LEVO AG, based in Switzerland, was founded in 1974, developing innovative technologies to make life easier for people with physical disabilities. The stand-up wheelchair is certainly one of its most important developments

The LEVO Summit EL wheelchair features an innovative design that allows it to convert from a seated to an upright position, simulating standing, with the push of a button. Its backrest is foldable and, with a weight of only 21 kg, it is the lightest wheelchair of its kind on the market. Its featherweight characteristics are due in part to the use of adhesive bonding in its assembly.

Reliable bonding of multiple materials

When it comes to joining components made from all kinds of materials, bonding is the most suitable process. In the case of the LEVO wheelchair, the carbon and aluminum parts of the wheel axle, as well as steel and aluminum elements of the frame, must have an extra-reliable connection. Mechanical joining elements such as screws or rivets would not only damage the carbon fiber structure and weaken the component, but also involve more time-consuming procedures.

Whichever adhesive is used in this application would have to withstand a temperature of 180 °C, which occurs during powder coating, as well as crash testing. When selecting the appropriate adhesive, LEVO placed great importance on easy processing and simple handling during the manufacturing process. DELO, together with its partner Credimex AG from Alpnach, Switzerland, recommended the use of a two-component epoxy resin. With this adhesive, Credimex ran the following tests in its laboratory:

• Bonding and dispensing tests
• Tests aiming to determine the proper surface pretreatment
• Strength of the bonded components after storing them in the oven at 180 °C for 30 minutes
• Evaluations of the optimal design for the wheelchair’s bonding geometry

After these tests, a pressure test was successfully conducted to ensure the safe use of the technically sophisticated bonded connections.

It all depends on the right adhesive

The two-component DELO-DUOPOX adhesive used for LEVO’s wheelchairs cures at room temperature (approx. 23 °) after mixing. Thanks to the DELO-XPRESS dispensing gun, the manual dispensing process is fast and simple, just as the wheelchair manufacturer requested.

As a high-strength structural adhesive, DELO-DUOPOX is often used for joining rods of many types and, in the case of this lightweight wheelchair, is used for bonding the entire frame. The adhesive can serve as a constructive element since almost any layer thickness is possible, and its viscosity provides sufficient flow resistance to allow the components to be joined manually. This all ensures a smooth production process.