Overview
ISO 3442-3:2007 defines dimensions and geometric tests for self-centring, power-operated chucks with serrated two-piece jaws. The standard specifies 90° and 60° serration profiles (including common designations such as 1/16" × 90°, 3/32" × 90°, 1.5 × 60°, 3 × 60°), jaw-nut dimensions for different nominal chuck diameters, and the geometric test methods and tolerances needed to ensure interchangeability and predictable chuck performance. Measurements are expressed in millimetres and geometric testing is carried out with reference to ISO 230-1.
Key Topics
- Serration geometry and sizes: Defined acceptable profiles for 90° and 60° serrations; hatched-profile tolerance zones allow manufacturing flexibility while ensuring fit.
- Permissible cumulative pitch deviation: Pitch deviation tables are specified as a function of measuring length and tooth count to control serration indexing accuracy.
- Jaw nuts and threads: Dimensional limits and recommended thread sizes for jaw nuts; thread tolerance per ISO 965-3.
- Geometric tests (G1–G8):
- Body-only tests (G1, G2) - radial run-out and camming without clamping force.
- Test-mandrel run-out (G3) - accuracy of mandrels clamped near the jaw.
- Equidistance of jaw top surfaces (G4).
- Tests with machined, paired top jaws (G5, G6) - validate maximum clamping accuracy for a given diameter.
- Off-the-spindle tests (G7, G8) - for checks not requiring a test spindle.
- Test hardware & conditions:
- Test mandrels hardened and accuracy per ISO 230-1.
- Test top jaws hardened to about 60–62 HRC; functional jaw dimensions within 0.005 mm.
- Clamping force for tests and machining of top jaws set at 67% (2/3) of maximum gripping force.
Applications
- Ensures interchangeability of top jaws across power chucks used in turning, grinding and other rotating workholding.
- Used by:
- Chuck manufacturers and suppliers to design and certify serrated jaws and jaw nuts.
- Machine tool builders integrating power chucks into spindles and faceplates.
- Quality inspectors and test labs performing geometric accuracy and run-out checks.
- Purchasing and maintenance teams specifying compliant chucks for production consistency.
- Benefits include reduced setup variability, reliable concentricity of workpieces, and consistent machining accuracy.
Related Standards
- ISO 230-1:1996 - Test code for machine tools (geometric accuracy).
- ISO 965-3 - Metric screw thread tolerances (constructional threads).
- ISO 3442-1 and ISO 3442-2 - Other parts covering manually operated and tongue-and-groove power chucks.
Keywords: ISO 3442-3, power-operated chucks, serrated jaws, self-centring chucks, geometric tests, interchangeability, 60° serrations, 90° serrations, jaw nuts, ISO 230-1.
Open preview (PDF)Machine tools — Dimensions and geometric tests for self-centring chucks with two-piece jaws — Part 3: Power-operated chucks with serrated jaws