ADHESIVE BONDING
Description
| Adhesive bonding is a widely used joining process in the fabrication of engineering products. It forms an essential part of the laminating process in multimaterial sandwich structures andit is also used for structural connections between multimaterial components. Adhesive bonding is achieved by placing a 'liquid' or semi-liquid material between the components to wet the joint surfaces. Solidification of the liquid, usually by chemical reaction, then provides the joint strength. |
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| Schematic represesentation of adhesive bonding |
Contacts
composites-proc-assoc.co.uk/compbond.pdf
ciba-araldite.com/newco/addexn.html
Characteristics
| Costs (tooling / unit) | Manual techniques - low cost, can be self jigging or use simple
clamps.
High volume equipment with automatic dispensing and parts handling may cost from 1000 - 50,000Euro Pretreatment stages may be necessary |
| Volume (units / day) | Simple manual methods - 10 - 1000 per day
Mechanised/automated systems - 1000 - 100000 per day |
| Possible Materials | Most metals, polymers and composites can be joined by adhesive bonding. However special surface treatments may be required for some thermoplastics |
| Size / Shape | No real size limitations
Components should be designed so that the joint has a good bond area with minimum peel loading. Large flat surfaces, coaxial joints and containment joints are preferred. |
| Mechanical Properties | Depending on adhesive type and configuration, joints may be stronger than parent material. Shear strengths of up to 25 MPa are possible but typical design limits are 5MPa |
| Special Remarks | Adhesive bonding is a very versatile joining process and is particularly suitable for multimaterial products. However some care is necessary in joint design to minimise stress concentrations. For example in composite to metal joints tapered edges and fillets are recommended to reduce normal stresses which might otherwise lead to
delamination
The adhesive curing rate may require extended process times As NDT is difficult to apply to bonded joints, good process quality assurance methods should be used at every part of the bonding operation. |
Application / Case Study
Adhesive bonding is used in assembly from the smallest micrelectronic products to very large civil engineering and off-shore structures. An example of its application to multimaterial structures is illustrated in the high speed catamaran
The very lage composite front structure (7mx8mx1m and weighing 7tonnes) is attached to the aluminium deck by a combination of adhesive bonding and bolting