Keyways

Identify the complete keyed connection

Specify the shaft slot, hub slot and key as one connection. A common width does not establish mating fit or torque capacity.

Original load translation: for an assumed torque of 100 N·m acting at an ideal 15 mm radius, tangential force is 100 / 0.015 = 6667 N, approximately 6.67 kN. This is equilibrium only; it does not allocate contact pressure, establish fatigue life or validate an 8 mm key. Use the actual joint model and applicable design method for acceptance.

This reference focuses on parallel-key connections. Tapered keys, Woodruff keys, splines and keyless locking devices require their own geometry and load-transfer definitions. DIN 6885-1:2021-11 is specifically titled parallel keys/keyways, deep pattern, dimensions, tolerances and mass. DIN's public record identifies it as the corrected edition replacing June 2021. It is not a general rating for every keyed joint. DIN Media, DIN 6885-1

Keep the governing standard and edition with the dimensions. An inch key and a metric key of approximately the same width are not automatically substitutes.

Geometry and reference dimensions

Depth may be stated from a cylindrical surface, or through a measurement spanning the feature and opposite surface. Preserve the actual reference rather than treating every table symbol as interchangeable. Also distinguish total slot length from useful engagement where rounded ends, chamfers or incomplete contact occur.

Ganter labels inspection dimensions d + t₂ for the hub and d − t₄ for the shaft. Its undated extract does not verify the current DIN edition. Ganter DIN 6885-1 extract

Fit is a property of both members

Ganter's extract distinguishes P9/P9 hub/shaft slots for tight fit, JS9/N9 for loose fit and D10/H9 for sliding. These are source-specific categories; width fit, radial clearance and bore fit remain separate. Ganter fit table

A named machine example reinforces the distinction: SEW-EURODRIVE's DRN gearmotor documentation, edition 02/2026, specifies hollow-shaft bore tolerance H7 and keyway width JS9. It also lists low-form DIN 6885-3 exceptions for the WA.37 shaft at 25 mm and KA.29 shaft at 30 mm. Preserve those exact product exceptions rather than assuming every shaft in a family uses the deep-pattern key. SEW-EURODRIVE hollow shafts

Select fits against assembly, service and the component maker's requirements. Do not use a tolerance-zone label without the nominal size and applicable limit table. A nominally correct slot can still be unsuitable if its position, straightness or engagement is wrong.

Bounded dimensional example

Ganter's d = 30 mm row lists an 8 mm slot width, 7 mm key height, hub radial depth 3.3 mm +0.2, and shaft radial depth 4.0 mm +0.2. Its corresponding nominal inspection dimensions are 33.3 mm and 26.0 mm. These values do not establish strength. Ganter, 30 mm row

At nominal values, combined radial slot depth minus nominal key height is 3.3 + 4.0 − 7.0 = 0.3 mm. This is a simplified dimensional check, excluding key-height, bore and shaft tolerances. It does not establish the actual installed clearance or permit bottoming the key to achieve a desired fit.

Manufacturing access and blind features

Choose the process against shaft versus internal-hub geometry, material condition, required end form and tool access. The word “keyway” does not imply a single cutting method or tool. A blind internal slot needs an explicit end condition and a process capable of producing it.

National Machine Tool's Keyseat Miller is a named example: the manufacturer describes a machine-tool attachment that mills internal keyways in blind or open-ended bores, using the bore and tool for a sliding fit. Its stated capability includes blind bores without relief. This does not establish that an ordinary push broach can do the same work or that all blind slots require the same relief. No technical revision date was verified on the pages. National Machine Tool capabilities, tool operating principle

Agree machining clearance, burr removal and inspection before finalizing a blind slot. If the process requires a runout, groove or other relief, include that actual feature in the drawing and strength review rather than adding it informally during manufacture.

Torque capacity and axial retention

A key-size table does not establish permissible torque. Review key loading and contact, engagement, key/shaft/hub material and condition, surrounding section, operating reversals and the full load history. Consider how the slot changes the shaft/hub geometry and evaluate the actual transitions where local stress matters.

KTR's REVOLEX KX/KX-D instructions, KTR-N 49410 EN edition 16, printed drawn November 4, 2022 and verified July 4, 2025, separately call for H7 bores, DIN 6885-1 JS9 keyways and axial fastening. Its finish-bore instructions limit permissible bore diameters and require concentricity/axial-runout attention. These are product-specific machining requirements, not generic keyway tolerances. KTR REVOLEX instructions

Drawing and receiving checks

1. Identify key standard/edition, form, material and the intended shaft/hub fit.
2. Define width, radial depth, reference dimensions, length and transitions for each member.
3. Review load capacity, remaining material and axial retention separately.
4. Obtain manufacturing review for access, blind ends and required reliefs.
5. Inspect dimensions, position, edge condition and actual assembly against agreed limits.

For agent-readable records, keep shaft slot, hub slot and key as separate linked features. Retain units, symbols/reference diagrams, tolerance classes and source editions, and distinguish catalogue geometry from an approved operating rating.