What factors influence the selection of adhesive types?

1. Familiarize yourself with adhesive properties

Adhesives are fundamental to the bonding process, and their properties serve as a crucial basis for selection. Different types of adhesives possess distinct properties that determine their specific applications; only by understanding these properties can one select the right adhesive effectively.

2. Understand the characteristics of the substrates

There is a wide variety of substrates with vastly different characteristics, and the properties of materials within each category also vary; therefore, the appropriate adhesive must be chosen based on the specific characteristics of the material. Materials are classified into metals, non-metals, and composite materials.

3. Factors Related to Service Conditions Must Not Be Overlooked

Bonded assemblies are invariably used under specific conditions, and these conditions significantly influence bonding performance; therefore, service conditions must be taken into account when selecting an adhesive.

1) Temperature

Different adhesives exhibit varying degrees of heat resistance. Some offer high heat resistance and can be used at elevated temperatures, while others have poor heat resistance and are suitable only for lower temperatures. Most adhesives perform well at low temperatures, and some can even be used in cryogenic environments. The typical operating temperature range for adhesives is -40°C to 150°C.

2) Humidity

Moisture and water are detrimental to the stability of the bonded interface; they are strictly harmful. In high-humidity environments, adhesives such as cyanoacrylate (502 glue), unsaturated polyester resin, and epoxy-polyamide should be avoided; instead, options like phenolic-nitrile, epoxy-nitrile, or epoxy-polysulfide adhesives should be selected. High-temperature curing is preferable.

3) Chemical Media

Chemical media primarily include acids, alkalis, salts, and solvents. Different types of adhesives and curing conditions offer varying levels of resistance to these media; therefore, the adhesive should be selected based on the specific media to which the bonded assembly will be exposed.

4. Consideration of Process Feasibility

Different adhesives require different processing conditions: some cure fully at room temperature, while others require heat; some cure rapidly, while others cure slowly. On continuous production lines where long curing times are not feasible, fast-curing adhesives must be selected.