Tech Briefs Magazine - August 2024 - MD-12

bearing with high precision and excellent
repeatability can consistently
reach that specified position throughout
its lifespan.
However, excessive wear can comprothe
bearing's
The Impact of Bearing Failure in
Critical Applications
When a bearing fails, it can have casmise
repeatability.
This
wear increases the clearance between
the bearing components, leading to a
lower repeatability score. Therefore, it's
vital to manage the end-of-life wear on
all bearings effectively.
The Role of Seals
Seals serve as the first line of defense
protecting bearings from contaminants
and preserving their functionality in
harsh environments. They prevent dirt,
dust, water, and abrasive particles from
ingress. They are also critical in keeping
lubrication inside the bearings.
Design engineers should consider working
conditions when selecting bearings.
For instance, in warehouse
cading effects on the system.
* Complete Failure: It can cause misalignment
and imbalance in the system.
This can lead to a loss of positioning
accuracy, increasing the risk of
maloperation.
* Increased Friction: Failed bearings
often lead to increased friction, which
can cause overheating and reduce energy
efficacy.
Flexible ball bearings can handle radial loads and
a limited axial load. They are used in wave generators
of harmonic drive mechanisms. (Image: CCTY)
environments
dust can penetrate the bearings
- particularly in bipedal applications-
leading to a shortened lifespan or even
a complete loss of functionality. Also, if
grease exits the bearings, it can lead to
premature failure.
Seal Impact on Torque
While seals generate friction due to increased
contact, advancements in seal design
and materials mitigate these effects,
ensuring optimal performance without
compromising rotational efficiency.
Tighter seals may introduce higher
initial torque but offer better contamination
protection. Seals can have single,
double, or even triple lip designs to help
Materials
Durometer
Tensile Strength
Elongation at Break
Tear Strength
Oil Resistance
Temperature Resistance
achieve application sealing requirements.
Seals can also be molded over steel reinforcements
to strengthen their structure.
Controlling the contact between the seal
lip and the bearing surface aids in limiting
the introduced torque and can be
achieved by modifying the interference
fit between the two surfaces.
Seal Material Composition
Seals can be made from various materials,
such as rubber or synthetic polymers,
each with unique properties and
applications. Choosing the right seal
based on specific application requirements,
such as using silicone rubber for
higher temperatures, will prolong the
life of the bearing by ensuring consistent
seal performance (Table 1).
Unit NBR
Shore A
MPA
%
KN/m
-
°C
60
12.8
520
42
Good
CR
63
13.6
381
38
Adequate
-40 to 120 -55 to 120
Table 1. Comparison of material properties for seals. (Source: CCTY)
12
* Contamination: Damaged bearings can
generate metal debris which circulate
outside the bearing and cause further
damage to other components within
the system.
* Vibration: Excessive vibration is a
common result of bearing failure.
Vibration can be transmitted through
the system, leading to wear and potential
failure of other components.
Bearing failure is not isolated and
can have serious effects on the entire
system. Proper maintenance and monitoring
of bearings are essential to prevent
failure.
Collaborating with an experienced
bearing manufacturer during the initial
stages of a robotic bearing design can
establish a robust basis for the application's
performance and longevity.
This article was written by Yaman
Obaid, Mechanical Engineer specializing
in robotics for CCTY (Lake Zurich,
IL). For more information, visit
cctybearing.com/robotic-bearings.
Silicone Rubber
60
7.9
340
14.2
Good
-60 to 230
FKM
62
7
250
-
Excellent
-40 to 204
Motion Design, August 2024
http://cctybearing.com/robotic-bearings
Tech Briefs Magazine - August 2024

Table of Contents for the Digital Edition of Tech Briefs Magazine - August 2024
