Advantages & Limitations of Adhesive Bonding
The explanation so far might be concluded by listing major advantages of adhesive joints.
1. The adhesive joints help maintain the appearance of surfaces. This method needs no drilling of holes (as for riveted and bolted joints or screws).
2. Therefore, the original strength is not influenced and no stress concentration is introduced. The adhesive joint distributes the load uniformly on interface.
3. This has been earlier pointed out that there are two kinds of adhesives, viz., structural and non-structural. Primarily the former is meant for providing strength while latter serves such purposes as sealing, insulating, preventing corrosion among dissimilar metals, noise and dampening vibration.
4. The adhesives contribute little to weight when utilized to join thin parts.
5. Fragile components might be conveniently bonded as no machining is needed.
6. The materials to be jointed might be porous and might have very distinctly different properties.
7. Heat sensitive materials might be bonded since use of adhesives never requires temperature exceeding 200oC.
However, it is necessary to keep the limitations of these joints in mind before making decision to have them. These limitations have already been denoted at various points in above text.
1. Temperature & strength are two main weaknesses of adhesives. These joints cannot stand higher temperatures (in excess of 120oC) as encountered in various service situations. Their strengths are also restricted and most metals joined by adhesives may not be stressed to their capacity.
2. The bonding time is long and bonding needs elaborate tooling etc.
3. The surface preparation for making smooth, dust and grease free is quite tedious and expensive.
4. This is difficult to test a joint non-destructively, specifically if the structure is large.
5. The reliability of the joint remains low in service.