terminals can come non-insulated, with vinyl or nylon insulation, and with heat shrink. 
  • Bullet Terminal Connectors: bullet connectors are used a lot in automotive environments because they are pretty easy to connect and disconnect. One very commonplace they are used is in the plugs connector a trailer to a vehicle.  Another useful aspect is that they can come fully insulated to prevent moisture intrusion. Bullet terminals can be vinyl or nylon insulated or heat shrunk to meet the requirements of their intended system.
  • Bare Copper Eyelets: these unique terminals are generally used in the automotive industry as a connection for battery cables to electrical equipment. These connectors have to be able to safely conduct high voltages hence they are made of pure copper, which is an excellent conductor. 
  • Terminal Blocks and Terminal Strips: these support elements help to organize the mass of wires to different electrical circuits. This is what allows multiple wires to all be connected within the same circuit. 
  • Flagged Terminals: simple terminals that provide a secure connection in tight spaces or when another terminal such as a quick connection is not ideal. These are often called Quick Connect or Quick Disconnect terminals. Flagged terminals are easy to connect and disconnect and can be either insulated or non-insulated. They are often used to connect a wire to a circuit board that has a mating spade terminal.
  • Hook Terminals: the open-ended connector is simple, but extremely durable and effective and can be used in a variety of applications. Resembling the shape of a small hook, it can easily attach to a stud or screw. 
  • Quick Disconnect Terminals: as the name implies, this terminal is produced to easily be connected and disconnected. These are often called Flagged/Flag terminals.  The terminal can either be insulated or non-insulated, depending on the environment. Our team has integrated this type of terminal in the projects of many different clients, but primarily they are used in the automotive or industrial sectors. 
  • Specialty Terminals: at Meridian, we have decades of experience in providing custom solutions to clients. With that expertise, we can design the perfect custom terminal to meet the requirements of the project. Custom adapters and connectors like “X” and “Y” connectors help solve the complex connection aspects of the project.
  • Most terminals are crimped on the wire.  The tooling required to properly crimp a terminal is critical.  At Meridian, we have the correct tooling to crimp terminals from most major suppliers, including, but not limited to Molex®, Amp®, Amphenol®, JST®, Souriau®, Deutsch® and Panduit® to name just a few.

As you can see, the possibilities for different connections and terminals doesn’t stop at type. After our engineers figure out the perfect type of terminal to provide the desired result, then they must piece together many different available options that serve to protect and preserve the connection. We’ll cover the options for wire harness manufacturing terminals in greater detail next. 

Choosing the Best Design Options for Wire Harness Terminals

You have many different choices when it comes to your terminal’s design. Depending on the environment, there are a variety of considerations to make:

  • Heat Shrink – made for high performance, heat shrinking provides a watertight seal to the terminal connection so is best used when water, salt, or steam exposure are probable environmental risks. Resistant to abrasion and the effects of aging, heat shrink also helps with pullout strength and strain relief.
  • Vinyl Insulated – when insulation is required, vinyl affords the most economical route to go. The insulation helps to protect against short circuits.
  • Nylon Insulated – nylon insulation is more durable and can withstand higher temperatures making it ideal when the environment is hot and tough, such as might be seen by our military.
  • Non Insulated – this type of terminal is typically the most economical of the design choices. It is often used when the project does not present any special characteristics or additional protections.
  • High Temperature – typically an element like nickel plated steel is used in the terminals construction to help it withstand temperatures in the realm of 900 – 1200 degrees Fahrenheit. These can be found in common consumer applications like ovens, cars, and light fixtures.
  • Overmold – this is done when either a special shape is required, a group of terminals need to be in one package or if a certain shape is desired for cosmetic reasons.

How Terminations Get Insulated

Nylon insulation and vinyl insulation are both great options for providing protection for the terminations in your custom wire harness. Vinyl insulation is the more economical of the two but still affords great protection. That’s because vinyl insulation employs a PVC sleeve that’s tapered permanently to the barrel to protect against vibration and also provides mechanical stress relief. If you need to kick it up a notch, nylon insulation is made extremely rugged to provide maximum performance protection against high vibration and stress.

Wire Gauge Sizes for Wire Terminals 

When exploring your options for different wiring terminals, it is important to remember that there is a correct size for every wire gauge and it will always have a crimping die to match. Insulated terminals come in common sizes that correspond to a color system. Most times, wires larger than 10 gauge will be required to have a terminal that’s not insulated. Your Meridian design team will skillfully employ the perfect gauges with the appropriate terminal to efficiently solve your project’s requirements.

Why a UL Rating Matters for Wire Harness Manufacturing Terminals

Underwriters Laboratories (UL) certification is something you’ll hear us discuss often because it is such a vital piece of the manufacturing puzzle. Using UL-certified components and being a UL-approved manufacturing facility means the client benefits by knowing the things going into their product, as well as the manufacturer behind the product, have met high levels of quality assurance thresholds. Quality is determined based on testing components to know their exact specifications and tolerances and then to provide this as a standard across the industry. 

When a facility doesn’t use UL-certified components in their design they are taking a gamble with something that hasn’t been tested and retested for functionality, durability, and integrity. As a UL-approved manufacturer, our manufacturing processes have been scrutinized and have been found to be of the professional caliber required to maintain this high honor. This all translates to better products for our clients. 

With clients in industrial controls, telecommunications, military, medical, and other critical sectors, each and every product off our line is designed, tested, and retested under the most stringent of conditions so that we know it will keep on performing as intended cycle-after-cycle.

Picking the Best Terminals to Get the Job Done

Our team prides itself on solving our client’s most complex wire harness problems with a small team of elite professionals each working together to bring your project’s tough specifications to life, both on-time and on-budget. When it comes to designing the perfect product, our team excels at perfecting the minutiae, while effectively managing the ‘big picture’. Contact our team now to go over your options for a custom wire harness that perfectly meets the project’s needs.