Certain fastening applications are especially sensitive to the flow of electrical current across their components, and to combat this, specifiers turn to non-conductive hardware as part of the solution. The reasons for seeking out non-conductive fasteners are many, and below we’ll briefly highlight a few objectives of these fasteners along with example applications:
- Protection of delicate electronics, such as in aerospace or advanced technology systems
- Isolation of transient voltage, such as in precision instrumentation that might pick up static electricity during use
- Separation of paths to ground, such as in lightning rod systems routing current to a dedicated ground instead of normal facility grounds
- Stopping galvanic corrosion, such as in fluid piping systems at the connection point between dissimilar metal piping materials
- Isolation of noise and interference frequencies, such as in high-frequency radio transmitters
- Isolation of other electrical current-inducing conditions, such as in systems where particular chemical reactions or magnetic fields can occur
In all cases, non-conductive fasteners are selected in order to contain or deter the flow of energy across a mating connection. While we described the flow of electrical energy in our above examples, non-conductive fasteners may also be selected to isolate heat energy as well. Either way, selecting a non-conductive fastener largely follows the same process as selecting any fastener, with the added step of checking the material’s electrical or thermal conductivity value to make sure that it will work as desired. From there, selecting a specification, size, thread profile, tensile strength, and the rest of the applicable details all become a function of the fastener’s material.
Non-conductive fasteners are generally offered in either a polymeric or ceramic material. Other non-conductive materials that we might be familiar with are mostly absent from fastener use (such as glass, porcelain, and paper), as they do not provide the strength or integrity needed to work as threaded fasteners. With polymers and ceramics as our choices then, let’s take a closer look at each category’s available options in the next sections.
Non-Conductive Fasteners: Polymeric Options
Polymeric fasteners make up the larger category of our two choices for non-conductive fasteners, having many more specific material options to choose from, as well as being more widely available commercially. Polymer fasteners offer excellent strength ratings, low weights, typically competitive costs, and very low conductivity factors. Nearly all design varieties are available in polymeric fasteners as are found in metallic fasteners, from head styles, thread specs, drive types, and fastener types. Selecting a polymeric fastener comes down to your desired feature-to-cost balance, as some of the more advanced (and costly) material choices may be engineered for design criteria that your application does not require.
A quick note on the term ‘polymers’: in everyday practice, you’ll often see reference to the below materials as simply ‘plastics’. From a material science perspective, ‘polymers’ is the parent term that refers to all-natural and synthetic materials consisting of long chains of monomer molecules. ‘Plastics’ are one form of polymer, entirely synthetic and typically made from a petroleum (oil) material. In other words, all plastics are polymers, but only some polymers are plastics. Further, plastic materials are differentiated in part by their manufacturing process, either being a ‘thermoplastic’ (low melting point, impact-resistant, chemical resistant) or a ‘thermoset’ (high melting point, flexible, cost-effective). We point this out because at the very technical end of specifying non-conductive fasteners, you may end up with the incorrect fastener if you use the wrong terms – please make sure to confirm the exact spec desired when ordering.
Available polymer fastener materials include:
- Nylon – a synthetic thermoplastic that is widely available, offering excellent insulation, low weight, and resistance to vibration, abrasions, and many chemicals.
- PEEK – a semi-crystalline thermoplastic made of Polyether Ether Ketone, with excellent strength, chemical / temperature / stress resistance, and high purity. PEEK can also be reinforced with glass or carbon fibers for additional strength (check conductivity values for these variants).
- PTFE – a synthetic fluoropolymer made of Polytetra Fluoro Ethylene and also known as Teflon, offering very high electrical insulation, chemical resistance, and purity up to food-grade standards.
- TPU – Thermoplastic Polyurethane also known as Isoplast, this fiberglass-reinforced plastic offers great corrosion, impact, and electrical resistance.
- PVDF – a fluoro-thermoplastic made of Polyvinylidene Fluoride and also known as Kynar, offering functional strength and chemical resistance for general applications.
- PAI – available as either a thermoset or thermoplastic made of Polyamide-imide and also known as Torlon, providing outstanding strength at high temperatures, wear resistance and overall resilience.
- PI – a high-performance engineering polymer made of Polyimide and also known as Vespel, known for i’s ultimate temperature resistance, excellent mechanical strength, and low coefficient of thermal expansion.
Do you have a non-conductive fastening application but are unsure of which specialty fastener might be best to use? E&T Fasteners offers expert support and product selection between the above options and more! Contact us to discuss your application, see our Plastic Fastener catalog here, or to see our entire fastener catalog, visit our product selection here.
Non-Conductive Fasteners: Ceramic Options
Compared to the above polymeric material options, ceramic fastener choices are significantly fewer due to the complexity and fragility inherently associated with ceramics of any types. Generally, ceramics are brittle and weak against mechanical forces typically found in fastening applications. That said, there are a few available engineered ceramic materials that excel in non-conductive uses, though in more limited styles, sizes, and availability.
The primary differentiating characteristics of ceramic materials over polymeric materials are: much higher temperature resistance (up to 2,000°C), corrosion resistance (impervious to chemical attack, oxidation, and UV degradation), and higher mechanical stiffness, rigidity, and resistance to expansion.
Available ceramic fastener materials include:
- Alumina – a synthetic ceramic made of Aluminum Oxide, featuring extremely high temperature resistance, corrosion resistance, and electrical / thermal insulation.
- Zirconia – a synthetic ceramic made by fusing zircon sand into Zirconium Oxide, offering even higher temperature resistance than Alumina, as well as great corrosion resistance and electrical / thermal insulation.
E&T Fasteners is here to help you navigate fastener and accessory options. Price quotes, availability, lead times, delivery confirmations, unique application suggestions – whatever your need, we’re here to take your call or email. For support and advice from our fully trained staff, speak with an E&T sales representative today.
About E&T Fasteners
With sales and support teams spanning the Continental US, E&T Fasteners is here to serve your hardware, fastening, and component needs both domestically and internationally. We are a stocking distributor of metallic, plastic, and exotic alloy fasteners, backed by our technical staff directly experienced in your unique applications. We can assist your specifying and selection efforts, providing engineered solutions, record-fast lead times, and stellar customer service from quote through delivery. Please let us know how we can help!