TWI Industrial Member Report Summary 548/1996
S M Tavakoli
The strength of an adhesive joint may be adequate on the day you made it, but for it to last you need to have chosen the right adhesive, and the right pre-treatment.
Industrial use of adhesives is increasing - in some applications they have important advantages over mechanical fastening or welding. Adhesive joints can be designed to have lower stress concentrations, they are versatile and can be used to join materials which are dissimilar or heat sensitive.
The initial strength of an adhesive joint is an important benchmark - but joints are frequently exposed to a variety of hostile conditions in service - for example damp, solvents, loading cycles. This exposure can reduce joint strength significantly, and it is of vital importance to be aware of this in the selection of adhesives for critical or structural engineering applications.
It is therefore important to know which adhesives are best for the projected service conditions. Several different classes of adhesive are available, with differing physical and chemical properties - each have their strengths and weaknesses. The adherend is also an important factor, since there is always the danger that harmful agents may attack the interface between the adhesive and it. The preparation of the surface prior to making the joint can be crucial in preserving this interface.
For joints between adherends consisting of similar pairs of materials from the range aluminium, titanium, steel and polymers:
- To collect the information available on durability of adhesives and adhesive joints when exposed to all the most common service conditions.