Application of adhesives in equipment maintenance-Xiangyang Fengshen New Materials Co., Ltd

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Application of adhesives in equipment maintenance

Category：Industry information time： 2024-03-11 Author：Xiangyang Fengshen New material Co., LTD

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1 Selection of adhesives
Adhesives can be divided into organic and inorganic two categories. Organic adhesives include synthetic organic polymer adhesives and natural organic polymer adhesives. Synthetic organic polymer adhesives are widely used in daily equipment maintenance. Such as modified resin, anaerobic adhesive, silicone rubber, polyurethane, modified acrylates and so on.
When selecting adhesives in equipment maintenance, the nature of the adhesive, the nature of the material to be bonded, the shape, structure and process conditions, the form of load on the bonding part (tensile force, shear force, peeling force, etc.) and the cost and operating environment should be considered comprehensively, and the adhesive that meets the specific needs should be selected.
2 Bonding process
The bonding process mainly includes joint design, surface treatment, gluing and gluing, curing and quality inspection.
2.1 Joint Design
There are many forms of bonding joints in practical applications, but they can be simplified into three basic forms: end joint, Angle joint and surface joint. There are four typical stress forms of the joint, namely shear, tensile, uneven pulling and stripping. In the joint design, in order to improve the bearing capacity of the joint, the joint should be designed into a shear state as far as possible, the bonding area should be reasonably increased and the stress concentration should be avoided as far as possible.
2.2 Surface Treatment
In order to obtain a adhesive joint with high bonding strength and good durability, it is required that the prepared surface layer must be firmly combined with the base material and the adhesive, and this combination is not or less affected by environmental conditions. The main functions of surface treatment are: removing the surface dirt and loose layer that hinder bonding; Improve surface energy; Increase the surface area. The quality of surface treatment directly affects the bonding strength of bonding materials. The main influencing factors are cleanliness, roughness and surface chemical structure.
2.2.1 Cleanliness
To obtain good bonding strength, the necessary condition is that the adhesive infiltrates the surface of the bonding material. Generally, pure metal surfaces have high surface free energy, while organic adhesives are mostly polymer compounds with low surface free energy. According to the principle of thermodynamics, they can be well infiltrated between them, but in fact the obtained metal is not a pure metal surface, its surface often has a layer of rust or oxide, and organic or inorganic pollutants adsorbed in the process of metal manufacturing, cutting, molding processing, heat treatment and so on. The cohesion strength of the pollution layer composed of these pollutants is very low, and their presence generally reduces the bonding strength.
2.2.2 Roughness
Proper roughening of the surface can improve the bonding strength. But the roughness can not exceed a certain limit, the surface is too rough will reduce the bonding strength. Because the surface that is too rough can not be well infiltrated by the adhesive, the residual air in the concave space is not conducive to bonding. The bonding strength is also closely related to the different surface geometries produced by roughening methods. For example, the bonding strength of sandblasting is higher than that of polishing and then machined roughening; Sharp abrasives have higher bonding strength than those treated with spherical abrasives. The process of mechanical roughening can purify the surface, change the physical and chemical state of the surface, and form a new surface layer. At the same time, the difference of roughness will also affect the stress distribution on the interface, so as to obtain better bonding strength.
2.2.3 Surface chemical structure
The chemical composition and structure of the surface of the bonding material have important effects on the bonding properties, durability and thermal aging properties. The influence of surface structure on bonding properties is often achieved by changing the cohesive strength, thickness, porosity, activity and surface free energy of the surface layer. Among them, the surface chemical structure can not only cause the change of physical and chemical properties of the surface, but also cause the change of cohesive strength of the surface layer, so it has a significant impact on the adhesion property
2.3 Gluing
For single-component adhesives do not need to be prepared, can be used directly. For two-component or multi-component adhesives, the quality of the adhesive will directly affect the bonding performance of the adhesive, and the weight of each component must be accurately weighed (the error is generally not more than 2% to 5%) and stirred evenly. The amount of adhesive preparation should be determined according to the amount of coating and used up during the active period.
2.3 Bonding
After the surface treatment of the bonded part is completed and the adhesive is finished, the adhesive can be applied according to the specified requirements. Field maintenance is generally carried out by brush, scraper, roller or glue machine. The adhesive coating should be uniform and free of bubbles, and the thickness of the adhesive film should be controlled within the specified range. After the adhesive is coated, the adhesive shall be cured according to the curing method, time and temperature specified in the adhesive instructions, and compressive stress shall be applied to the adhesive during the curing period.

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Application of adhesives in equipment maintenance