Adhesive bonding process – advantages, applications

Three essential steps are required to make an adhesive joint, including

(a) surface preparation,

Part surfaces are cleaned by chemical etching or mechanical abrasion. Grinding, sanding, steel brushing, sanding and abrasive blasting are some of the mechanical cleaning methods. Next, the prepared surfaces are tested for their affinity to being wetted with water. It's called the water break test. Smooth spreading of water is an indication that the surface is chemically clean, while accumulation of droplets indicates the possibility of oil film forming on the surface.

(b) applying the adhesive to the corresponding surfaces, and

Adhesives are applied to the surface of the part through hand brushing, spraying, roller casting, knife coating and dipping. They are also applied as a foil or tape type coating to the surface. The adhesive is applied as a thick layer to one surface of the part or as a thin layer to the surfaces of both parts.

(c) assembly of parts/parts and joint curing.

After applying the adhesive, the parts are assembled and held together using clamps, tools, welding points or other accessories. During the assembly process, sufficient care must be taken that the open time of the adhesive is not exceeded, the parts are assembled in the correct sequence, the bonding is carried out under specified environmental conditions, and the parts are held together until cured.

Healing the joint
Curing is the process during which an adhesive changes from a liquid to a solid state. The adhesive cures using pressure and heat or the addition of a suitable catalyst. The pressure must always be evenly distributed throughout the joint. Curing temperature, time, and pressure combinations for different adherends and adhesive combinations are given elsewhere.

Advantages and disadvantages of adhesive joints

Advantages of joints glued with adhesive

• Fast and cheap joining technique
• Fans are not affected by the heat
• Uniform voltage distribution
• Possibility of joining large structures
• Ability to join different materials
• Possibility of bringing together very thin fans
• Gas-tight and liquid-tight joints
• No crevice corrosion
• No contact corrosion
• Good damping properties
• High dynamic resistance

Disadvantages of adhesive joints

• Limited heat stability
• High-strength adhesives are often brittle
• Long-term use may alter properties
• Cleaning and surface preparation of adherents is necessary in many cases
• Specific clamping devices are often required to secure the joint
• Difficult disassembly of joined parts

Applications of Honeycomb Panel Structure with Adhesive Joints

Adhesive joint applications
1. Bonding metal to non-metals, especially plastics, is the main application of adhesive bonding.
2. Used as an alternative to riveting in aircraft structures.
3. Widely applicable in attaching reinforcements to aircraft skin and assembling honeycomb structures in aircraft,
4. Using extensively in manufacturing aircraft internal structures and providing a smooth surface for supersonic airplanes.
5. Useful in the automobile industry for attaching brake linings to shoes, automatic transmission tracks and reinforcements,
6. Find applications in the manufacture of railway cars, boats, refrigerators, storage tanks and microwave reflectors for radar and space communications.