Strasbaugh Mechanical Maintenance Procedures
Version 1.2 - April 18, 1996 7 - 17
SPINDLE PRETRAVEL ADJUSTMENT
The grind spindle feed mechanism has been explained
previously. The rear contact point of the lever arm suspending
the spindle rests on a small bar which rests on a hardened flat
pressed onto the end of the threaded sleeve. The bar is
allowed to pivot around a roll pin as the lever arm is moved on
and off the feed platform. A micrometer head is mounted on the
rear end of the bar. The micrometer rod depresses the plunger
of a precision switch to detect the condition of the lever arm
raising off the feed platform. This condition takes place during
machine initialization and during "FORCE GRINDING".
As mentioned previously, part of the machine initialization
sequence involves locating the position of each grinding wheel.
This is done by lowering the grind spindle feed mechanism until
the grind wheel comes to rest on the test wafer. This condition
is detected by the calibration switch as explained above.
During grinding if the machine is unable to grind at the
programmed feed rate the spindle will eventually be supported
by the wafer as the feed mechanism moves down. When this
occurs the lever will lift off the feed platform and trip the switch.
This condition is defined as "FORCE GRINDING". Under these
conditions the "FORCE GRINDING" message will be displayed
and the downfeed will stop until the condition goes away.
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