When specifying a coupling for a mechanical system, many factors are involved in the decision. Andy Lechner of R +W America, Ross Rivard of Ringfeder and Bobby Watkins of Ruland Manufacturing Co. will each take some time to help us gain a better understanding of when the different types of couplings make the most sense for an application.
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q This webinar will be available afterwards at
www.designworldonline.com & email
q Q&A at the end of the presentation
q Hashtag for this webinar: #DWwebinar
Before We Start
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Mike Santora
Associate Editor -
Moderator
Design World
Edward Cole
Engineering Manager
Ringfeder Power
Transmission USA Corp.
Andy Lechner
Product Manager
R+W America
Flexible vs. Rigid Couplings
Bobby Watkins
Vice President of Sales
Ruland Manufacturing Co. Inc.
Meet the speakers…
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Servo Coupling Requirements!
• Backlash-free to maintain positioning accuracy.
• Mass balanced for high rotational speeds.
• Designed for low to moderate torques—usually to 100 Nm.
• Tolerant of shaft misalignments.
• Maintenance free.
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Servo Coupling Applications!
• Any automation system with shaft-driven linear motion, including:
• Machine tools.
• Packaging equipment.
• Test and measurement systems.
• Semiconductor manufacturing.
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Servo Coupling Choices!
• Two types of servo couplings can meet these requirements:
• Rigid metal bellows couplings.
• For example, Ringfeder Gerwah EKN and DKN Series.
• Flexible servo insert couplings.
• For example, Ringfeder Gerwah GWE Series.
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Servo Coupling Choices!
• Many servo applications do not strongly favor one type of coupling over another.
• Either a metal bellows and servo insert coupling can satisfy basic torque, shaft size and
lifecycle requirements.
• But each type of coupling has its subtle advantages:
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Metal Bellows Coupling!
• Typically constructed of stainless steel bellows with aluminum hubs.
• Integrated clamping hubs or set screws in miniature models.
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Servo Insert Coupling!
• Typically consists of aluminum hubs and elastomer “spider” inserts.
• Clamping via set screws or integrated clamping hub
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• Adjustable flexibility by changing elastomer inserts.
• Harder inserts approach metal bellows stiffness.
• Softer inserts maximize damping and misalignment tolerance.
• Optimize vibration damping through insert selection.
• Excellent tolerance of radial, axial and angular misalignment.
• Good torque transmission and angular positioning performance.
Servo Insert Coupling!
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• Keep in mind that servo couplings often work in conjunction with other power
transmission components, such as gear boxes and linear actuators.
• It’s important to choose couplings whose
designs work well with related
power transmission components.
• Shrink discs
• Locking assemblies
Couplings Are Part Of A System!
35. #DWwebinar Presented by: Bobby Watkins www.ruland.com
Backlash, Windup, and Bearing Loads
Coupling with Windup • Windup is not backlash
• Backlash refers to power transmission error
• Windup is posi>on error without torque error
• All couplings have windup
• Zero-backlash means zero loss in power
transmission
• Bearing loads increase wear
• Excessive bearing loads result in bearing wear
and
• premature failure
• Couplings designed to flex during misalignment
produce bearing load
• Coupling misalignment ra>ngs oNen result from
bearing loads
Coupling with Misalignment
36. #DWwebinar Presented by: Bobby Watkins www.ruland.com
Bearing Loads
• Misalignment exists between
the motor and the driven system
due to tolerances and/or system
incompa>bility
• Bearing loads are generated as a
result and are harmful to system
performance
• Other system design factors
must be considered when
selec>ng a coupling
37. #DWwebinar Presented by: Bobby Watkins www.ruland.com
Managing Misalignment
• Selec>on of the correct coupling
is cri>cal
• Must address the applica>on
misalignment type or types
• Must stay within the coupling
specifica>ons
• Must install the coupling
properly
• Other applica>on criteria must
also be addressed
38. #DWwebinar Presented by: Bobby Watkins www.ruland.com
Rigid Couplings
Benefits
• Best torque transmission capabili>es
• Almost zero-windup = the most precise coupling
available
• Suitable for shaN support and push-pull applica>ons
• Low cost
Drawbacks
• No misalignment capabili>es
• No allowance for thermal expansion
• Extremely high bearing loads if used incorrectly
• Poten>al for damage to system components
• Very high iner>a - not suitable for high RPM applica>ons
39. #DWwebinar Presented by: Bobby Watkins www.ruland.com
Flexible Couplings
Benefits
• Accommodate misalignment
• Different styles allow the user to select the best fit for
the applica>on
• High RPM capabili>es
• Many standard size op>ons are available
• Most have low iner>a
Drawbacks
• Some require maintenance
• Installa>on can require specialized alignment systems
• Limited torque capabili>es
• Both shaNs must be bearing supported
• High cost
Oldham Coupling Bellows Coupling Beam Coupling Jaw Coupling Disc Coupling
40. #DWwebinar Presented by: Bobby Watkins www.ruland.com
Product SelecFon
• Mul>ple solu>ons may exist when
selec>ng a coupling
• Specific couplings are beser suited
for each type of misalignment, for
example: oldhams with parallel
misalignment or beam couplings for
angular misalignment
• Bearing loads and windup are a side
effect of all couplings
• Proper coupling selec>on requires a
full understanding of the system
requirements
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Mike Santora
Associate Editor -
Moderator
Design World
@DW_MikeSantora
Edward Cole
Engineering Manager
Ringfeder Power
Transmission USA Corp.
Edward.cole@ringfeder.com
Andy Lechner
Product Manager
R+W America
Alechner@rw-america.com
Flexible vs. Rigid Couplings
Bobby Watkins
Vice President of Sales
Ruland Manufacturing Co. Inc.
Robert.watkins@ruland.com
Questions?
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Thank You
q This webinar will be available at
designworldonline.com & email
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