A spring washer is specified by four hard numbers: the axial load it must deliver at installed height, the bore or shaft it pilots in, the work height, and the environment it survives — and getting any one wrong invalidates the other three [S2].
The category covers DIN 2093 Belleville disc springs (8–71 mm OD, 0.3–2 mm thickness, carbon-steel default) and wave springs, which follow a separate geometry rule set: 2–20 turns, half-turn wave increments, radial wall between 3× and 10× wire thickness [S1][S2]. Spring washers are frequently misapplied as anti-loosening devices; torque-angle testing on M16 10.9 bolts tightened to 280 N·m shows the split-lock type flattens at roughly 10 N·m of pre-load, contributing negligible residual friction [S3].
Load, Work Height, and the Static vs Dynamic Stress Cap
Wave springs are engineered against a percent-stress ceiling tied to service class: static applications must hold stress at installed work height below 100%, while dynamic (fatigue-loaded) applications must stay below 80% to avoid set and length loss in operation [S2]. A wave spring whose work-height-per-turn is less than twice its wire thickness enters a non-linear regime where actual delivered load exceeds calculated load — a common failure path in miniaturised stacks below 0.250 in. OD [S2].
For Belleville disc springs to DIN 2093, the equivalent first calculation is force at deflection h (F = F₀ · f(h/h₀)), but the practical shortlist is driven by three numbers: outer diameter, free height h₀, and the desired load at a specified deflection. Stacking in series multiplies deflection at constant force; stacking in parallel multiplies force at constant deflection — a property the Borrelly PVD range is explicitly designed to exploit [S1]. The relationship between stacking, load curve shape, and fatigue life is the reason engineers standardise on DIN 2093 rather than reinventing geometries.
Bore and Shaft Geometry Constraints
Wave springs pilot in either a bore or on a shaft, and the spring's installed OD or ID must clear the mating part with allowance for expansion under load: a wave spring's OD grows as it compresses, and the OD tolerance must be budgeted against the bore diameter before selection [S2]. Minimum radial wall is set at three times wire thickness, maximum at ten times — go below the floor and the spring collapses radially, go above and you waste space and add mass without proportional load gain [S2].
DIN 2093 disc springs do not have the same radial-wall rule because the disc geometry self-supports; instead, ID and OD tolerances plus the h₀/t ratio control stability. The Borrelly PVD series covers internal diameters of 3.2–36 mm and external diameters of 8–71 mm, a span that maps to bolt sizes M3 through roughly M36 with standard C-washers [S1]. For shaft retention, consider a sealing washer where the duty is fluid isolation rather than elastic preload — different part, different selection logic.
Material, Environment, and Why Split-Lock Washers Often Don't Lock
Spring-washer material is chosen against the operating environment — high temperature, corrosive media, or dynamic loading push selection away from standard carbon steel toward stainless or specialty alloys, since operating stress concentrates at the material surface [S2]. DIN 2093 disc springs are commonly stocked in carbon steel for low-cost standard ranges; corrosion-resistant variants are specified for chemical, marine, and food-service duties [S1].
Split-lock (helical) spring washers are the most-questioned variant. Instrumented torque-angle tests on axle main-reducer M16×100 10.9-grade bolts tightened to 280 + 20 N·m show the spring washer fully flattens at roughly 10 N·m of pre-load, contributing a fraction of the friction needed to prevent self-loosening under vibration [S3]. After disassembly, no embedment marks are visible on bolt or mating surfaces, confirming that the cut-corner bite mechanism does not engage at typical pre-loads [S3]. Engineers specifying anti-loosening should reach for prevailing-torque nuts, thread-locking adhesives, or sealing washer designs rather than relying on split-lock geometry.
Selection Criteria — Disc Spring vs Wave Spring vs Split-Lock
Three variants dominate the buy decision, and the right pick is duty-driven rather than brand-driven. The comparison below lines them against four realistic selection criteria a buyer can score on a datasheet.
DIN 2093 Belleville disc springs win on heavy load per unit space, with carbon-steel stacks delivering high force in short deflection and many stacking combinations to shape the elasticity curve; sizes run 8–71 mm OD, 0.3–2 mm thickness [S1]. Wave springs win on axial space — a single wave spring can replace multiple coil-spring turns, which is why they appear in compact assemblies and motion-control products where overall length is the constraint [S2]. Split-lock spring washers are the budget option for general bolt fastening but, per the test data cited above, contribute minimal residual friction at 280 N·m pre-load and are not a reliable anti-loosening solution [S3].
For the procurement shortlist: specify DIN 2093 disc springs when load density and stack-tunable curves matter, wave springs when envelope length is the limiting dimension and the duty can be modelled against the 100%/80% stress caps, and split-lock only when the bolt is otherwise locked by other means and the washer serves as a cheap spring-feel indicator rather than a functional retainer. Buyers comparing fastener-adjacent commodities — ball valve selection or pipe clamp costing — can use the same four-criteria scoring method (load, geometry, material, standard) to keep cross-category comparison honest.
Sourcing, Standards, and Shortlist Logic
Standardisation reduces risk: DIN 2093 governs disc-spring geometry and calculation methods for the Belleville family, and a buyer who specifies "DIN 2093, carbon steel, OD X, h₀ Y" can quote across multiple suppliers without re-engineering the part [S1]. Wave-spring sourcing is less standardised — most catalogues publish working-load tables per part number rather than a single universal geometry rule, so the stress cap (100% static, 80% dynamic) and the 2–20 turns / 3×–10× radial-wall checks are the buyer's internal QA gate [S2].
For a verifiable next step, request the supplier's force-at-deflection curve for the candidate spring at three points (h = 0.25 h₀, 0.50 h₀, 0.75 h₀) and confirm the material certificate against the service environment — temperature, media, and cycle count. If a spring washer is being considered for bolt anti-loosening on a critical joint, replace the spec with a prevailing-torque nut or a verified thread-locking method; the empirical data on split-lock behaviour at 280 N·m pre-load makes the substitution a defensible engineering call rather than a cost upgrade [S3].
Spec-level background on the components involved: linear guide.