- Huyett Marketing Department
- 07/28/2022
- Updated 05/23/2024
A
retaining ring is a simple alternative to threaded fasteners or multiple-piece fastening options when the application requires a secured shoulder on a shaft or in a bore. The ring fits into a machined groove to keep the shaft, bore, or other mating component in place. Within retaining rings, there are several designs that cater to specific application needs. Here, we'll be focusing on one: the
spiral retaining ring.
Download our one-page Spiral Retaining Ring Quick Guide
here or by clicking the image to the right.
What is a Spiral Retaining Ring?
Spiral retaining rings are used mainly in low thrust load applications both internally (in housings and bores) and externally (on shafts). They are coiled from flat wire and typically wound one to two times to reflect the design needs of that particular ring. This design differs from a standard
housing retaining ring in two essential ways.
Turns
Turns are the main structural difference between housing and spiral retaining rings. A "turn" refers to a single wound circle in the ring. They provide a few essential benefits:
- Easy Installation and Removal: The turn structure allows you to wind the ring into and ou t of place by hand in many applications. You can also simply use a screwdriver to wedge under the turns and pry the ring away from the application.
- 360° Contact: Spiral retaining rings provide complete coverage around the groove (with the exception of a small gap in the single-turn design) and keep a consistent low clearance since there are no protruding lugs.
- Greater Flexibility: The ring's flexible nature allows for physical manipulation that housing retaining rings do not have.
Coiled Wire
While standard housing rings are stamped from sheet metal, spiral rings are coiled from wire. The two main benefits of this manufacturing method are:
- Economic Production: Stamping standard housing rings from sheet metal results in excessive scrap metal waste compared to the minimal waste produced by making spiral retaining rings from wound flat wire.
- Grain Structure Strength: Since the coiled wire is bent instead of cut, the grain structure follows the contour of the spiral and keeps the strength of the grains intact. With rings made from stamped metal, the grains remain vertical or perpendicular and may not perform as well under the thrust load pressure that a comparable spiral ring could withstand.
Spiral Retaining Ring Features
Installation
Multiple ring layers offer greater axial flexibility of the ring.
Removal
Notched ring allows for easy removal with a screwdriver.
Low Profile
The 360° contact provides no gaps and a uniform profile.
Assembly
Installed axially into a housing/bore or onto a shaft.
Strength
Spiral rings have a circular grain structure for high strength.
Manufacture
Spiral rings are coiled from wire with minimal wasted material.
Function
The function of any retaining ring, including a spiral ring, is to hold a component in place on a shaft or in a bore by acting as a shoulder (most rings do this by fitting into a premade groove on the application). For this to be successful, both the ring and the groove need to withstand the application's
thrust load:
Thrust load:
The amount of force applied to a retaining ring and its groove once installed.
Huyett's Retaining Ring catalog lists the thrust load capacity for every retaining ring, both as a pound or Newton limit (depending on if it is an inch or metric ring) and as a
safety factor:
Safety Factor:
A term suggesting a safe workable thrust load capacity for a given ring or groove compared to the maximum theoretical load.
We've calculated this by taking the maximum capacity and dividing it by the safety factor. For example, if the maximum load capacity is 9,000 lbs. and the safety factor is 3, that means the workable load capacity is 3,000 lbs. In our Retaining Ring catalog, you would see 3,000 listed as the thrust load.
Spiral retaining rings offer a wide variety of thrust load capacities depending on the number of turns, their material, and their "light," "medium," or "heavy" designations. The image below illustrates a comparison of Huyett's spital retaining ring loads.
Thrust Load Comparison
INCH
SINGLE-TURN LIGHT DUTY
HOUSING DIAMETER (Dh):
0.500"
PART #:
UR
THRUST LOAD:
3,040 lbs.
2-TURN MEDIUM DUTY
HOUSING DIAMETER (Dh):
0.500"
PART #:
RR
THRUST LOAD:
5,350 lbs.
2-TURN MEDIUM-HEAVY DUTY
HOUSING DIAMETER (Dh):
0.500"
PART #:
RRT
THRUST LOAD:
6,070 lbs.
2-TURN HEAVY DUTY
HOUSING DIAMETER (Dh):
0.500"
PART #:
RRN
THRUST LOAD:
6,070 lbs.
SINGLE-TURN HEAVY DUTY
HOUSING DIAMETER (Dh):
0.500"
PART #:
FHE
THRUST LOAD:
5,693 lbs.
METRIC
SINGLE-TURN LIGHT DUTY
HOUSING DIAMETER (Dh):
25mm
PART #:
VHM
THRUST LOAD:
13,870 N.
2-TURN MEDIUM DUTY
HOUSING DIAMETER (Dh):
25mm
PART #:
MKM
THRUST LOAD:
23,415 N.
2-TURN HEAVY DUTY
(DIN SERIES)
HOUSING DIAMETER (Dh):
25mm
PART #:
DH
THRUST LOAD:
25,928 N.
2-TURN
(AEROSPACE)
HOUSING DIAMETER (Dh):
25mm
PART #:
DAH
THRUST LOAD:
27,990 N.
CHARACTERISTICS
All spiral retaining rings in this chart are made from carbon spring steel and have a Safety Factor of 3.
Thrust load is the same for internal and external styles.
It is important to note that the failure of a retaining ring application is usually the result of groove deformation, which happens when the exerted thrust load exceeds the groove's
yield strength
.
Yield Strength:
The maximum amount of pressure a material can withstand before experiencing permanent plastic deformation, or distortion.
Therefore, your application design needs to factor in the strength of the ring material and the strength of the groove material. For a more in-depth discussion of this design factor, read our
Retaining Ring Guide.
Key Measurements
There are a few key measurements – notated in the Huyett Retaining Ring catalog – for both the ring and the groove that Huyett provides to help you select the right part size and appropriate groove diameter required by your application.
Ring Measurements
- Free Diameter (Df): The outside, rim-to-rim diameter
- Section (S): The width of the flattened wire
- Thickness (T): The depth of the entire ring
Groove Measurements
- Groove Diameter (Dg): The outside, wall-to-wall diameter of the groove
- Housing Diameter (Dh): The diameter of the bore or shaft that the ring will fit into or onto
- Depth (d): The depth of the groove, compatible with the thickness of the ring
- Width (W): The width of the groove, compatible with the section of the ring
When to Use a Spiral Retaining Ring
You can find spiral retaining rings in a wide range of applications, from automotive mechanisms to sprinkler valves to children's' toys. It is beneficial to learn the unique characteristics of their design and practical considerations and weigh those against the thrust load capacity needed for your application.
Shape
Since spiral retaining rings have a smooth, constant profile, they work well in applications where you need to eliminate ring interference with the component. An example of this would be an application with high rotational speed, in which lugs could slow down or catch the ring on something and shew the rotation. Spiral rings provide a smooth circumstance with no protruding elements.
Installation and Removal
Spiral rings are touted for their simple installation and removal. Traditional retaining rings may have lugs that require retaining ring tools or pliers for installation and removal. In some applications, there may not be enough clearance for the tool, or the design may require a flexible part.
Spiral retaining rings can be wound and unwound by hand to fit in and out of grooves, which saves time and money on tools and allows for movement if the groove is hard to reach. The notches on the rings also allow for screwdrivers to simply pry the end away from the groove and either coil around the screwdriver or loosen enough to continue unwinding the ring.
Internal and External Types
There is little difference between an internal and external spiral retaining ring, other than their functions. Internal rings are installed inside a housing or bore, while external rings are installed on the outside of a shaft.
The design difference is in the small notches on the end of the ring's turns, which aid in the removal process. Internal rings leave a notch facing outwards so a screwdriver can wedge underneath it. External rings have an internal-facing notch for the same reason. This design element leaves the constant profile uninterrupted, as opposed to the protruding lugs on traditional rings.
Buying Considerations
Spiral retaining rings have several design advantages over standard housing rings:
360° Constant Profile
- No lugs
- Very little difference between internal and external types
- Good for applications that require high rotational speed
Flexible Design
- Turns keep the ring flexible and easy to maneuver
- Standard options of one or two turns available
Easy Installation
- Can be wound or unwound into and out of place with no tools
- Notches provide easy removal with a flat head screwdriver
Cost
While not usually the least expensive option within retaining rings, spiral rings offer a durable, economical alternative to other multiple-piece fastener options. Compared to other retaining rings, they are similar in price to Huyett's
interlocking rings or split rings. For the price, spiral rings offer durability, variety, and ease of use.
The Huyett Selection
Huyett offers a versatile selection of spiral retaining rings to cover a broad range of common and uncommon needs:
Spiral Retaining Rings
- Single-Turn (Light): Light duty single-turn rings used in low clearance applications. Also used as a positioning point for light loads. Radius notch on one end for removal. Narrow radial wall yields moderate thrust loads. Available in internal and external designs.
- Two-Turn (Medium): Very popular series that will accommodate light and medium bearing series thrust loads. Also available in military and aerospace specifications. Available in internal and external designs.
- Two-Turn (Medium-Heavy): Originally designed to fit MAS 50-51 grooves, RRT is a common OEM specification. Two and three-turn designs are easier to install than RRN because of multiple-turn design. Available in internal and external designs.
- Two-Turn (Heavy): Heavy-duty design for use in NAS 669-670 deep grooves in applications like double row and tapered roller bearings. Available in internal and external designs.
- Aerospace Two-Turn: Standard metric series produced to metric aerospace specifications. Fits grooves designed for two-turn spiral rings in light- and medium-duty applications. Available in internal and external designs.
Spiral Ring Types
SPIRAL RINGS PROVIDE 360 CONTACT WITH NO GAP.
SINGLE-TURN, LIGHT
INTERNAL
2-TURN, MEDIUM
INTERNAL
2-TURN, MEDIUM-HEAVY
INTERNAL
2-TURN, HEAVY
INTERNAL
SINGLE-TURN, LIGHT
EXTERNAL
2-TURN, MEDIUM
EXTERNAL
2-TURN, MEDIUM-HEAVY
EXTERNAL
2-TURN, HEAVY
EXTERNAL
AEROSPACE
EXTERNAL
Materials and Finishes
Spiral retaining rings are commonly made from different types of steels, but also come in exotic materials like Inconel®. Huyett stocks spiral retaining rings in the following materials:
- 302 Stainless Steel: This is a common material for screens, blenders, and household appliances. It is ductile yet tough and exhibits moderate corrosion resistance.
- 316 Stainless Steel: This material holds up well under extreme environments like saltwater and subzero temperatures. Along with marine applications, it is a common metal in lab and medical equipment.
- Carbon Spring Steel: Also known as "general use" steel, this material is very common and has impression yield strength, making it ideal for applications in which the steel must return to its original shape.
- Inconel: Inconel is a high-strength, nickel-chrome alloy that is highly resistant to corrosion and high temperatures. Common applications include those in high-heat environments, like the aerospace industry and in engine components, along with marine applications.
Huyett also offers the following finishes for spiral retaining rings:
- Cadmium: A soft metal that offers corrosion resistance by corroding first, to protect the underlying metal.
- Passivated: A chemical process that removes foreign matter from the substrate surface creating an oxide layer that is resistant to corrosion.
- Zinc: A coating that offers some corrosion protection (48 hours), and is widely used when aesthetics of the part are a factor.
- Zinc Yellow: A yellow dichromate coating that provides excellent salt spray protection and is particularly effective for applications exposed to seawater.
- Zinc Trivalent: A coating that meets global requirements for hexavalent-free coatings, offers 240 hours of salt spray protection, and is RoHS & End of Life Vehicles (ELV) compliant.
To learn more about all the different types of retaining rings Huyett offers, check out our
Retaining Rings FAQs page. You can also read our
Retaining Ring Identification blog and our
Retaining Ring Quick Reference Guide to compare the different types.
Find High Quality Spiral Retaining Rings
Spiral retaining rings are simple, economical fasteners that offer ease of use and flexibility in comparison to standard housing rings. Shop our selection online at huyett.com. For questions or quotes, contact our Sales team at
(785) 392-3017 or
sales@huyett.com.
