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Anaerobic Adhesives Usage Guide

Tuesday 8th October

KRYLEX Anaerobic Adhesive Retaining Compound KR606 KG185 KG745 KR206 KR016 KR386 KR406 KT432 KT712 KS655 KT422 KS675

Contents

Introduction to Machinery Adhesives

Retaining Compounds

Threadlockers


Machinery Adhesives

What Is A Machinery Adhesive?

Machinery adhesives are anaerobic curing liquids, pastes or gels that are used to lock, seal or bond in engineering applications.  Anaerobic adhesives are a single component acrylic resin which cures when the oxygen is removed and the product is in contact with a metalic ion such as iron or copper.  Anaerobic adhesives harden in minutes at room temperature and fully cure within 24 hours.  Anaerobic adhesives are typically used to augment the seal or holding force of a mechanically joined assembly, anaerobic adhesives are used as threadlockers, thread sealants, retaining compounds, gasket makers and flange sealants.  When designed into an assembly, these adhesives reduce component inventories, decrease total manufacturing costs, enhance equipment reliability, and minimize aftermarket breakdowns.



KRYLEX Retaining Compounds KR386 KR016 KR206 KR356 KR606 KR416 KR406 KR016 KR096 KR538-S

Retaining Compounds

KRYLEX® retaining compounds are used in the assembly of all coaxial components such as bearings, gears, shafts, bushes, pulleys, cylinder liners and rotors. They increase the load bearing characteristics of cylindrical joints, reducing assembly stresses and assembly costs.

KRYLEX retaining compounds, when cured, fill the inner space between components to provide a physical and chemical barrier that prevents fretting corrosion, oxidation and galvanic corrosion. By filling surface irregularities and clearance gaps with a hard, tough and durable acrylic polymer, the area of surface contact is increased from approximately 30% to 100% significantly improving stress distribution through the joint.

KRYLEX retaining compounds, increase the reliability of the joint, enable relaxed machining tolerences and surface finish requirements, which reduces machining costs, while helping to achieve maximum load transmission, uniform stress distribution and increased part life.


Product Category Key Characteristic Viscosity (cPs)¹ Max Gap Fill (mm) Temperature Limit Shear Strength (N/mm²)³
KR016 Retaining Compound Press Fit, General Purpose 125 0.2 150°C 21
KR206 Retaining Compound High Temperature, High Viscosity 15,000 0.4 230°C 24
KR356 Retaining Compound Slip Fit, High Strength, Slow Cure 2000 0.4 150°C 26
KR406 Retaining Compound High Temperature, Fast Cure 600 0.3 205°C 17
KR606 Retaining Compound Press Fit, Work Shaft and Housing Repair Paste 1.3 150°C 19
KR806 Retaining Compound Slip Fit, High Strength, Fast Cure 1600 0.4 150°C 26
KR386 Retaining Compound Maxiumum Strength, Permanent 2500 0.25 150°C 27
KR416 Retaining Compound Bearing Mount 600 0.25 200°C 10
KR486 Retaining Compound High Temperature, Fast Cure 600 0.2 175°C 22
KR538-S Retaining Compound Ultra High Temperature 600 0.5 1000°C 26

¹ Brookfield RVT at 25°C

³ Steel pin and collar


Traditional Assembly Methods

Interference fits (press / shrink fits) and taper fits

These rely on friction alone to transmit torque; therefore, they are limited by material, surfaces and design. Interference and press fits rely on tight machining tolerances and high precision surface finishes to obtain specific load capacities, resulting in higher production costs. Interference fitting creates additional stresses in the components that can lead to failure, particularly when combined with operational stresses.

Limitations:

Requires finely finished surfaces

Tighter machining tolerances

Requires higher quality, stronger and resistant alloys

Heating - press fitting



Keyway

These cause high stresses due to the “notch effect” that occurs.

Assembly can be difficult due to mis-alignment.

Damage to components can be caused in the assembly stage, due to “pick-up” caused by linear stress when pressing components into place.


Limitations:

Requires finely finished surfaces

Tighter machining tolerances

Axial connection

Additional machining

Key



Splines

These cause high stresses due to the “notch effect” that occurs.

Splines can also result in high machining costs and backlash between drive and overrun.

Case hardening of the surface is normally required.

Damage to components can be caused in the assembly stage, due to “pick-up” caused by linear stress when pressing components into place.

Limitations:

Requires finely finished surfaces

Tighter machining tolerances

Axial connection

Surface heat treatment (case hardening)

Additional machining of multiple splines



Relationship Between Machining Tolerences And Cost

The cost of machining decreases rapidly when tolerances are widened; for example a shaft and its bore can be machined to work effectively with anaerobic adhesives between IT (International Tolerance ISO 286) grades 6 to 8. Conventional slip, press or inteference its normaly require a much higher tolerence between IT grades 5 and 3.

KRYLEX products are effective over a very wide range of machining tolerences.


International Tolerance standard ISO 286

Showing 0% cost increase as IT Grade number decreases.

Lower number = tighter tolerance.

Graph shows between 10 and 30% reduction in component cost by widening machine tolerances and allowing the use of anaerobic adhesives.



Relationship Between Surface Finish And Cost

Surface finish is an important cost factor in time and material, to achieve fine finishes, heat treatment, grinding or honing may be required to achieve the required load capacity.

KRYLEX products do not need a highly finished surface as the liquid, paste or gel lubricates and fills surface irregularitiesincreasing the actual mating surface area to 100%.

KRYLEX Retaining compounds benet from a recommended surface roughness of 1.6 to 3.2 µm Ra. Smoother surfaces will reduce mechanical interlock and affect the strength of the bonded joint, rougher surfaces increase the risk of misalignment when assembled.


Surface Finish (based on Ø30mm shaft)

Showing cost increase for finer surface finish requirements.  Cost increase is also proportional to component diameter.

Larger diameter = increased cost

Lower number = finer finish

Graph shows significant reduction in component cost by the use of rouger surface finishes and allowing the use of anaerobic adhesives.


Selecting The Correct KRYLEX Grade

There are four key factors need to be considered when determining the most suitable retaining compound for a project.

1) Gap size between parts. Typically, low-viscosity products are only suitable for gaps up to 0.15mm.

2) Temperature resistance. Most KRYLEX anaerobic adhesives withstand temperatures up to 150 °C, however KR206 will withstand temperatures up to 230 °C.

3) Shear strength of the product. This is governed by whether you need a permanent bond or the ability to dissemble the part in the future for maintenance.

4) Cure speed. Will you need to make adjustments after the part has been assembled?


Items Requiring Disassembly For Maintenance

Items such as bearings and oilite bushes which need subsequent disassembly, require the use of a product with a Iower final bond strength i.e. KRYLEX KR416.


Items Requiring A High Strength Bond

For items that require a high strength but not permanent bond, i.e pulleys, gears, rotors and keyways, select a product with a shear strength between 19-26 N/mm².  For disassembly, heating of the components with an ovenmay be required to break the adhesive bond.


Worn Parts Or Items With Larger Clearance

For items requiring additional gap filling capacity, a higher viscosity grade is recommended. KRYLEX grades KR206, and KR606 are ideal for this application.


Items Requiring A Permenant Bond

For items requiring maximum bond strength i.e liners, sleeves, select a product with a shear strength 27 N/mm² or higher.  KRYLEX grade KR386 is perfect for this application.


Items Requiring A Slower Cure

For items requiring alignment after assembly or with a large engagement area, select a product with a slower curing speed. KRYLEX grade KR356 has a slower cure speed to allow for complex assemblies and alignment issues.




 

KRYLEX Threadlocker KT702 KT622 KT712 KT772 KT422 KT432 KT722 KT0222

Threadlockers 

KRYLEX threadlockers provide superior reliability over mechanical locking devices in the assembly of threaded fasteners at a lower overall cost. The anaerobic liquid is applied to the threads of a fastener and cures into a hard,thermoset plastic-locking the assembly together and preventing unwanted movement, leaking and corrosion.

KRYLEX threadlockers, when cured, form polymer chains that adhere to every tiny imperfection in the threads. The adhesive completely fills the microscopic gaps between adjacent threads to positively lock and seal all types of threaded assemblies, preventing lateral movement and protecting the joint from corrosion.

KRYLEX threadlockers are highly reliable, low-cost materials that improve torque control, reduce galling and provide additional lubricity during assembly. Available in various strengths for use in a wide range of applications, KRYLEX threadlockers, over rapid cure, high shear strength, good vibration, environmental and chemical resistance.

KRYLEX threadlockers outperform mechanical locking techniques such as special washers, nuts or pins.


Product Category Key Characteristic Colour Viscosity (cPs)¹ Temperature Limit

Torque Break/Prevail

(N.m)²

KT0222 Threadlocker Low strength, Small fasteners to 6mm Purple

3000

 150°C  8/3
KT422  Threadlocker Medium strength, Bolts 6mm to 19mm  Blue  1200   150°C 17/11 
KT432  Threadlocker  Medium strength, Oil tolerant  Blue  7000   150°C 19/10 
KT622  Threadlocker  High strength, Fasteners to 19mm  Blue  4000   150°C 25/15 
KT702  Threadlocker  High strength, Permanent  Green  500   150°C 34/40 
KT712  Threadlocker  High strength, Fasteners to 25mm  Red  500   150°C 40/40 
KT722  Threadlocker  High strength, High temperature  Red  15,000   230°C 26/26 
KT772  Threadlocker  High strength, Fasteners >25mm  Red  7000   150°C 40/40 
KT902  Threadlocker  Medium strength, Wicking grade  Green  10   150°C 21/44 

¹ Brookfield LVT/RVT at 25°C

² M10 black oxide steel bolt and M10 bright steel nut


Traditional Locking Methods

Castellated Nuts and Pins

A castellated nut, sometimes referred to as a castle nut, is a nut with slots (notches) cut into one end. This is tightened
onto the thread until the specified torque is reached, a hole is drilled through the thread in line with one of the slots,
then a cotter pin, R-clip or safety wire is inserted through the hole to secure the nut. This positive lock prevents the nut
from turning and loosening.

Limitations:

Requires additional components

Hole through thread weakens threaded section

Difficult to achieve correct torque and alignment

No corrosion protection


Locknut 

Locknuts are normally 50% of the width of a normal nut. The locknut is assembled onto the thread and tightened into position. The full width nut is then tightened down onto the locknut. This has the effect of reversing the stress on the locknut as the threaded component strains. This is a friction locking principle.

Limitations:


Additional special half-width nut

Additional tightening operations

Not particularly secure under high vibration loads

No corrosion protection


Shakeproof and Spring Washers 

These are low cost items with questionable reliability generally considered only suitable for non-critical consumer items. The shakeproof washers are generally made from spring steel with serrations either on the inside or the outside diameter which grip the adjacent surfaces. The spring washers prevent rotation of the nut or bolt by digging into the surface of the two adjacent faces.

Limitations:


Damages adjacent surfaces

Not particularly effective on dynamic loads

Single use

No corrosion protection


Tab Washers 

These are simple, stable and reliable methods of ensuring that lock nuts remain fastened. Tab Washers take the form of plain washers with one or more tabs which can be bent to provide a mechanical lock. The washer is placed under the nut and the nut tightened. These tabs are designed to be bent at 90° one tab into a locating hole, the other tabs flat against the sides of the nut. This positive lock prevents the nut from turning and loosening.

Limitations:

Requires additional machining

Single use

Time consuming

No corrosion protection



Locking Plates
 

These are another simple, stable and reliable method of ensuring that locknuts remain fastened. Like tab washers they are placed under the nut, then fastened in place with a locking screw. The nut is tightened then the sides of the plate are bent to sit against the sides of the nut similar to tab washers. This positive lock prevents the nut from turning and loosening.

Limitations:

Requires additional machining

Time consuming

Single use

Requires additional locking screw

No corrosion protection



The KRYLEX Way

Threadlocking Fluid, Gel or Paste

One size fits all solution. Lock against vibration, shock and thermal cycling – plus seal against corrosion and galling.  Outperform locking devices - Better load retention compared to all mechanical locking devices.


Advantages:


Universally applicable "one size fits all"

Easy to use

Lower cost per unit

Requires no additional / special components

Protection against corrosion



Selecting the Correct KRYLEX Grade

There are four key factors need to be considered when determining the most suitable threadlocker for a project.

1) Thread size and pitch. Typically, as the thread size and pitch increases a higher viscosity product with increased gap filling capacity is required.

2) Temperature resistance. Most KRYLEX anaerobic adhesives withstand temperatures up to 150 °C, however KT722 will withstand temperatures up to 230 °C.

3) Strength of the product. This is governed by whether you need a permanent bond or the ability to dissemble the part in the future for maintenance.

4) Material. Also take into account the component material. Non-ferrous materials with a lower tensile strength require the use of lower strength threadlocking products.


Items Requiring Disassembly For Maintenance / Non-ferrous materials

Items such as non-ferrous screws and small threaded components <6mm or items which need subsequent disassembly, the use of a product with a Iower final bond strength is recommended i.e. KRYLEX KT0222. The type of metal used on the fastener also is critical to the performance of the adhesive. If the fastener is made of two inactive metals such as stainless steel, zinc, magnesium, black oxide, cadmium, anodized aluminum or passivated titanium, then KRYLEX KP6497 primer may be used to initiate the curing.


Items Requiring A Medium Strength Bond

For threaded components up to 25mm that require a medium strength bond, allowing the removal with simple hand tools, select a product with a breakaway torque between 15-20 N/m.


Items Requiring A Permenant Bond

For items requiring maximum bond strength i.e cylinder head studs, select a product with a breakaway torque 25 N/m or above. KRYLEX grades KT702, KT712, KT772 and KT902 are all suitable this type of application.


Threadlocking Post Assembly

For items that have already been assembled, a very low viscosity penetrating threadlocker may be used. KRYLEX grade KT902 high strength threadlocker is designed to wick into preassembled fastener threads by capillary action.


Source: KRYLEX, a Chemence® brand