Custom External Spline Shafts
DIN 5480 / ISO 4156 / ANSI B92.1

An external spline shaft has longitudinal teeth cut along its outer cylindrical surface that mesh with matching internal splines in a hub, sleeve, or coupling to transmit torque. The involute tooth profile (DIN 5480, ISO 4156, ANSI B92.1) distributes torque across all teeth simultaneously, giving higher torque capacity, better concentricity, and smoother axial sliding than a single keyed shaft.

DIN 5480 is the European metric standard — tooth module defines tooth size, pressure angle 30°, dominant in European automotive and industrial applications. ANSI B92.1 is the American involute spline standard — uses diametral pitch (teeth per inch of pitch diameter) and comes in 30°, 37.5°, or 45° pressure angle variants. B92.1 is dominant in North American automotive and hydraulic applications. Both define fully interchangeable involute spline geometry — just with different sizing conventions. HXC produces spline shafts to both standards; specify your standard and fit class on the drawing.

For sliding fits (axial movement in service, e.g., driveshaft slip yokes, gearbox sliding hubs): DIN 5480 shaft tolerance e (e.g., 30×2×28e) mating with hub tolerance H. This gives a clearance fit with enough tolerance to slide freely without binding even after lubrication loss. For closer-fitting sliding joints with minimal backlash (servo robot joints): shaft f / hub H. For fixed couplings (no sliding): shaft js or k / hub JS or K. Always specify the shaft tolerance letter AND the hub tolerance letter together.

External spline shafts are inspected with: (1) Go/no-go plug gauge — functional check of total composite tolerance. (2) Over-pin measurement — two precision pins in opposite tooth spaces; span measured with micrometer. Directly measures effective tooth thickness. (3) CMM with gear module — for precision grades, individual tooth profile, pitch error, helix, and runout per DIN 5480 or ANSI B92.1. HXC provides 100% go/no-go gauging on all orders with CMM lot reports on precision grades (5–6).

For servo robot joints requiring low backlash and repeatable positioning: DIN 5480 grade 5 — requires post-hardening spline tooth grinding. Achieves tooth thickness tolerance ±0.005 mm and profile error ≤ 0.006 mm. For automotive transmissions and hydraulic drives: grade 6–7 (hobbed + hardened, or hobbed + hardened + light grinding). For general industrial couplings: grade 8–9 (hobbed, no grinding). Each grade step down roughly doubles inspection and production cost.

42CrMo4 induction-hardened to HRC 52–58: standard for automotive and industrial. 20CrMnTi carburized to HRC 58–62: maximum contact fatigue for high-torque drive shafts. SUS316L passivated: food, pharma, marine. Al 7075-T6 hard-anodized: lightweight robot joints. Ti Grade 5: aerospace, biocompatible. 17-4PH stainless: marine and defence. PEEK: medical and sterilizable applications.

A DIN 5480 designation has the format: DIN 5480 – W 30 × 2 × 14 × 9f where: W = external spline; 30 = reference diameter (mm); 2 = module; 14 = tooth count; 9f = tolerance class (quality grade 9, shaft position f). Always specify the designation on your drawing — do not rely on the manufacturer to infer the standard from dimensions alone.

Yes — HXC regularly supplies matched external spline shaft and internal spline sleeve sets from the same production batch. The shaft and hub are gauged together to confirm the target fit class. Matched sets eliminate tolerance stack risk when sourcing both halves separately. Sets are bagged together with one inspection report showing shaft and hub over-pin measurements and the calculated assembly clearance.

DIN 5480 specifies a minimum of 6 teeth for a valid involute spline. In practice, 10–16 teeth are typical for small-diameter shafts (Ø8–20 mm) and 20–40 teeth for larger diameters. More teeth distribute load more evenly and allow finer angular indexing, but each tooth becomes thinner, reducing bending strength. The module choice (tooth size) balances number of teeth against individual tooth strength for the shaft diameter and torque requirement.

Our between-centres grinding capacity allows spline shaft lengths up to 1,200 mm. Shafts longer than 600 mm require straightening after heat treatment before grinding — heat treatment distortion in long slender shafts is a key quality risk that our process manages with press straightening between hardening and grinding. For shafts >800 mm, we recommend discussing material and heat treatment selection with our engineers to minimise distortion.

Fixed couplings (no axial movement): a thin film of MoS₂ grease or anti-seize compound at assembly is sufficient. Sliding spline shafts (driveshaft yokes): require NLGI 2 spline grease with MoS₂ or graphite, replenished per maintenance schedule. Gearbox internals: lubricated by transmission oil — confirm API GL-4 or GL-5 compatibility. Stainless and titanium in food/medical: NSF H1 food-grade grease or run dry in light-duty applications.

Prototype (1–5 pcs, 5-axis milled): 5–8 days. Small batch (10–50 pcs, hobbed + ground, DIN 5480 grade 6): 8–14 days. Production (100–2,000 pcs, hobbed + hardened + ground): 12–18 days. Stainless or titanium: add 3–5 days. Long shafts (>500 mm): add 2–3 days for straightness correction after heat treatment.