Fixture enables hardness tests in narrow tapers

A special fixture enables hardness tests to be carried out deep inside narrow internal tapers on spindles for a machine tool builder.

A special fixture designed by Indentec enables hardness tests to be carried out deep inside narrow internal tapers.

Developed for Cincinnati Milacron UK, manufacturers of vertical CNC machining centres and CNC lathes, the fixture saves having to section expensive spindles to reach specified test points in the tapers.

Previously, one in each batch of spindles had to be scrapped because of sectioning.

The fixture is employed on an Indentec 8150 SK Rockwell hardness tester with a touchscreen for display, operation and monitoring functions.

It is engineered to exploit the inherent ability of the machine's nose mounted indenter to reach into confined interiors.

After heat treatment, the semi finished spindle is clamped in a vee block, which is mounted on a carrier angled to present the tapered internal surface at right angles to the indenter.

The carrier is guided forward against a scale to identify test positions until the required test point on the taper is located beneath the indenter.

The indenter can be positioned up to an internal shoulder 50mm inside the taper, which has an opening of 20mm diameter.

A series of Rockwell tests is carried out, the carrier being indexed from test point to point against the scale.

After testing, the indentations on the taper are removed in the finishing process.

Cincinnati says that the fixture enables 100 percent testing of spindles without any scrap through sectioning.

As part of the package, Indentec has also supplied a vee block fixture for locating the spindles during Rockwell tests on internal parallel bores at the opposite ends.

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