H |
**Hardening, Quenching** |
A treating process
for metals in which the metal material is heated to an austenitizing
temperature, quickly cooled and hardened, such as induction hardening
and flame hardening. |

**Hardness** |
The numeric representation
of the degree of hardness a material has. Hardness is expressed
in terms of the measuring method used such as Brinell, Rockwell,
Vickers and Shore. |

**Harmonic Motion** |
The motion in
which displacement x can be expressed according to the following
equation. Similar to the quadrature of a uniform circular motion.
In the equation x = a cos (ωt+φθ), a is the vibration, ω is the
oscillation frequency, (ωt + φθ) is the phase angle, φθ is the
initial phase angle. |

**Hours of Life** |
The length of time at which
devices, equipment or components can perform at a reasonable
level of proficiency when used under prescribed conditions. In
the case of indexing drives, the hours-of-life calculation is
pursuant to the life calculation for anti-frictional bearings
since all contacts are anti-frictional. Statistically, indexing
drives must live up to 95% of this calculation. |

**HRC (Rockwell Hardness)** |
A unit of Rockwell harness
or a scale used to measure the hardness of metal materials (C
scale of Rockwell hardness). Rockwell hardness is tested with
an assortment of loads and cones which are added to a reference
load and placed on top of the sample. Meanwhile, a dial gauge
is used to read the depth of the dent formed by the test load
which is then removed to leave only the reference load. The difference
of the depths is the Rockwell hardness. |

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