# Spring washers

Split, wave and conical spring washers: axial deflection, named force examples, and the limits of locking claims.

Reviewed: 2026-10-31

Tags: components, fasteners, washers, springs

SPIROL's **8.0 × 3.2 × 0.20 mm** disc spring lists **0.40 mm** free height and **0.20 mm** cone height. Its calculated design force at **0.10 mm** deflection is **20 N**. Use the specified deflection point and product curve when estimating force. Split lock washers, wave springs and serrated conical washers have separate test and application boundaries. [SPIROL design guide, printed p. 10](https://www.spirol.com/assets/files/dsc-disc-spring-design-guide-us.pdf).

## Families and functions

Specify the spring geometry and whether it is used for axial force, available travel or resistance to rotation. [NASA RP-1228, printed p. 9](https://ntrs.nasa.gov/api/citations/19900009424/downloads/19900009424.pdf), [Smalley, single-turn design](https://www.smalley.com/spring-design/single-turn).

| Family | Geometry and documented function | Distinction |
| --- | --- | --- |
| Helical split washer | A single-coil helix with separated ends; NASA describes the typical section as slightly trapezoidal. | Spring action during tightening is separate from the locking assessment after tightening. [NASA, pp. 9–10, fig. 14](https://ntrs.nasa.gov/api/citations/19900009424/downloads/19900009424.pdf) |
| Wave washer or wave spring | Axial waves in an annular spring; Smalley's single-turn products include gap and overlap forms. | Number of waves and turns, work height and load characterize a particular spring. [Smalley, single-turn design](https://www.smalley.com/spring-design/single-turn) |
| Conical disc or Belleville form | A conical washer-type spring loaded axially. | The names overlap, but SPIROL distinguishes controlled force/travel disc springs from Belleville washers primarily used for static bolt fastening. This is the supplier's product distinction, not a universal naming rule. [SPIROL, disc springs versus Belleville washers](https://my.spirol.com/resources/white-papers/the-difference-between-disc-springs-and-belleville-washers/) |

## Force, height and deflection

A spring's force corresponds to a deflected configuration. Smalley's nomenclature separates free height, work height, deflection and load. These quantities describe axial behavior; they do not describe a vibration spectrum or a loosening-test result. [Smalley, single-turn design](https://www.smalley.com/spring-design/single-turn)

For the **Smalley SSR-0125 overlap single-turn wave spring**, the public entry lists a 1.250 in. operating bore, 0.960 in. shaft clearance, three waves, 0.016 in. wire thickness and 0.133 in. radial wall. The listed load is 22 lb at a work height of 0.078 in.; free height is 0.150 in. REF and spring rate is 306 lb/in. REF. Using that reference free height, the illustrative axial deflection is 0.150 − 0.078 = **0.072 in.** This is arithmetic from the catalog configuration, not a preload setting for a bolted joint. The page requires material selection; the unselected entry does not establish a material or finish. [Smalley, SSR-0125](https://www.smalley.com/wave-spring/ssr-0125)

SPIROL’s **8.0 × 3.2 × 0.20 mm** disc row (outside diameter × inside diameter × thickness) has free height *l₀* = 0.40 mm and cone height *h₀* = 0.20 mm. Calculated design force is **20 N at s = 0.10 mm**, and **26 N at s = 0.15 mm**, corresponding to test heights *lₜ* = 0.30 and 0.25 mm. Table calculations use E = 206 kMPa (206 GPa), μ = 0.3 and DIN EN 16984. Code B here is high-carbon steel, HV 425–510/HRC 43–50; R means phosphate coated and oiled. These calculated values are not measured forces for arbitrary washers. [SPIROL design guide, printed p. 10](https://www.spirol.com/assets/files/dsc-disc-spring-design-guide-us.pdf)

SPIROL compares measured and theoretical curves for a Group 2, Series B **50 × 25.4 × 2 mm** disc. Departures increase beyond *s/h₀* = 0.75; the curves do not justify linear extrapolation to flat. [SPIROL design guide, printed p. 2](https://www.spirol.com/assets/files/dsc-disc-spring-design-guide-us.pdf) SPIROL's separate deflection paper relates cyclic life to minimum and maximum deflection and the resulting stresses; it does not make an axial force table a universal fatigue-life rating. [SPIROL, deflection range](https://my.spirol.com/resources/white-papers/how-deflection-range-affects-the-performance-of-disc-springs/)

## Conflicting locking claims and test boundaries

NASA's March 1990 manual says the typical helical washer is normally flat at full tightening and assesses its locking ability in that condition as nonexistent. It also describes smooth Belleville washers as tension-maintaining springs with no significant locking capability, distinguishing serrated surfaces. [NASA RP-1228, printed p. 9](https://ntrs.nasa.gov/api/citations/19900009424/downloads/19900009424.pdf)

WCL says deflection of its regular helical spring split lock washer generates tension that meets the needs of most commercial applications. [WCL, regular helical spring washers](https://www.wclco.com/lock-washers/helical-spring-washers/regular-helical-spring-split-lock-washers/) Separately, WCL claims the increased thickness of its hi-collar form sustains overall locking effectiveness. [WCL, hi-collar helical spring washers](https://www.wclco.com/lock-washers/helical-spring-washers/hi-collar-helical-spring-split-lock-washers/) The latter claim conflicts with the broad locking assessment in the NASA discussion. The descriptions do not present a shared specimen, preload and vibration-test configuration that resolves the disagreement. Neither a “lock washer” name nor these general statements establishes performance for every split-washer joint. [WCL, regular helical spring washers](https://www.wclco.com/lock-washers/helical-spring-washers/regular-helical-spring-split-lock-washers/), [WCL, hi-collar helical spring washers](https://www.wclco.com/lock-washers/helical-spring-washers/hi-collar-helical-spring-split-lock-washers/), [NASA, printed p. 9](https://ntrs.nasa.gov/api/citations/19900009424/downloads/19900009424.pdf)

SCHNORR's safety washer is a different product: a conical, trapezoidal-section ring with serrations on both sides. Its brochure attributes locking to friction and mechanical engagement. A plot labeled as a DIN 65151 vibration test identifies an M10 × 50 class 8.8 screw to DIN 931, an M10 class 8 nut to DIN 934, and a **VS10 safety washer**, all mechanically zinc coated. The plotted retained-pretension result is evidence for that named comparison. The page does not state vibration amplitude or frequency, and it does not establish a general rating for plain disc or wave washers. [SCHNORR brochure, pp. 24–25](https://www.schnorr-group.com/fileadmin/4_Downloads/Brochures/SCHNORR_Produktbroschuere_EN_2024-02.pdf)

The same brochure's separate comparison labels “spring washer” and “split lock washer” as different curves without identifying their part numbers. Those labels alone do not establish interchangeable specimens or conditions across the two plots. [SCHNORR, p. 31](https://www.schnorr-group.com/fileadmin/4_Downloads/Brochures/SCHNORR_Produktbroschuere_EN_2024-02.pdf)

## Standards and coverage limits

DIN Media identifies **DIN EN 16983:2017-09** as the German version of EN 16983:2016, covering disc-spring quality specifications and dimensions. It records a correction to dimension Dₑ relative to the February 2017 edition. The publisher's committee listing separately identifies **DIN EN 16984:2017-09** as the calculation standard. These are public records; the full standards were not consulted. [DIN Media, DIN EN 16983](https://www.dinmedia.de/de/norm/din-en-16983/276635494), [DIN committee publications](https://www.din.de/en/getting-involved/standards-committees/nafs/national-committees/68242/wdc-grem%3Adin21%3A54765005%21search-grem-details?masking=true)

The SPIROL guide's printed footer is ©2026, 05/26; the retrieved PDF's creation metadata is August 2026. SCHNORR's brochure identifies version 2024-02. Those document identifiers differ from the original October 30, 2026 PDT retrieval date. [SPIROL, final page](https://www.spirol.com/assets/files/dsc-disc-spring-design-guide-us.pdf), [SCHNORR, final page](https://www.schnorr-group.com/fileadmin/4_Downloads/Brochures/SCHNORR_Produktbroschuere_EN_2024-02.pdf) The article was re-reviewed on October 31, 2026 PDT, including fresh retrieval of the two WCL product pages. The cited HTML product pages provide no controlled drawing revision. This reference does not establish a universal flattening, stacking, installation-torque, reuse or fatigue rule, or a customer's qualified joint configuration.

## Related reference

[Hardware and component references](../index.md)