Hardness Test for Expanding Mandrel of Tooling & Fixture, Hardness Tester Selection Scheme

Hardness Test for Expanding Mandrel of Tooling & Fixture, Hardness Tester Selection Scheme

Received an inquiry from a customer today regarding hardness testing for our product: hardness inspection of multi-cone expanding mandrels (workholding fixture shafts). (Pictures of the test specimen are attached below.)

The workpiece consists of a quenched and tempered base material and surface-hardened working surfaces. Hardness equipment selection is required. These expanding mandrels are mostly made of 40Cr and 42CrMo. Based on workpiece characteristics, our technical team offers the following hardness testing methods:

1.Rockwell Hardness Tester (HRC scale) Test location: Hexagonal clamping flat surface of the workpiece, for measuring the HRC hardness of surface-quenched layers; it can also test the quenched and tempered hardness of the substrate.

Advantages: Simple operation and fast testing. No specimen preparation required; testing can be performed directly after cleaning and grinding the workpiece surface. The digital touchscreen directly displays HRC values. Data can be stored and exported to generate test reports, meeting traceability requirements for factory outgoing inspection.

Note: Avoid performing hardness tests directly on cylindrical outer circles or inclined taper surfaces.

2.Brinell Hardness Tester (HB scale) Brinell hardness HB is measured on the hexagonal flat surface to verify the qualification of quenched and tempered treatment, with a reference range of HB250‑300.

Note: The Brinell hardness test method applies to hardness inspection for incoming heat-treated materials and quenched & tempered processes.

3.Vickers Hardness Tester (HV) Use a micro Vickers hardness tester for hardness measurement, equipped with a CCD automatic indentation measurement system. Take sequential indentations from the surface toward the substrate along the cross-section to measure the hardness gradient and determine the effective case hardening depth. The software automatically generates hardness-depth curves and exports complete test reports.

Note: The Vickers hardness method is suitable for measuring the effective case hardening depth of taper surfaces and working surfaces. Metallographic specimen preparation is required before testing.

4.For workpieces installed on machines or large semi-finished products that cannot be easily removed and sent to the laboratory for testing, a Leeb hardness tester can be used for rapid screening. It can convert readings to HR, HB and HV hardness values.

Note: The Leeb hardness tester adopts the dynamic test principle, and the obtained data is for reference only.