The VHB tapes are viscoelastic in nature. The foam absorbs energy and relaxes stress which provides these tapes with their unique properties.
Viscoelastic means the tape has both solid-like and liquid-like characteristics.
- Solid-like: Elasticity, strength, form stability.
- Liquid-like: Flow depending on time, temperature, rate and amount of loading.
The foam absorbs and dissipates energy to increase the effective strength of the surface bond. Absorbing energy in the foam is what provides the high level of strength, as well as the excellent fatigue resistance and sound and vibration damping properties.
The foam relaxes stress through viscous flow, reducing the long term stress on the surface bond line. 3M™ VHB™ Tapes, because of their resilient stress relaxing nature, allow parts to move independently such as with thermal expansion/contraction, as compared with traditional fasteners that either fight or must compensate for the movement.
3M™ VHB™ Tapes bond most surfaces permanently, but if you have to separate the surfaces and remove residue, 3M also has the tools for a fast, effective job.
3M™ Smart Tool
Use by hand or in an air chisel to quickly separate such bonded assemblies as overlapped panels and stiffeners.
3M™ Stripe Off Wheel
Takes residue off faster and easier than solvents or adhesive cleaners. Resilient rounded edge follows contours and irregular surfaces and cleans without scratches or damage to acrylic enamel or urethane paint.
Special Feature products have special performance characteristics. Products are available for:
- Situations where high dynamic stresses are involved
- Applications to paints and plastics including plasticised vinyl
- Situations that require a transparent tape
- When the tape is applied between 0°C and 10°C
- Components that are bonded before powder coating or need to withstand higher temperatures
General Purpose products are ideal for many interior and exterior industrial applications. These tapes have softer cores and are especially suited for textured surfaces or where sealing is required.
- All VHB Tapes provide good adhesion to most metals, glass and high surface energy plastics.*
- For higher performance on paints and plastics** use 4941, 4991, 5925, 5952, 5962 or 4945. The liner side of 4618, 4622 and 4624 has good adhesion to paints and plastics.
- Use General Purpose VHB Tapes or 4941 or 4991 when the surface is textured to get a more complete bond or when sealing the joint is a critical requirement.
- On flexible vinyls use only plasticiser resistant 4941, 4945 or 4991 (Note: the liner side of 4618, 4622 and 4624 is also plasticiser resistant).
* High surface energy plastics include acrylic, ABS, polycarbonate, PVC, polyester, Polyamide, Polyimide, Phenolic, Noryl.
** Low surface energy plastics include PVA, EVA, polystyrene, acetal and some paints. They may require priming with 3M Tape Primer 94. Very low surface energy plastics such as polypropylene, polyethylene and EPDM are difficult surfaces to stick to. Primer 94 may improve the performance on these surfaces.
- The tape thickness required depends on the mismatch between the surfaces to be joined. The more closely the two surfaces fit together the thinner the tape can be. Generally, the tape can accommodate up to 50% of its thickness in a mismatch (i.e. the tape should be at least twice as thick as the mismatch). If in doubt, use a thicker tape to ensure a significant area of the tape forms a bond.
- When bonding sheets or large pieces, the thickness of the material should not be more than twice the tape thickness, e.g. 1.1mm thick tape is commonly used to bond sheets up to 2.2mm thick.
- Thermal expansion and contraction or movement in the joint should not exceed three times the tape thickness. Generally, a 2.4m length of plastic can be bonded to metal using a 1.1mm thick tape.
In shear (e.g. holding a sign or panel to a wall) the suggested amount of tape to hold up 1 kg is about 55cm^2 or for:
|Standard Tape Widths||Tape Length|
|12.7 mm wide||430 mm|
|19.0 mm wide||290 mm|
|25.4 mm wide||215 mm|
These amounts of tape include a significant factor of safety to allow for the different properties of the tapes in the VHB Tape range. These amounts can be reduced by up to 50% depending on the tape type if customer evaluation gives satisfactory results.
The desirable tape application temperature range is 20ºC - 40ºC. There are VHB Tapes with special properties that allow low temperature application.
The minimum suggested surface temperatures for tape application are:
16°C: 4936, 4941, 4945, 4991
10°C: 4611, 4618, 4622, 4624, 4905, 4910, 4915, 4918, 4930, 4950, 4959, 5925, 5952, 5962, 9473
0°C: 4951, 4957 (on high surface energy substrates only)
Once properly applied, low temperature holding is generally satisfactory down to -40°C