Gear Drive Quality 12 Wars
Who provides gears with the highest quality number?
Is it Falk®, Flender®,
Hansen®, Sumitomo®?
 The
correct answer is another question ..... Why is a quality
number important? Higher quality numbers by themselves do not
assure better gear drive operation. What is important is the
performance of the gear drive under real life operating conditions.
So rather than getting into a quality number bidding war, it is better
to address the overall concept of tooth accuracy. Probably the
best way to clarify Falk's position on the quality number issue is
with the statement we developed for the Falk A+Plus® product
line: "Falk A+Plus gear drives feature case carburized and finish
ground helical gear sets".
This, along with other features, provides gear mesh performance
that is equivalent to gearing which has a quality number Q12. The
quality number system is defined by AGMA 2000 A88 (American
Gear Manufacturers Association). This is the standard for
classifying unassembled gears. The word, unassembled, here is
important because the quality number system should not be
applied to a complete gear drive. In addition to gear tooth
accuracy, there are other factors which contribute to achieving
"high gear mesh accuracy". These factors are: Housing bore
accuracy, assembly quality, and gear drive designs which take into
consideration the dynamic operating conditions. The gear mesh
performance is determined by the loaded tooth contact patterns.
These contact patterns will affect the load distribution and dynamic
factors that are used in the gear rating formulation.
The A+Plus drive level of operational accuracy is obtained by a
combination of lead and profile modifications. Again, these
modifications are not addressed in the evaluation of gear tooth
quality in AGMA 2000 A88.
As you can see, just crowing about a high gear tooth quality
number is not sufficient to assure a "quality" gear drive. We have
purchased and evaluated Flender H series, Hansen P4, and
Sumitomo P7 gear drives. The teeth of the gearing in these drives
were subjected to analytical inspection in the Falk Gear
Laboratory. The results indicated that the teeth from all three
suppliers were a minimum quality number 10 with a typical range
of quality number 10 to quality number 12. After analytical
inspection, the gear drives were load tested in the our Test
Laboratory. The results of the load tests indicated that none of the
competitors performed better than the Falk A+Plus gear drive.
We manufacture gearing by process control techniques where
the accuracy of the tooth surface is regulated by proper
management of all facets of the tooth generation. This includes:
Cutting tool accuracy, machine tool condition, machine setup, and
other factors. Under this system only a limited number of gears are
inspected for tooth accuracy. If certification of the analytical
inspections of a particular set of standard gear elements is
required, additional charges and an extension of delivery lead
times is required.
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