The saying goes, “Learning from someone else’s mistakes is easy, but learning from your own is hard.” We hope you’ll leverage our 60-plus years of application experience to avoid some common pitfalls as you prepare to seal your next aviation, space, or defense design. Check out the short presentation we’ve prepared for you here. It dives into sealing in aviation, defense, and space equipment, and suggests ways to achieve a balance between friction and sealing effectiveness. Once you have a chance to review the presentation, let’s talk about how we can help you elevate your new or existing project.

2. Slide 2
Aviation, Space & Defense Equipment
• Aircraft & airborne systems
 Hydraulic pumps/cylinders/actuators
 Pneumatic systems
 Gimbals, pods, & pan-tilt systems
 Engines & fuel metering valves
 UAV motors & propeller shafts
• Ships & seaborne systems
 Radar tracking
 Torpedo systems
 Deep sea UUV propulsion systems
• Land/ground defense systems
 Radar/satellite
 Missile/rocket propulsion
 Hydraulic pumps/cylinders/actuators
• Space
 Rover mobility controls
 Rocket engines

3. Slide 3
Aviation, Space & Defense Equipment
• Typical operating
conditions
 Broad service temperatures
 -459°F to 600°F
 Exposure to acids, bases,
fuels, oils, & other
aggressive media
 Repetitive movements,
requiring accurate,
consistent positioning
 Long service intervals for
optimal productivity
 Subject to strict
performance standards

4. Slide 4
Seals: Critical Components
• Protect against leakage,
prevent ingress of
contamination
 Rotary/oscillating, reciprocating,
static applications
• Seal failure adversely impacts
precision, consistency,
accuracy, can cause breakdown
• Seal designs must:
 Balance friction and sealing
effectiveness to guard against
leakage while enabling smooth
operation
 Resist wear in aggressive media
 Retain sealing properties in harsh
temps

5. Slide 5
Sealing Application Examples
Actuators Fuel Metering Valves Gimbals & Pods Hydraulic Systems

6. Slide 6
Seal Properties: Impact on Design
• Friction
 Impacts power consumption
 Drives component selection
 Actuators, motors
• Sealing effectiveness
 Inhibits contamination and corrosion
 Ensures consistent performance over
time
• Durability
 No lubrication required
 Suitable for use in wet and dry
environments
• Ease of installation
 Streamlined field maintenance,
replacement

7. Slide 7
Polymer Seals
• What are they?
 Machined lip seals, made from
blended PTFE, UHMWPE, PEEK,
or other premium materials
 Most effective when combined
with a metal spring energizer
 As a machined part, can be
easily fit into desired diameter
and/or cross section
 May be enhanced with other
components (locking rings,
backup elements)

8. Slide 8
Why Polymer Seals?
• Material selection = design
flexibility
 Polytetrafluoroethylene (PTFE)
 Unfilled, virgin, modified
 Filled - graphite, carbon, glass,
polymers
 Low friction, high temperature, chemically resistant
 Ultra-high molecular weight
polyethylene (UHMWPE)
 High wear resistance (under
180 °F), best for aqueous
media
 Polyetheretherketone (PEEK)
 High temperature (to 600°F)

9. Slide 9
PTFE: An Ideal Seal Material
• Low coefficient of friction, low
“stick-slip”
 Controllable with geometries, energizers
• Wide temperature range
 -459 °F to 600 °F (-273 °C to 316 °C)
• Wide pressure range
 Hard vacuum to 20 kpsi
• Unlimited shelf life
 Performance doesn’t degrade in storage
• Excellent chemical resistance
• Superior wear resistance
 Improved with fillers
• Can seal in dry media

10. Slide 10
Seal Design Considerations
• Method of manufacture
 Machined = tighter tolerances than molded
• Geometry
 Shorter dynamic lip reduces friction
 Longer dynamic lip increases contact area
 Locking ring design retains seals through
temperature cycling and pressure
environments
• Jacket material
 Polymer-filled PTFE material
 Low friction and stiction
 Minimal wear
 Temperature range
• Seal energizer (canted coil, v-spring, helical
ribbon, elastomeric)
 Corrosion (galvanic) resistance
 Customizable loads
 Chemically compatible
 Consistent spring force with canted coil
Metal
locking
ring
PTFE
seal
jacket

11. Slide 11
Canted Coil Spring Energizer
• Unique force vs. deflection curves
• Working deflection to 35%
• Near constant spring force
 Compensates for changes to the initial
deflection caused by wear,
temperature change, tolerance
variation
• Each coil deflects independently
under load
Canted coil spring energizer

12. Slide 12
Other Factors Affecting Seal Friction
• Hardware
 Material hardness 30 Rc
min
 Smooth surface finish
 Greater sealing contact
between seal and mating
surface
 Improved sealing ability
 Reduced friction
• Seal diameter
• Lubrication
• Media type
• Pressure and speed
• Thermal cycling

13. Slide 13
Case Study: Gimbal Seal
Requirements Solutions
• Low friction and
“stick slip”
• Resistant to various
environments and
chemicals
• Bal Seal® spring-energized seal made from
PTFE material
• Low coefficient of friction and low stick-
slip
• Large temperature range
• Polymer-filled PTFE material
• Increased wear resistance
• Friction not compromised
• Large gland height
tolerances
• 1 bar of pressure
differential or less
• Bi-directional
pressure
• Flexible seal lips
• Custom-engineered seal lips
• Bal Spring® canted coil spring energizer
• Precisely control forces (within 10% of
nominal)
• Accommodates large tolerance stack-up
• Wide temperature
variations
• Large diameter
relative to cross
section
• Bal Seal® face seal profile
Spring-energized seal
lcross section with
customized, low friction
geometry

14. Slide 14
Summary & Recommendations
• Optimize your aviation, space, &
defense equipment design by choosing
seals that balance friction & sealing
effectiveness
 Consider PTFE, UHMWPE or combination of
premium polymers, fillers
 Customize seal jacket geometry to meet
specific application requirements
 Energize seal with a spring that offers
controllable force
• In early design stages, collaborate
with Bal Seal Engineering to:
 Get consultative engineering advice
 Review hardware design
 Estimate frictional outcome
 Perform Finite Element Analysis
 Produce high-quality seal prototypes
 Scale up to full production

15. Slide 15
Resources & Contact Information
marketing@balseal.com www.balseal.com +1 949.460.2100 Design request form
James Mecredy
Global Market Manager,
Aerospace & Defense
Bal Seal Engineering, Inc.
+1 949.460.2322

16. July 19 ©Bal Seal Engineering, Inc. This document contains and/or refers to PROPRIETARY information of Bal Seal Engineering, Inc., and may not be reproduced, copied,
published, or distributed in any form or disclosed to a third party, in whole or in part, without the written authorization of an officer of Bal Seal Engineering, Inc. Products are
the subject of issued or pending United States and foreign patents. Products of Bal Seal Engineering, Inc. and this document are PROPRIETARY and products may not be
manufactured, or caused to be manufactured, by any other party.
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