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Head Suspension Assembly Lift-Off Measurement by Centrifugal Acceleration

IP.com Disclosure Number: IPCOM000117042D
Original Publication Date: 1995-Dec-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Schreck, E: AUTHOR

Abstract

A process is disclosed for accurate and fast measurement of the lift-off acceleration of Head Suspension Assemblies (HSA) by using the centrifugal acceleration of a rotating test fixture. Mounting the HSA properly on a centrifugal test fixture allows to expose the HSA to an continuously adjustable acceleration from 0 g to the maximum achievable acceleration (around 1200g). A manual test takes about 1 minute but the test can easily be automated and thus reduce the test time even more. Common technique currently is to perform a certain number of shock tests at discrete shock values that are recorded with a high speed video camera for the subsequent analysis. This process is very expensive and time consuming.

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Head Suspension Assembly Lift-Off Measurement by Centrifugal Acceleration

      A process is disclosed for accurate and fast measurement of the
lift-off acceleration of Head Suspension Assemblies (HSA) by using
the centrifugal acceleration of a rotating test fixture.  Mounting
the HSA properly on a centrifugal test fixture allows to expose the
HSA to an continuously adjustable acceleration from 0 g to the
maximum achievable acceleration (around 1200g).  A manual test takes
about 1 minute but the test can easily be automated and thus reduce
the test time even more.  Common technique currently is to perform a
certain number of shock tests at discrete shock values that are
recorded with a high speed video camera for the subsequent analysis.
This process is very expensive and time consuming.

The Figure identifies the following:
  (1) HSA under test
  (2) electrical contact
  (3) LED or small light bulb
  (4) battery
  (5) counter mass to balance the system
  (6) box that contains the HSA under test to prevent disturbance
       due to air flow
  (7) rotating fixture
  (8) motor axle

      As long as Coriolis forces can be excluded the centrifugal
acceleration is identical to a linear shock acceleration.  Mounting
the HSA on a rotating support at a radi and spinning at a frequency f
generates an acceleration g (1g=9.81m/(s*s))
   g = (2*Pi*f)  * r /9.81

On a common test stand g-values up to 1200g can be achieved easily
(5000rpm, r=4 The Figure illustrates the proposed setup.  The...