ADHESIVES, GLUES AND SEALANTS
The use of adhesives or glues as bonding materials has a number of advantages over other materials or techniques, but also it presents a number of drawbacks and disadvantages, in this section you will find the disadvantages and drawbacks of using adhesives or glues materials:
Time to cure - The final strength of the adhesive bond is not obtained immediately, unlike the case with a rivet or a screw, you must wait a time to solidify or cure the adhesive, this time depends on the choice of adhesive to be used, and also sometimes it depends on the environmental conditions that make the bonding process. If you want to reduce this waiting time you can use a chemical booster compatible with the adhesive.
Resistance to temperature - Adhesives are polymer-based materials, for this reason the adhesives and glues have an average resistance to temperature, adhesives silicone-based are more resistant to temperature adhesives, that kind of glues can withstand temperatures reaching point of 800 °C.
Ageing - The long-term strength of adhesive bonding is affected by various physical and chemical actions which are in the environment, actions such as ultraviolet light, chemical attacks on the environment, the presence of moisture . There are adhesives that are not altered against ultraviolet light while others break down in front of this radiation. The solution to this problem is to select an adhesive according to the environmental conditions in later work; this will allow us to perform a series of accelerated aging tests in order to observe the goodness of the adhesive bond.
Surface Preparation - As in the process of painting, surface preparation required prior to adhesive application process in order to achieve good adhesion between the adhesive and the substrate. Surface preparation that will vary depending on the materials to be bonded, the adhesive selected and technical requirements needed to fulfill the adhesive bond.
Removal or disassembly - As in the welding or rivet process, the process of disassembly adhesive bonds can destroy or distort the substrates joint together, being an expensive process to do, this does not happen when using techniques such as bolting, is so that those unions that require disassembly during maintenance work during the life of the product, must perform techniques that allow easy disassembly and assembly, such as using screws, velcro, etc...
Safety and Environment - Due the basis of the adhesives are chemical compounds, it is necessary to define the necessary actions to prevent human exposure to these products during the time of application, these measures will depend on the application amount and the type of the adhesive, glue or sealant used. Also you must properly manage the waste generated during the application process for further treatment and recycling.
Special process - Like with the technique of welding, adhesive technique is a special process, depending on the complexity and risk involved in the union made with adhesive, and the area or sector that uses it, it is necessary to have staff who deal with the design, monitoring, verification and application with the proper skills and capacity that can ensure the correct process of adhesive, such as an industrial level is currently being implemented there is the German rules DIN 6701 which specifies all the aspects taken into account in order to ensure the adhesive bond from its design until the maintenance of the joint.
The knowledge of each of the various joining techniques currently available (adhesives, welding, riveting, bolting, etc. ...), will allow us to select the optimal technique for each case in which we want to join 2 or more parts, due each of these techniques has advantages and disadvantages compare with the others.
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