Electricity disbonds adhesives
Do you bolt it, glue it or weld it? This is a question that can be asked a number of times in any design process across a great many industries
May 2002 its so simple: Electricity disbonds adhesives
Problem: .
The answer is, of course, dependent on the application, as each of the processes offers its own advantages although, hand in hand with these are the disadvantages.
Bolting is tough, reversible but time-consuming; gluing is easy to do but difficult to reverse depending on the adhesive used; and welding is as permanent as it gets and very difficult to 'undo'.
Designers often have to trade these factors off against each other to arrive at the best possible joint for their design.
Adhesives certainly offer the more attractive option in many cases but, should disbonding be required, they can present all sorts of process problems - especially when high strength joints are needed
Solution: A high strength adhesive has been developed which can be separated or disbonded by the application of a low DC voltage.
Called ElectRelease, the two-part, room-temperature curing epoxy can bond most metals used in scientific or industrial applications.
Offering a lap shear strength of 2,500psi it is suitable for aluminium alloys, stainless steel and copper.
Available in the UK from Electromotif, this new adhesive's disbonding capability stems from electrochemical reactions occurring at the interface between the epoxy and metal when the voltage is applied. Typical voltages at 10 to 50Vdc result in a current flow of less than 1mA/in2.
Application: The technology was originally developed under a program supported by the US Air Force. It sought a means of bonding test packages to the exterior of jet aircraft without using mechanical fasteners.
The packages only weighed a few pounds and had to withstand speeds of up to MACH II before being successfully removed without damage to themselves or the aircraft being tested.
The adhesive, which is also suitable for long-term applications, can replace mechanical fasteners, welds and other adhesives in temporary bonding applications and is being actively marketed to the automotive, aerospace and shipbuliding industries. Specialised applications for payload release systems for land, sea and air vehicles are also expected. MF
