How to choose an adhesive?
(1) Consider the type, size and hardness of the bonding material;
(2) Considering the shape structure and process conditions of the bonding material;
(3) Consider the load and form (tension, shear force, peeling force, etc.) of the bonded part;
(4) Consider the special requirements of materials such as electrical and thermal resistance, high temperature resistance and low temperature resistance.
Bonding material properties
(1) Metal: After the surface treatment of the oxide film on the metal surface, it is easy to bond; because the two-phase linear expansion coefficient of the adhesive bonding metal is too different, the adhesive layer is easy to generate internal stress; Produces electrochemical corrosion.
(2) Rubber: The greater the polarity of the rubber, the better the bonding effect. Among them, nitrile butadiene rubber has high polarity and strong bonding strength; natural rubber, silicone rubber and butyl rubber have low polarity and weak adhesion. In addition, the rubber surface often has a release agent or other free auxiliaries, which hinders the bonding effect.
(3) Wood: It is a porous material that is easy to absorb moisture, causing dimensional changes, which may result in stress concentration. In addition, the polished material has better bonding properties than the rough surface wood.
(4) Plastic: Plastics with high polarity have good bonding performance.
(5) Glass: The surface of the glass is composed of a number of uniform uneven portions from a microscopic angle. The use of a good wettability agent prevents the presence of bubbles in the unevenness. In addition, the glass is based on si-o- The surface layer is easy to adsorb water. Due to the strong polarity of the glass, the polar adhesive is easy to hydrogen bond with the surface to form a strong bond. The glass is brittle and transparent, and these should be considered when selecting the adhesive.
Features and choices
(1). Connecting materials of different elastic modulus and thickness, especially thin materials;
(2). The bonding surface is smooth and the aerodynamics are good;
(3). Good sealing performance and good corrosion performance;
(4). Extend the service life of the joint and reduce the weight of the joint;
(5). Low labor intensity, low cost and high production efficiency;
(6). Non-conductive rubber heat-resistant and seismic insulation, wherein:
a. The order of flexibility of the modified epoxy resin is: epoxy-polysulfide>; epoxy-polyamide>; epoxy-amine curing agent;
b. The order of flexibility of the modified phenolic is: phenolic-polyamide>; phenolic-polyvinyl acetate>; phenolic-epoxy;
In order to ensure the quality of the glue, the following must be done:
(1) Select the adhesive that is used.
(2) Both aspects of high adhesive strength and good durability are considered.
(3) Do not use adhesives that exceed the shelf life and pot life.
(4) If the single component glue is layered, precipitated, and stirred evenly before use.
(5) Multi-component glue should be mixed and mixed according to the specified ratio.
(6) Do not use simple docking.
(7) Try to use lap, miter, socket, and hybrid connections.
(8) The length of the overlap should not be too long.
(9) Adhesive laminates should not be lapped and mitered
(10) Adding screws and rivets, wrapping the edges and preventing peeling.