Retaining compounds increase the strength and reliability of traditional press and shrink fits. Retaining compounds improve the distribution of stress, which increases maximum load transmission and performance. They create a physical barrier that eliminates fretting, oxidation and galvanic corrosion, which increase service life. Recent chemical advances in retaining address assembly process variables including gaps, surface finish and cleanliness ensuring consistent performance. Application equipment provides repeatable precision dispensing. • Recent innovations in retaining: tolerance, higher temperature resistance, primerless formulas • New data on retaining advancements: test results on strength, oil and chemical tolerance • How to use retaining compounds to augment a press fit for increased reliability • Application case histories for retaining including cost and performance

1. Increasing the Strength and Reliability
of Press Fits

2. Before We Start
 This webinar will be available afterwards at
designworldonline.com & email
 Q&A at the end of the presentation
 Hashtag for this webinar: #DWwebinar

3. Moderator
Presenter
Q&A
Miles Budimir
Doug
Lescarbeau
Robert Dunkel
Design World
Henkel-Loctite
Henkel-Loctite

4. Increasing Strength &
Reliability of Press Fits
Doug Lescarbeau
Anaerobic Technology Director, Henkel Corporation
Robert Dunkel
Technical Service Director, Henkel Corporation
November 14, 2013

5. Agenda
• Mechanical retaining
• Retaining compounds
• Performance
• Application process
• Disassembly
• Recent innovations
• Application case histories

6. Mechanical Retaining Methods
There are three common mechanical methods used to join cylindrical
components such as gears, bearings, shafts and hubs:
Types of Fits
Mechanical-Drive
Assembly
Interference Fit
Assembly
Tack in Place
Assembly

7. Mechanical Drive Assemblies
Set Screw
Pin
Keyway
Spline Shaft
The most common mechanical-drive assembly is the conventional key/keyway.
Other mechanical-drive assemblies are set screws, pins and spline shafts.
All transmit torque levels related to their mechanical interlocking:
Set screw << pin << keyway << spline shaft
All are easy to assemble or disassemble.

8. Mechanical Drive Limitations
• Notch effect creates high stress
concentration in the area of the
screw, key, pin or spline.
• Backlash, inherent in most
designs, results in relative
movement leading to abrasive
wear
• High machining costs result due to
additional manufacturing steps
• Uneven distribution of mass will
affect balance

9. Interference Fit Assemblies
D1 >> d2
d>D
e.g. H7/k6
Press Fit
Taper Fit
Shrink Fit
Press fit: interference is created because the shaft is larger in diameter than the
hole into which it is pressed.
Taper fit: interference is created when the fastener is tightened so the parts are
drawn together.
Shrink fit: The hub is expanded with heat or the shaft is shrunk with cold before
parts are assembled. Interference is created when parts return to normal
temperature.

10. Limitations of interference fit assemblies, e.g.
taper fits, press fits, shrink fits
• Material, surface and design restrictions rely on
friction alone to transmit torque
• Close tolerances required to achieve specific load
capacity results in high machining costs
• Micro-movement can cause fretting corrosion that
will accelerate wear and increases the risk of part
failure
• Surface galling makes disassembly difficult/
impossible
• High stress in components, due to interference fits,
plus operational loads can lead to part failure

11. Tack in Place Assemblies
Connections by welding or soldering
are high strength assemblies, but
complete load is carried by the small
welding area.

12. Limitations of welded or soldered tack in place
assemblies
• Only compatible metals can be joined
• Heating of the material can create distortion,
residual stresses and structural degradation in
welded areas.
• Disassembly difficult/impossible
• Additional costs due to need for specialized
equipment, e.g., laser welding, energy
• Need for specially trained personnel, e.g., Welders
• Welding usually requires secondary cleaning and
grinding operations.

13. Retaining Compounds
• Single component adhesive
• Fill gap between joined parts
• Make use of complete contact
area
• Good adhesion to metal surfaces
• High cohesion of the adhesive
layer
• Provide high shear strength

14. Retaining Compound Options
Augment Mechanical Retaining
• Higher load transmission and better
performance with existing designs and
geometry.
• Equal performance with relaxed tolerances.
• Reduce the size and weight of an assembly.
Replace Mechanical Retaining
• High-strength products can carry high loads.
• Because there is 100% contact, load and
stress is distributed evenly over the joint.
• All voids are filled, which prevents corrosion
and fretting.

15. Design Tools
Proprietary RetCalc+ software models Retaining Compound performance
Input
• 6 Joint Design Factors
• 3 Retaining Compound Factors
Output
• Axial load rating
• Torque rating

16. Cost Benefits
• Reduce or eliminate expensive machining
operations.
• Eliminate some surface finishing requirements.
• Prolong equipment life through better fatigue and
corrosion resistance.
• Fill gaps so machining tolerances can be widened.
• Help lower overall assembly and maintenance
costs.
• Simplify assemblies by reducing use of circlips,
keys, dowels or threads.
• Can eliminate the need for mechanical retainers.
• Minimize machine downtime, ensuring an earlier
return to service.

17. Retaining Compounds
Comparison to Mechanical Assembly Methods
Retaining Compounds:
• Increase assembly reliability.
• Produce more accurate, rigid assemblies.
• Eliminate backlash in keys and splines.
• Prevent small diameter shaft distortion.
• Increase strength of mechanical retaining
methods.
• Eliminate fretting corrosion.
• Seal against environmental corrosion.
• Eliminate high assembly stresses.
• Reduce variations in load transmission.
• Allow dissimilar materials to be assembled more
easily.
Interference (press fits or shrink) fits and taper fits
• Rely on friction alone to transmit torque; therefore, they are limited by
material, surfaces and design.
• Close tolerances are needed to obtain specific load capacities, leading
to higher production costs.
• Interference fitting creates stresses in the components that can lead to
failure, particularly when combined with operational stresses.
Keyway and spline assemblies
• Cause high stresses due to the “notch effect” that occurs.
• Result in high machining costs and backlash.
Welding and soldering
• Only compatible metals can be joined.
• Heating of the material can lead to residual stresses and structural
degradation and distortion.
• Requires skilled labor and secondary cleaning and grinding.

18. Application Process
Dispensing Equipment provides process control
Manual
Semi-Automatic
Automatic

19. Disassembly
Bearings assembled with Retaining
Compound can be disassembled with
industry standard bearing disassembly
tools and techniques, including bearing
pullers and hydraulic presses.
Another technique is to heat the parts well
above the service temperature [to 250°C
(482°F) for most products] and
disassemble while the parts are hot.

20. Voice of Customer & Market Research
• Market research identified improvement opportunities
• Performance
• Primerless
• Oil Tolerant
• Higher Temperature
• Selection
• Simplify selection
• Global product range

21. Innovation
Temperature upgrade
•
•
Upgraded Temperature to 360ºF (180ºC)
Improvements measured via heat aging

22. Innovation
Oil Tolerance
•
Tested on steel pins and collars with light contamination

23. Innovation
Primerless
•
Improved performance on all materials

24. Innovation
Primerless
•
Improved strength development thru gap

25. Innovation
Performance summary
Retaining components are often inactive surfaces.
Primerless simplifies the assembly process.
Health and safety has changed industry cleaning procedures.
Oil tolerant delivers more consistent strength.
Smaller, higher power components operate hotter
Higher 180oC (360oF) rating withstands the temperature

26. Selection
• Five products
• Globally available

27. Applications

28. Electric Motor Assembly
Situation
US motor manufacturer
wanted to improve brushless
motor assembly
Solution
Parts slip together and are bonded in place with a
retaining compound.
Challenges
• Assembly is subject to high
torsional stresses
• Must resist lubricating oils
Benefits
• Retainer increases strength
• Relaxed tolerances reduced part cost
• Slip fit simplifies component alignment versus press fit

29. Wheel Suspension Shaft Coupling
Situation
Solution
Urban public transport company in
Belgium needs to secure pins for
the wheel suspension.
Challenges
The pin in the hole has too much
tolerance so it is susceptible to
corrosion and wear.
Benefits
• Cost savings. Pins last 400,000 km instead of 100,000 km
• Corrosion is prevented
• Retainer distributes stresses providing highly reliable bond
• Robust process. Performs even if parts have light oil contamination

30. Heat Exchanger Assembly
Situation
Heat exchanger tube repair
required time consuming and
costly.
Challenges
• Must withstand refrigerant
fluid and thermal environment.
Benefits
• Faster process than brazing
• Bonding, unlike brazing,
does not require skilled labor
Solution
Heat exchanger tubes are inserted into the tube sheet
using a slip fit with retaining compound applied to the
outer diameter of the tube.

31. Threaded Inserts
Situation
A manufacturer of large air
bearings wanted to eliminate
spot welding threaded inserts.
Solution
Inserts are bonded into place with a retaining
compound. No cleaning or priming required.
Challenges
• Parts have an have oily film
• Must be ready for further
processing within minutes
Benefits
• Lowered production cost
• Eliminated hazardous fumes emitted during welding galvanized
• Reduced work in process and plant floor space for process

32. Athletic Prosthetic Leg and Foot
Situation
Prosthetic equipment maker
needs to secure bearing for
competitive sports equipment.
Solution
Bushings and stainless steel bearings are coated with
retaining compound, then press fit into place.
Challenges
• Repetitive high impact conditions
• Thermal cycling from weather
extremes
• Durability to protect athlete
Benefits
• Joint strength is increased because retainer augments strength of press fit
• Retainer provides 100% contact which distributes stresses, improves reliability
• Bearing assembly seats are sealed preventing corrosion

33. Thank you!
As a thank you
for participating
in the webinar,
you’ll receive a
free copy of the
Retaining
Compound
Design Guide in
the mail.
www.loctiteretaining.com

34. Questions?
Henkel-Loctite
Design World
Miles Budimir
mbudimir@wtwhmedia.com
Phone: 440.234.4531
Twitter: @DW_Motion
Doug Lescarbeau
doug.lescarbeau@henkel.com
Henkel-Loctite
Robert Dunkel
Robert.dunkel@henkel.com

35. Thank You
 This webinar will be available at designworldonline.com & email
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