Product details
| Grade | Loctite 648 |
| Strength | High strength |
| Colour | Green |
| 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 648 is for
The strongest retaining compound in the range at 31 N/mm², and the one Henkel recommends for bonded shrink fits — low viscosity with high thermal resistance, so it survives the heat of assembly. It cures on passive substrates including stainless and plated surfaces, tolerates cutting and anti-corrosion oils, and has a glass transition of 100°C against 76°C for 638. Typical work: gears and sprockets onto gearbox shafts, rotors onto motor shafts.
Key features
- Highest strength in the range — 31 N/mm² on steel, 30 on stainless
- 13.5 N/mm² after 15 minutes
- Glass transition 100°C; heat ageing data to 200°C
- Henkel's recommendation for bonded heat shrink-fit assemblies
- Cures on stainless and plated surfaces; tolerates light oil contamination
- Gaps approaching 0.15 mm
- Gains strength in service: 165% in motor oil, 140% in brake fluid, 130% in petrol
- Cold strength tested to −75°C
Technical data
Uncured material
| Technology | Acrylic |
| Chemical type | Urethane methacrylate |
| Appearance | Green liquid |
| Fluorescence | Positive under UV light |
| Components | One component — no mixing |
| Cure | Anaerobic; secondary cure by activator |
| Viscosity, Brookfield RVT 25°C | Spindle 2 at 20 rpm: 500 mPa·s |
| Viscosity, cone & plate 25°C | 500 mPa·s at 129 s⁻¹ |
| Viscosity class | Low |
| Specific gravity at 23°C | 1.1 |
Compressive shear strength (ISO 10123)
Cured at 23°C.
| Substrate and cure | N/mm² (psi) |
|---|
| Steel pins and collars, 15 minutes | 13.5 (1,960) |
| Steel pins and collars, 72 hours | 31 (4,480) |
| Stainless steel pins and collars, 72 hours | 30 (4,350) |
| Aluminium pins and collars, 72 hours | 18 (2,610) |
Torque performance
Cured 72 hours at 23°C, ISO 10964.
| Fastener | Breakaway N·m (lb·in) | Prevail N·m (lb·in) |
|---|
| M10 black oxide bolts, mild steel nuts | 58 (515) | 40 (355) |
| 3/8 × 16 steel nuts and bolts | 32 (285) | 16 (140) |
| 3/8 × 16, pre-torqued to 5 N·m | 29 (255) | 29 (255) |
Chemical resistance — steel
| Environment | °C | 500 h | 1,000 h | 3,000 h | 5,000 h |
|---|
| Motor oil (5W40 synthetic) | 125 | 170% | 165% | 150% | 145% |
| Brake fluid | 23 | 130% | 140% | 135% | 125% |
| Unleaded petrol | 23 | 130% | 130% | 110% | 105% |
| Ethanol | 23 | 130% | 130% | 125% | 120% |
| B100 bio-diesel | 23 | 115% | 115% | 105% | 100% |
| Acetone | 23 | 100% | 100% | 100% | 100% |
| DEF (AdBlue®) | 23 | 95% | 95% | 90% | 100% |
| Water / glycol 50:50 | 87 | 85% | 80% | 80% | 80% |
Chemical resistance — stainless steel
| Environment | °C | 500 h | 1,000 h | 3,000 h | 5,000 h |
|---|
| Sodium hydroxide 20% | 23 | 115% | 105% | 95% | 90% |
| Phosphoric acid 10% | 23 | 75% | 60% | 40% | 35% |
Cured material
| Glass transition temperature (ISO 11359-2) | 100°C |
| Coefficient of thermal expansion, below Tg | 93 × 10⁻⁶ K⁻¹ |
| Coefficient of thermal expansion, above Tg | 184 × 10⁻⁶ K⁻¹ |
| Heat ageing data published at | 120°C, 150°C, 180°C and 200°C |
| Cold strength | Tested to −75°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.
- 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.
Loctite 648 or 638?
Both are high-strength, oil-tolerant grades that cure on stainless. The split is gap against heat. 638 is thick (2,500 mPa·s) and fills gaps to 0.25 mm — the grade for a worn housing. 648 is thin (500 mPa·s), stronger at 31 N/mm², holds a glass transition of 100°C against 76°C, and is the one Henkel names for shrink fits. Tight fit or hot assembly → 648. Worn or open fit → 638.
Always read the current technical and safety data before use —
ask us and we'll send it with your quotation.
