Retaining compounds
High strength, low-viscosity bonding - high temperature resistance
This low viscosity, high strength, anaerobic-curing retaining compound is designed for bonding cylindrical fitting parts. Even works on slightly oily surfaces e.g. from various oils, such as cutting fluids.
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- Description
- Technical specification
- Rating & reviews
- Question & answer
When you’re working with holding gears and sprockets on gearbox shafts, or rotors on electric motor shafts, LOCTITE® 648 is ideal for preventing loosening and leakage from shock and vibration. This green, low viscosity, high strength, anaerobic-curing retaining compound provides reliable bonds of cylindrical assemblies, even when exposed to high temperature environments. It cures on active metals (e.g. mild steel) as well as passive substrates like stainless steel and plated surfaces, and it even tolerates minor surface contaminations from oils such as cutting, lubrication, anti-corrosion and protection fluids without the use of a primer or cleaner.
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Works on active and passive substrates without primer
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High strength and oil resistance
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Temperature resistant up to 180°C (355°F)
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Fluorescent under UV for quality control
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Low viscosity
- Product category:
- Retaining compounds
- Technologies:
- Acrylates, anaerobic cure
- Agency approvals / certificates / specifications:
- DVGW (EN 751-1): NG 5146C00236,NSF P1 Reg. No 148350,WRAS (BS 6920): 0808532
- Color:
- Green
- Fixture time:
- 3.0 min.
- Gap fill:
- 0.15 mm
- Key characteristics:
- Oil tolerant,Strength: high strength,Temperature resistant
- Operating temperature:
- -55.0 °C - 180.0 °C (-65.0 °F - 355.0 °F)
- Recommended for use with:
- Metal: steel
- Shear strength, Steel:
- 27.0 N/mm² (3900.0 psi)
- Viscosity:
- 500.0 mPa·s (cP)
How to use
Use LOCTITE® 790 for easier removal of old adhesive residues. It is recommended to use LOCTITE® 7070 to degrease and clean surfaces prior to applying the adhesive.
If cure speed is too slow due to passive metals or low temperature (below 5°C), use activator LOCTITE® SF 7649 (see cure speed vs activator graph in the TDS). Allow to dry.
Apply adhesive around the leading edge of the male component and the inside of the female component. Assemble parts with a rotating motion to ensure good coverage. Wipe off excess adhesive
Apply 360 degree beads of adhesive to both bond surfaces at the leading edges of insertion or engagement, and assemble at high press-on rates. Wipe off excess adhesive.
Apply the adhesive onto the male component; heat the female component to cause expansion for free assembly. Assemble components and allow temperatures to equilibrate. Wipe of excess adhesive.
Apply localized heat to approximately 500°F/260°C; disassemble while hot. For corroded or seized parts, use LOCTITE® 8040 Freeze and Release.
For manual assembly of adhesive, the use of LOCTITE® Pro Pump Handheld Dispenser (50ml/250ml) or LOCTITE® Peristaltic Hand Pump is recommended to ensure a consistent application volume. For semi-automatic or fully-automated dispensing options, contact our technical service team for advice.
For gaps larger than 0.5mm or for worn out shafts, bearing seats or keyways, use LOCTITE® metal-filled compounds or LOCTITE® 660 Retaining Compound.
FAQ
Even in the best-press-fit application (mechanical) there is only 20% to 40% actual metal contact between the surfaces – leaving gaps between fitted parts which cause cylindrical assembly failure. LOCTITE can achieve 100% contact by filling the gap completely: by filling all the voids between the parts we increase the overall strength of the assembly by up to three times that of the original press fit. Thus, retaining compounds secure bearings, keyways and cylindrical parts into housings or onto shafts, forming strong assemblies. Making it an effective and economical method to eliminate challenges like loosening, corrosion backlash and wearing by unitizing the assembly and provide uniform stress distribution. In a nutshell: Benefit of use Adhesive Solutions vs. Alternatives: - Adhesive Solution: Retaining Compounds fill the inner space between the components and cure anaerobically to form a strong unitized assembly. Once cured, RCs provide high shear strength with maximum load transmission capability and uniform stress distribution, while also eliminating fretting corrosion They improve reliability, eliminate failures, and reduce overall costs in customer operations. - Mechanical: Conventional assembly methods include pins, key/keyway assemblies; splines; clamp rings, press fits, shrink fits, taper fits; welding and soldering. These methods often require special machining, resulting in costly and time-consuming assembly procedures, and do not uniformly distribute the load forces, which can result in premature wear and failure of the assembled components.
Yes, LOCTITE® anaerobic retaining adhesives become highly resistant thermoset polymers once cured, making them suitable for a vast number of applications. Consult the online product resources or contact our technical teams for further information.
Product selection is specific to each application. As a rule of thumb, thinner/low viscosity products are used for tighter fitting parts with low diametrical clearance; thicker/high viscosity products are used where gap-filling capability is needed. Bonded heat shrink-fit assemblies will utilize a low viscosity product with high thermal resistance, e.g. LOCTITE® 648. For slip-fitted assemblies, apply to the leading edge of the male part and female parts. Assemble with a twisting motion. For press-fitted assemblies, apply adhesive generously to both bond surfaces and assemble with a high press on rate. For shrink fitted assemblies, apply adhesive to the shaft, and heat the collar to create sufficient clearance for free assembly.
The standard continuous operating temperature range for LOCTITE® anaerobic adhesives is -65°F to 300°F (-55˚C to +150˚C). Depending on the specific application requirements, high-performance grades are also available offering increased temperature resistance. We call out if one of our retaining compounds meets higher temperature resistance. You may also contact us to more consultation.
Yes, all LOCTITE® anaerobic adhesives will lock and seal components and assemblies, preventing failure from vibrational loosening and corrosion.
There are several factors which will affect the cure speed or fixture time of LOCTITE® anaerobic adhesives - most notably the substrate material, the bond gap and the application temperature. Anaerobic adhesives cure by the chemical reaction with active metal ions (specifically iron or copper) and the exclusion of air within small gaps to cure. If the substrates are passive (low iron or copper content), or the ambient temperature is low, the cure reaction may be slow. In these circumstances an activator can be applied to the substrate prior to bonding to speed up the reaction. Alternatively, the components can be heated to speed up the reaction and reduce the fixture and cure time. Please see more details on the relevant technical data sheet.
Some LOCTITE® anaerobic adhesives - LOCTITE® 648 is one of them - have been formulated to be tolerant to light oil contamination of parts, allowing for immediate application and eliminating additional cleaning processes in some applications. Contamination levels may vary. Excessive contamination and using an adhesive which is not oil tolerant will reduce the strength and overall success of a bonded assembly. Please speak to Henkel's technical team for information and guidance.
If the parts cannot be separated using mechanical methods alone, we recommend applying localized heat to the components for several minutes before applying force. Long-term exposure to temperatures more than 500°F/260°C will start to degrade the adhesive and can aid disassembly.
