Most Common Questions about Canted Coil Springs } Advanced EMC Technologies
by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

7 Things to Know About FlexForce Canted Coil Springs

FlexForce canted coil springs have special characteristics that make them useful in a variety of applications, ranging from locking components together in an orthopaedic implant to providing an energizer for mission critical aerospace applicants. In this blog post, we will introduce seven key facts about FlexForce canted coil springs that you need to know.

Are a Specific Design for Springs

Canted coil springs, also known as slant coil or cant coil springs, are springs that have the individual coils set at an angle to each other, rather than having them all parallel. This coil configuration significantly impacts the performance of these springs and makes them ideal for a wide range of uses.

What makes canted coil springs different from other types is the fact that they have a flat load curve when they are compressed. Because of this, canted coil springs generate predictable loads throughout their wide deflection range.

Can be Used as Mechanical Connectors

Canted coil springs are ideal for applications that involve latching, locking, or holding to connect two components (also known as detent mechanisms). Latching involves fastening two parts together so that they can still be disconnected when needed. Locking creates a permanent connection that can only be broken by damaging the sea. Holding, on the other hand, both retains and aligns parts and makes sliding possible via the controlled spring force. 

Canted coils are commonly used to connect two mating surfaces in a highly predictable, repeatable fashion thanks to the flat load curve. When canted coil springs are used, the insertion/removal force can be engineered to a high degree of accuracy.  And when used as a latching, locking, or holding connector, FlexForce canted coil springs provide a lightweight, high strength option that can be used for practically an infinite number of cycles.

Can Provide Exceptional EMI/RF Shielding

One of the common uses of canted coil springs is their ability to effectively provide EMI/RF shielding. Furthermore, the electrical properties of these springs can be customized to provide more optimal shielding against certain ranges of conductive and radiated interference.  

Add to this the fact that they can adapt to irregular and uneven shapes to provide consistent shielding, and it is easy to see why they are a common choice for applications that need to be protected from harmful electromagnetic and radio frequency crosstalk interference.

Can Act as a Multiple Point Electrical Conductor

Some designs depend on multiple electrical contact points, which a canted coil can provide. Using a canted coil spring for electrical connections results in a reliable connection that results in a cooler operation temperature. It allows engineers to manage more power in compact spaces and provides both conducting and grounding capabilities in both static and dynamic applications. In addition, canted coil springs as electrical conductors can perform in some of the harshest operating environments that may involve vibration and shock. It should come as no surprise that canted coil conductors are often used in medical applications inside the human body.

Can be Used with Spring Energized Seals

Canted coil springs work extremely well as the energizer in spring-energized seals. Because of the energizer, spring energized seals are able to maintain contact with the sealing surface, even if issues such as out of roundness, uneven mating surface, runout, hardware gaps, eccentricity, or seal lip wear are present. 

The flat load curve of these springs also means that friction stays fairly consistent in dynamic sealing applications. This makes them ideal for sealing situations that involve critical friction and torque specifications. In addition, canted coil springs are very unlikely to experience compression set. 

Available With a Range of Options

There are several options for canted coil springs. They are available in varying levels of spring force: light, medium, and heavy. And canted coil springs come in both standard and custom sizes. As to the spring wire itself, they are available in wire diameters between 0.25 mm (0.010 inches) and 1.50 mm (0.059 inches). As to the coil width, they come in sizes ranging from 1.5 mm (0.039 inches) and 15 mm (0.591 inches). However, designs can be highly customized if needed.

Finally, the three most common wire materials are Hastelloy, stainless steel (usually 300 series), and copper alloys. For use as a conductor or EMI/RF shielding, stainless steel is recommended. For applications that involve high heat and corrosive media, Hastelloy and Elgiloy may be recommended. Also keep in mind that these canted coil springs can be obtained with nickel, silver, or gold plating.

Used in a Wide Range of Industries and Applications

Canted coil springs are being used in a diverse group of industries and applications, including oil & gas, renewable energy, aerospace, defense, fluid power, transportation, semiconductor manufacturing, and medical devices. 

  • As a mechanical connector, canted coil springs are often used to lock together frame assembly of a ventilator cart or to hold components together in wind turbines.
  • As a multiple contact point conductor, canted coil spring assemblies are often used in active implantables such as pacemakers or neurotransmitters. 
  • As EMI/RF shielding, canted coil springs can be found in electrical enclosures or used with data transmission cables.
  • As a part of a spring energized seal, canted coil springs are used in critical aerospace applications and dangerous petrochemical environments involving extreme heat and corrosive materials.

Conclusion

FlexForce canted coil springs can be used as detent mechanisms, EMI/RF shields, multipoint electrical conductors, and energizing springs in seals. They are available in a number of options and can be fully customized to meet user needs. In addition, their reliable performance has already been proven in number industries and applications. If you are interested in FlexForce canted coil springs, contact us at Advanced EMC today.

Hytrel for Sealing Applications
by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Benefits of Hytrel for Sealing Applications

Hytrel (property of the Dupont Company) is gaining in popularity as a material for seals, and there a number of reasons for this. In this blog post, we are going to talk about the general characteristics of Hytrel as well as the specific grades used for sealing applications.

What is Hytrel?

Hytrel is a TPC-ET thermoplastic polyester elastomer made by Dupont. Hytrel can be found in applications that seem to vary significantly in requirements and environmental challenges, such as off-road transportation equipment, oil and gas, hydraulic power, food handling, and medical devices. It is also used in electronics, automobiles, healthcare equipment, power tools, sporting goods, appliances, and cables.

Characteristics of Hytrel

Hytrel has a long list of excellent characteristics, including impact resistance, toughness, and resistance to chemical attack (including hydrocarbon solvents and fuels). In terms of sealing applicants, it offers:

  • Flex fatigue resistance
  • Spring-like properties
  • Creep resistance
  • Inherent flexibility
  • The ability to flex in multiple directions
  • Wide operating temperature range (cryogenic to +315°F)

In addition, Hytrel retains mechanical properties even at high temperatures and remains flexible at low temperatures. Hytrel also lends itself to a variety of manufacturing methods, including extrusion, blow molding, injection molding, and rotational molding. However, it is sensitive to water and phosphate fluids above 175°F.

Grades and Blends of Hytrel

Hytrel is available in various grades and blends, including seven specific grades that are well-adapted for seals. In addition to the grades discussed below, there are also renewable sourced options. Note that stabilizing additives can be combined with these grades to improve Hytrel’s resistance to heat aging and UV light.

Hytrel 4056

Hytrel 4056 is the most flexible grade, offering both toughness and strength over a considerably wide temperature range. It works extremely well for low-temperature applications because of its ability to retain flexibility. In addition, its low modulus allows it to be formed using extrusion and has a low melting point.

Hytrel 4068 and Hytrel 4069

Both Hytrel 4068 and 4069 provide flex-fatigue and creep resistance along with outstanding low-temperature properties. These grades can be formed using molding or extrusion and possess a higher melting point than Hytrel 4056 and a lower modulus. In addition, there is a food-grade available: Hytrel 4068FG.

Hytrel 4556

Hytrel 4556 is very similar to 4068 and 4069, with a low-to-medium modulus and can be manufactured using both extrusion and molding. This grade works extremely well for seals and gaskets.

Hytrel 5526 and Hytrel 5556

In terms of general properties, Hytrel 5526 provides a good balance. Its flow properties, however, primarily limit it to injection molding. Hytrel 5556 also offers a balance of properties with a medium modulus. It works well with extrusion but does not have the same high-flow properties available with Hytrel 5526. 

Hytrel 6356

Hytrel 6356 offers an excellent balance of properties such as toughness, flexibility strength, thermal resistance, and creep resistance. This high modulus grade is well adapted both to molding and extrusion processes.

Hytrel 4053FG NC010

When food contact grade seals are needed, Hytrel 4053FG NC010 may be an option. This is a low modulus extrusion grade whose properties include creep resistance, good low-temperature properties, and flex-fatigue resistance. 

Hytrel 5553FG NC010

This is a medium modulus molding and extrusion grade of Hytrel that provides a good balance of properties. It is intended for applications involving food contact.

Hytrel 6359FG NC010

Another good grade option of Hytrel, this material provides a good balance of properties including strength, toughness, flexibility, creep resistance, and thermal resistance. It is a medium to high modulus grade that works well with both molding and extrusion processes.

Benefits of Using Hytrel

When used in sealing applications, Hytrel offers a number of distinct benefits. For example, Hytrel can be used to replace multi-piece assemblies (including those composed of various materials) with a single component.

Because Hytrel has excellent creep and recovery properties, seals using Hytrel will be more resistant to dimensional changes and less likely to be permanently deformed. This is critical in many sealing applications, including those where there are extreme pressure and temperature changes. And because it can flex in multiple directions for far more cycles than a traditional elastomer such as rubber.

Unlike some seal materials, Hytrel grades vary according to modulus, which makes Hytrel a very versatile material choice. The differences in modulus are important: low modulus options can be used where little force should be needed to stretch the material, while high modulus grades work well for situations where significant force should be required to result in stretching. In addition, Hytrel is available in Shore D hardness ranging from 30 to 82.

As mentioned earlier, Hytrel has excellent properties when it comes to chemical compatibility and resistance to chemical attack. More specifically, it is resistant to mineral oils, greases, water-based hydraulic fluids, dilute acids, dilute bases, glycol, and hydrocarbon fuels. There are also grades of Hytrel that offer excellent resistance to the degrading effects of radiation. 

Hytrel is available in food grades that conform to both FDA and  European Food Contact regulations.  There are also grades in compliance with regulatory requirements that make them suitable for use in medical devices and other healthcare applications.

Conclusion

Hytrel combines the strength of engineering plastics with the flexibility of elastomers and the ease of processing provided by thermoplastics. Its combination of properties and flexibility in terms of manufacturing processes make it an excellent option for sealing applications