Product details
| Grade | Loctite 660 |
| Strength | High strength |
| Colour | Silver-grey paste |
| Family | Retaining compounds |
| Brand | Loctite (Henkel) |
| Stock | Held in Dubai — buy one or bulk |
Pack sizes
Prices on request. Tell us the quantity you need.
Check stockWhat Loctite 660 is for
The salvage grade. Where every other retaining compound needs a reasonably close fit, 660 bridges gaps approaching 0.5 mm — twice what 638 will handle — so a worn shaft, a spun bearing or a damaged keyway can be put back into service without re-machining. It is a metallic grey paste rather than a liquid, thick enough to stay in a large clearance instead of running out of it.
Key features
- Gaps approaching 0.5 mm — the largest in the retaining range
- Restores worn shafts, spun bearings and damaged keyways without re-machining
- Excellent gap cure characteristics
- ≥17.2 N/mm² compressive shear
- Metallic grey paste — stays in a large clearance
- NSF registered Category P1 for food processing areas (a regional approval)
- Full strength retained in motor oil at 125°C and unleaded petrol to 1,000 hours
- Cures down to 4°C
Typical applications
- Worn keyways
- Oversized bores
Technical data
Uncured material
| Technology | Acrylic |
| Chemical type | Urethane methacrylate |
| Appearance | Metallic grey paste |
| Fluorescence | No |
| Components | One component — no mixing |
| Cure | Anaerobic; secondary cure by activator |
| Viscosity, Brookfield HBT 25°C | Spindle TB at 0.5 rpm, Helipath: 1,000,000–2,000,000 mPa·s |
| Viscosity at 5.0 rpm, Helipath | 150,000–350,000 mPa·s |
| Viscosity class | High |
| Specific gravity at 25°C | 1.13 |
Strength
Steel pins and collars after 24 hours at 22°C.
| Compressive shear strength (ISO 10123) | ≥17.2 N/mm² (2,490 psi) |
| Maximum gap | Approaching 0.5 mm (0.02 in) |
| Elongation at break (ISO 37) | <2% |
| Cure graphs published at gaps of | 0.154 mm and 0.27 mm |
| Cures down to | 4°C |
Chemical resistance
As a percentage of initial strength after ageing.
| Environment | °C | 100 h | 500 h | 1,000 h |
|---|
| Motor oil (MIL-L-46152) | 125 | 100% | 100% | 100% |
| Unleaded petrol | 22 | 100% | 100% | 100% |
| Ethanol | 22 | 95% | 95% | 95% |
| Water / glycol 50:50 | 87 | 100% | 90% | 80% |
| Brake fluid | 22 | 80% | 75% | 75% |
| Acetone | 22 | 80% | 80% | 80% |
Cured material
| Coefficient of thermal expansion (ISO 11359-2) | 80 × 10⁻⁶ K⁻¹ |
| Thermal conductivity (ISO 8302) | 0.1 W/(m·K) |
| Specific heat | 0.3 kJ/(kg·K) |
| Heat ageing data published at | 120°C and 150°C |
How to use it
- Clean all surfaces, external and internal, with a Loctite cleaning solvent and allow to dry.
- On inactive metals, or where large gaps are present, use an activator and allow to dry.
- Slip fits: apply around the leading edge of the male part and the inside of the female part, and use a rotating motion during assembly to spread it.
- Press fits: apply thoroughly to both surfaces and assemble at high press-on rates.
- Shrink fits: coat to a smooth even film. Heating the female part — coat the male. Cooling the male part — coat the female. Doing both — apply to the cooled part, and avoid condensation on it.
- Shrink fits: coat the pin, then heat the collar to create enough clearance for free assembly.
- Do not disturb the parts until handling strength is reached.
Handling and storage
- Not recommended for pure oxygen or oxygen-rich systems.
- Not a sealant for chlorine or other strong oxidising materials.
- Not normally recommended on plastics — thermoplastics can stress-crack.
- Disassembly: hand tools first; if needed apply localised heat to about 250°C and take apart while hot. If that temperature is not possible, heat as far as you can and use mechanical aids.
- Store unopened and dry, ideally 8°C to 21°C; outside 8–28°C the properties can be affected.
- Do not return decanted product to the original container.
When 660 rather than 638?
Measure the clearance. Up to about 0.25 mm, 638 is stronger at 29 N/mm² and is the better choice. Beyond that — a shaft that has worn oversize, a bearing seat that has spun, a keyway that has hammered out — only 660 will bridge it, and it does so at ≥17.2 N/mm² without sending the part to the lathe. For gaps larger than 0.5 mm, an anaerobic is the wrong tool: use a metal-filled epoxy such as Loctite 3471 or the Devcon range.
Always read the current technical and safety data before use —
ask us and we'll send it with your quotation.
