The basic function of an adhesive is to coat the surfaces of adherends and connect them. When manufacturing bonded components, the first consideration is to select appropriate adhesives from various types. Here are eleven factors that influence the choice of adhesives:
1. Bonded Assembly

The entire processing of the bonded assembly has more or less influence on the selection of adhesives. The surface condition of the adherends created before bonding directly relates to the bonding effect. If it cannot be changed, then an adhesive that matches this surface should be selected. After bonding, the entire processing method (cutting, punching, heating, freezing, dipping, etc.) of the bonded component should also be considered when selecting the adhesive. If the entire bonded component is a unit in a production line, to synchronize with other units, the operating performance of the adhesive must be compatible with the speed of the production line. At the same time, the form of the adhesive (liquid, paste, film, or solid) should match the processing means of the bonded component (manual or mechanical).
2. Properties of the Adherends

The physical and chemical properties of the adherends and the degree of surface preparation required before bonding are another important factor to consider when selecting adhesives. The goal here is to expand the adhesion on the joint, so that the joint fails in cohesion during testing rather than at the adhesive/adherend interface. This is the only way to potentially achieve the highest strength of the adhesive.
3. Strength of the Adherends

Low-strength materials, such as fabrics, felts, or some materials similar to wood, may be weaker than the adhesive, so joint failure occurs within the material. For such applications, the selected adhesive should allow the bonded component to be used under any physical conditions that the material can endure, without the risk of adhesive failure. Using high-strength adhesives in this case would over-specify or overprice the bonded material.
4.Thickness of the Adherends 

The thickness of the adherends is another factor that cannot be ignored. Solvent-based adhesives tend to cause wrinkles at the edges of the joints when bonding thermoplastic films or their composites, while they often reduce the requirements for surface treatment of rigid thermoplastic materials. The specific shape of the adherends usually facilitates the application of specific forms of adhesives. Aluminum honeycomb structures for edge joining flat metal sheets are best bonded using liquid primers and thermosetting adhesive films (lined with glass fiber cloth). Paste adhesives are convenient for making heat exchangers from copper fins and aluminum tubes. For porous materials, using adhesives with particularly high viscosity or paste-like adhesives is more suitable.