Different Materials Used in Manufacturing Electrical Contact Assemblies

The selection of contact materials for your electrical contact assemblies is an incredibly important part of the planning process. It’s always advised that you discuss the application requirements with an engineer or other professional as early in the design process as possible. Of course, depending upon your specific needs, there could be multiple options available in terms of the materials to be used. Each contact material will obviously come with its own pros and cons, whether that’s a tendency toward welding or “sticking,” or simply affordability. There’s also the concern of whether or not you’ll require UL or IEC approval. To learn a bit more about the different materials used in manufacturing electrical contact assemblies, you can continue reading below.

Silver Tungsten

Also known as AgW, silver tungsten is a popular material for use in both large air and oil circuit breakers. It’s known for having a high resistance to arc erosion. It’s also a common choice for re-closures, line disconnects, and both high current contactors and switches. Thanks to its resistance to welding, it can also serve as a good shorting contact. Composites of silver tungsten that contain more silver are used quite often in circuit breakers and in high current contactors.

Copper Tungsten

Commonly known as CuW, copper tungsten is also a very popular contact material. It’s known for being heat-resistant, ablation-resistant, easy to machine, and it’s both highly thermally conductive and electrically conductive. Copper tungsten can serve as an excellent material for switches and contacts for oil-filled devices. Thus, copper tungsten is a material commonly found used in the fossil fuel industry, as well as related industrial and commercial fields. You may also find it used in some oil, gas, or even air circuit breakers.

Silver Graphite

Sometimes shown as AgC, silver graphite is popular for many electrically conductive applications. It’s also known for having the best anti-welding properties of all contact materials. Because it has the best protection against contact welding, it’s an excellent choice for closed contacts under short circuit conditions. It’s also known for having low contact resistance and low erosion. For industrial purposes, silver graphite is excellent for circuit breakers, but it’s also effective for residential circuit breakers.

This is by no means an exhaustive list. Putting together the best electrical contact assemblies always necessities identifying the appropriate materials, so it’s always recommended that you discuss your application requirements at length before making a final decision.

Contact Rivets – A Checon Perspective

Rivets used as electrical contacts are often used in low to mid-power switching applications. Checon recognizes that certain devices are best suited for a contact rivet design and we support rivet production by supplying wire to our rivet manufacturing affiliate in India as well as maintain manual and automated rivet insertion capabilities to produce assemblies in both the U.S. & India. We also recognize that there are often opportunities to move to low cost, high-reliability alternatives such as in-press wire welding or tape welding. Checon has assisted numerous customers in their design and cost out processes to help them better understand these options and appropriate application. To learn more about how electrical contact rivets are manufactured and utilized along with a more detailed explanation of the alternative cost-out opportunities, please continue reading.

Rivet Production & Assembly

Since contact rivets are formed by cold forming and brittle material can cause cracking during this process, Checon recognizes and meets the standards that the manufacturing of a solid or bi-metal contact rivet requires with consistently ductile contact material. The cold forming process can produce several different contact shapes, the most common being round with a spherical radius. Solid silver contact rivets can be produced in a variety of materials including fine silver, AgNi, AgCdO, & AgSnO. Composite bi-metal rivets are often used to save on precious metal content and expense depending upon the material system and application needs. Copper is commonly used as the base shank material. Rivet insertion to produce contact assemblies at Checon can be accomplished manually or by an automated process. Staking is carefully monitored and repeatable to ensure proper seating of the rivet with the required twist-out torque requirements.

Alternatives to RivetsChecon’s In-Press Wire & Tape Welding operation offers a low-cost option when compared with many riveted designs. High speed, one operation, in-press welding is a core competency at

Checon’s In-Press Wire & Tape Welding operation offers a low-cost option when compared with many riveted designs. High speed, one operation, in-press welding is a core competency at Checon allowing us to develop the most consistent, high quality welded contact assemblies in the industry.  By connecting our weld head design to a large bed, high-speed vertical press via an innovative actuator design, we can dramatically increase production speeds to up to 400 assemblies per minute. Both electronic & mechanical shear testing is conducted on each contact before each welded contact moves into a Checon designed Class A progressive stamping die for coining of contact shape and stamping into a final contact assembly.

For more information on how Checon can help you maximize your contact and contact assembly performance while minimizing your costs, call Paul Thomsen directly at (508) 809-5159-office, (508) 801-2417-mobile, or, email him at thomsen@checon.com.  Checon also offers an on-line live chat via our website at www.checon.com.

Different Metals Used in Making Electrical Contacts

There are several materials and alloys that are used in creating contact materials in electrical contacts, which are both meant to help construct electrically conductive connective materials. Here are some different alloy materials used in constructing electrical contacts.

Refractory Contacts

Refractory contacts are important in helping conduct electrical current through strategic placement in devices. The necessary conductivity and resistance help determine just what materials should be chosen for your product. The following are materials used to create refractory electrical contacts:

  • Silver tungsten
  • Silver Tungsten Carbide
  • Silver Graphite
  • Silver Tungsten Graphite Carbide
  • Copper Tungsten
Buttons

In successful electrical contacts manufacturing, buttons help your finished product be as effective as possible. The following are alloys used in the composition of creating both single buttons and multi-layer buttons:

  • Silver Cadmium Oxide
  • Silver Tin Oxide
  • Silver Nickel
  • Silver Alloy
  • Copper and Copper Alloy
  • Steel and Nickel Monel
  • Braze Alloy
Rivets

Rivets are created with the distinct purpose of extending that conductivity. The materials used and how they are constructed need to target the specific construction needs of the end-result product. The following are types of rivets that are manufactured to serve electrical contacts:

  • Construction
    • Solid
    • Multi-Layer
    • Head and Shank
      • Straight Side
      • Chamfer Side
      • Step Side
      • Indent
      • Chamfer
      • Riveted Assemblies
Surface Features and Shapes

Varied shapes serve distinct purposes for the benefit of your products. The following alloy distinctions can help make a more intuitive design that enables a more efficiency and resiliency. Here are some characteristics that can be expected:

  • Knurl and Score Lines
    • For Backing Designations
    • Projections
      • For Welding
      • Nibs
        • For Locating on the Substrate
        • Serrations
          • For Desired Performance
          • Shapes
              • Square
              • Rectangular
              • Circular
              • Washer
              • Cylindrical
              • Spherical

            There are a wide range of metals that are used in making electrical contacts. In order to create a manufacturing plan best suited to your product, it doesn’t hurt to consult with an electrical contacts manufacturer to learn more.

Understanding the Principles and Applications of Electrical Contact Assemblies

Electrical contact assemblies are important in creating a wide range of products and components used in electrical devices. Let’s take a look at what exactly they are, and how they work.

The Basics of Electrical Contacts

An electrical contact is a component found in an electrical circuit that helps to complete it and allow for electrical current to successfully flow from one point to another. These electrical contact components occur in switches, connectors, circuit breakers, and relays, and they can be formed out of a range of materials depending on how well those materials both successfully conduct electricity and resist corrosion over time. The materials used in electrical contacts are also often chosen related to how affordable they are and how cost effective they are over time.

Electrical Contact Assemblies

Creating these small parts and components is just one phase of the process. Some companies also offer to help assemble these parts into a specific device, taking a set design, interpreting it, and putting into action the needs of a design plan according to what electrical contacts are needed and where. These assembly services can also involve a company partnering with an assembly group in order to have them manufacture electrical contacts that meet certain custom specifications.

Types of Electrical Contacts

These conductive parts can get pretty specialized. Buttons, rivets, various conductive surface features, and an array of refractory contacts are used to make up electrical contacts. They can be made from silver tin oxide, copper tungsten, silver graphite, and a wide range of other alloys that can accommodate different needs.

Electrical contact assemblies are incredibly important in the design and manufacturing of a wide range of electronics. These tiny conductive parts make the most everyday tools we use possible, from a television remote to a light switch to our cell phones. The next time you flip that switch or turn that knob, think about the tiny parts that are all working together to connect that circuit and make it work for you.

Your Forecast Is More Than Hot Air!

Many of Checon’s major customers provide us with forecasts of one sort or another. Most are loosely based on their customers’ expected orders as well as on any additional estimates their customers may provide to them. As you can imagine, this continues on to our customers’ customer, that customer’s customer, and so on. So it comes as no surprise that any changes in demand from the end user of our products will often result in significant fluctuations in the forecasts throughout the supply chain.

For many suppliers this can lead to frustration. If you schedule production based on a forecast and the forecast then changes you may end up with excess inventory of one product and shortages of another. I’ve heard other manufactures express this frustration with statements like “their forecast is worthless”, or “full of hot air”, or “I don’t even bother to look at it”. That’s because they are using it for the wrong purpose. Don’t build based on forecast, plan with it!

Checon understands that we need a flexible manufacturing system that can respond to changes in demand both small and large. How large? Well that depends on our customer’s ability to ramp up its production. For those that can react, we have tailored our system to respond to large fluctuations. Working closely with our suppliers, we have integrated their response capabilities into a manufacturing system built on a foundation of short setup times, small production runs, strategic inventory points, and a fully automated Kanban pull system. How we load that system is based on our customer’s demand profile. The result is fast and flexible delivery that has been over 96% on-time for more than five years!

So what does this have to do with forecasts? Absolutely nothing! Checon’s agility allows us to manufacture based on our customer’s demand, not on their forecast. But their forecast can provide information about their current outlook. Will they take what they forecast? Probably not, but we can still glean valuable information from what they think they will take, and plan accordingly. So please, keep giving us your best guess at what you will need, and we’ll take it from there.

Checon Corporation a Platinum Sponsor of the 2016 HOLM IEEE Conference on Electrical Contacts October 9-12, 2016

NORTH ATTLEBORO, MA, SEPTEMBER 15, 2016: Checon Corporation is pleased to participate as a Platinum Sponsor of the upcoming 2016 HOLM IEEE Conference on Electrical Contacts, October 9-12th, in Clearwater, Florida, USA. This will be the twelfth year that Checon will co-sponsor this important technical forum covering the latest developments in the field of electrical contacts, contact materials and connectors. As a Platinum Level Sponsor and active participant in the HOLM Intensive Course that precedes the conference, Checon is committed to helping this event deliver on its promise of a dynamic program featuring technical research and practical application information critical to our customers.

Engineers, designers and research scientists interested in learning more can contact Steve Carter at carter@checon.com, or go directly to the Conference website at www.ieee-holm.com.

For additional information on Checon and Checon PMC, visit the web site at www.checon.com.

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Customer Success With Silver Tin Oxide

Years ago, in response to growing environmental concerns from Europe over the handling, use, and disposal of Cadmium (Cd) in a wide variety of electrical and industrial applications,  Checon began developing its plan to create a silver cadmium-oxide free contact material that would meet the needs of our rapidly expanding international interests as well as satisfy those of our evolving North American customers.  The initiative was no small undertaking as we knew we would be challenged by multiple cost and performance issues, compounded by the slow to market process of electrical testing and customer adoption programs. While the switching industry had already developed silver tin-oxide solutions, for several low power DC applications, the same opportunity seemed less achievable with mid to high power AC devices that depended so heavily on cadmium’s unique electrical capabilities.

Recognizing the inevitability of ROHS sanctions against continued use of cadmium in electrical contacts, Checon moved its development efforts beyond its own lab to a customer collaborative program focused on tightly monitored material testing in device application environments.  Our revised plan was to develop a new silver tin-oxide material system that performed in specific customer applications while carefully maintaining investment in existing product designs. In order to control costs and maintain the highest reliability and quality characteristics, we drilled down to identifying mechanical ductility as an essential ingredient in preserving the processing efficiencies of toplay construction, while meeting the demanding mechanical and electrical properties across many applications including AC contactor, motor protection, and telecommunications.

And so the process began to unfold with appreciative milestones in silver tin-oxide product development and testing. Backed by customer investment in the expansion of a rigorous electrical and mechanical testing program, our proprietary silver tin-oxide products offered under the Checon GTi Series are now fully approved across multiple customer product lines, actively on par with the performance of previously specified silver cadmium-oxide materials as well as outperforming our cadmium-free competition.

Given the varied interpretation and uncertainty regarding the status of cadmium exemptions both present & future, we welcome the opportunity to work directly with customers just beginning or revisiting a material change to match our tested solutions with your specific application requirements.

Please contact me directly at: thomsen@checon.com.