Rugged connectors for extreme environments

Paul Boughton

David Cianciolo answers the 10 most frequently asked questions related to rugged connectors.

Rugged connectors are specifically designed to withstand extreme conditions. They are available in power, signal, fibre optic and hybrid. There is, however, no one-size-fits-all type of rugged connectors. Each connecting solution has its own individual requirements to make sure that it will work in the respective application.

Selecting the right rugged connectors is therefore not always easy. Following these 10 questions will help you to find the right specifications for the connecting needs in your device to make sure that it will work under the most extreme environments.

1. What is a rugged connector?

Rugged connectors are specifically designed to withstand extreme conditions such as high and/or low temperature, high vibrations, wet or muddy conditions and dirt. Rugged connectors can be circular or rectangular. Most rugged connectors are made of brass or aluminium and are sealed to protect against dirt and water and/or gasses. Most rugged connectors use copper alloy conductors and some integrate gold to further enhance conductivity.

2. What types of rugged connectors are available?

Fibre optic, power, signal and hybrid are all available. In fact, most commercial-grade functions, including connectors for small air or water lines, can be designed for a rugged environment. You can select an off-the-shelf solution, or modify existing connectors. Most manufacturers who focus on rugged connectors will work with you to develop a custom connector for your application.

3. Where would I use a rugged connector?

There are two things to keep in mind when deciding whether to use a rugged connector. The first is the application environment. Any time a connector comes into contact with water or dirt, or it needs to be sterilised or washed down, you will want to consider a rugged connector. The second consideration is risk-management. If you have no margin for error or a zero-error application, a rugged connector should be considered. Test and measurement applications often use rugged connectors to protect the integrity of the data they collect.

4. What characteristics should I look for in a rugged connector?

When you are first looking at your connector solution, you should work with your supplier to determine the right level of sealing, number of mating cycles, and temperature rating that you need for your unique application. When you fully understand the end-use application environment, you can select properties that will protect your solution from abrasion, corrosion and chemicals.

5. What materials should I look for in a rugged connector?

Traditionally, the toughest connectors are made up of nickel-plated brass. Today, however, aluminium and stainless steel, and even some composite plastics can be specified and still fall into a rugged connector category.

6. Can rugged connectors be sterilised?

High temperature (including steam autoclave), chemical and radiation sterilisation methods all require rugged connectors that can withstand the sterilisation process. Each sterilisation method has its own connector requirements, so be prepared to discuss exactly how the end user plans to sterilise your finished device.

7. How are rugged connectors sealed?

Sealing typically falls into two categories: environmental sealing against dust, water and other minerals, and hermetic sealing against gasses. With environmental sealing, an interface seal protects the junction between the two connectors, keeping harmful particles away from the connection area. Mounting panel seals, seals for protecting the contact areas, and cable sealing round out the areas that are needed to protect the connector and the connection. Sealing materials include Viton, a fluoropolymer with low permeation and excellent chemical resistance. EPDM (ethylene propylene rubber) is commonly used for interface o-rings that are designed to be mated and unmated in low temperatures. Hermetically sealed connectors are traditionally sealed with glass, ceramic inserts, or epoxy.

8. What role do IP ratings play?

IP ratings measure the level of protection against dust, dirt and water. Look for IP68 ratings or above for true waterproof connectors. Most IP designations have specific conditions, but IP68 ratings should be defined differently by each manufacturer, so be sure to ask what the rating represents. There is a big difference between an IP68 rating of 2hours at 20metres and an IP68 rating of 24hours at 120metres. You also want to understand whether the IP rating is for the connectors in a mated and/or unmated condition.

9. Where do I get cable assemblies for my rugged connector?

Rugged connectors need to have equally rugged cable assemblies in order to work in tough environments. Medical device manufacturers often look for silicone cables with low-friction coatings. Very few OEMs attempt to make cable assemblies in-house. Most turn to a specialty cable assembly provider or to their connector manufacturer to recommend specific cables, over-moulds and assemblies that will create a rugged interconnect solution.

10. What type of lead-time do I need for my rugged connector?

Like any other product, lead times will vary, based on what you order. Popular-sized connectors are often available off the shelf and can be ordered quickly. Creating a custom connector that is unique to your application could take 12-16weeks. Modifying an existing connector design falls somewhere in between. The best connector solutions are specified early in the design process so that you have the time to select the right size and weight connector solution for your application, possibly allowing you to build a smaller, lighter device.

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David Cianciolo is Director of Engineering of Fischer Connectors USA, Greater Atlanta. Fischer Connector is headquartered in Saint-Prex, Switzerland.

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