16. Selection of Adhesives

Selection of the correct adhesive for an application can be a daunting task due to the many types commercially available ranging from different chemistries through different forms to an almost continuum of material properties. It is critical therefore to take a logical approach to this task and apply deselection criteria wherever possible. The needs of the final application are paramount and often a detailed review of the requirements can provide the engineer with some key selection needs or constraints which in turn may enable large groups of adhesives to be eliminated from consideration at an early stage of the process. In parallel to the needs of the final product, it is also important to appraise aspects related to manufacturing in terms of product volume, handling issues, curing equipment, dispensing equipment, etc., as an apparently perfect adhesive with the correct bond properties may not be able to be dispensed easily or it may require curing at temperatures above which the substrate cannot tolerate.

Although the initial adhesive selection process is essentially a desktop exercise, the need to be smart and identify a small number of candidates with the greatest potential requires that this activity be given a high level of importance. Almost every application will require a bespoke approach to some extent and this will necessitate practical testing and trials to be carried out. Selection of unsuitable adhesives at the outset could be costly in the long run.