The use of solvent welding for component assembly has become both a mechanical and environmental issue. As environmental regulations and operator safety become issues for manufacturers throughout the world, the use of solvents in a production environment have become more problematic. Ozone-depleting chemicals have often been replaced by flammable, more harmful alternatives that are now causing designers to seek other options. In addition, solvent welding cannot be used effectively on thermoset plastics and is more likely to cause stress cracking of components versus other liquid joining methods (i.e. adhesives). Solvent bonding/welding is also not capable of securing joints with large induced gaps. Application amount and time are also critical factors that must be closely monitored when using solvent bonding to ensure consistency of performance.
To address the limitations of solvent-based assembly methods, manufacturers have responded by adopting solvent-free adhesive systems as a primary means of assembly. Solvent-free adhesive technologies provide many advantages beyond regulatory compliance and operator safety concerns. Some advantages of solvent-free adhesives include:
- They can be used with dissimilar materials such as metal and glass.
- Adhesives effectively bond thermoset plastics and rubbers.
- They are less likely to cause stress cracking in parts.
- Adhesives have a much less critical open time; by contrast, the time between application of the solvent and joining the parts is critical, and joints become weak if too much solvent remains in the bond area or if too much solvent has flashed off prior to assembly.
- Adhesives tolerate much larger gaps in the assembly joint.
- They distribute stress loads across the entire joint.
- Adhesives both bond and seal.
- Dispensing of adhesives can be easily automated.
- Where aesthetics are a factor, adhesives provide an aesthetically acceptable assembly.
