DE-STA-CO PN500 - Manual (Page 40)

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SECTION 9: THINGS TO AVOID
An Industrial Motion Control Indexer is a relatively simple mechanism using an input shaft
mounted, tapered, ribbed barrel cam to drive roller followers on the output hub. While simple in
concept, the precision nature of the indexer’s manufacture indicates that they must be used
within their design constraints. The indexer is, after all, just a mechanical device. In this regard
there are several situations which should be avoided to protect your warranty and maximize
indexer life.
Off-center loading, such as might be seen when a large press is used in
conjunction with an indexer, requires a back-up support anvil under the dial.
The bearings of an indexer are very heavy duty, but their life will be shortened
dramatically by unsupported, asymmetrical loading. The support anvil is typically
designed with .001” of clearance under the dial and is strong enough to carry the full
load of the asymmetrical load. Consult Industrial Motion Control Technical Sales
Department at 1-800-645-5207 or 847-459-5200 for assistance in all asymmetrical
load situations.
E-Stop Usage should be limited to emergency situations only. E-Stops should not
be used to jog an indexer. The E-Stop function causes extreme load conditions
inside the indexer by virtue of the instantaneous stopping of significant weights.
This is not unlike driving a car into a brick wall. Excessive use of the E-Stop will
significantly shorten the life of the indexer.
Starting and Stopping while in the motion profile of the cam will also put high
loading on the indexer’s internal components. Should it be necessary to stop/start
the indexer in any position other than the dwell of the cam, it is best to reduce motor
speed to avoid overloading the unit.
Shock Loading may also lead to problems. Shock loading typically occurs when
there is looseness in the input drive train or where the output load is not stable. This
condition will eventually damage either the indexer’s followers or cam. Overload
devices, that are not set correctly, are sometimes a source of this condition. Chain
drives or loose timing belt drives are also potentials.
Machine Jams, like E-Stops, put excessive loading on an indexer. While the impact
of jams is minimized by the use of overload devices, it is always best to track the
occurrence of jams and, when possible, rectify the condition that led to the jam.
A high jam frequency will shorten indexer life.