APPLICATION OF BONDING TECHNOLOGY IN THE BUS INDUSTRY

Bonding technology is a new technology in the bus industry. With the rapid development of China's economy, bonding technology has become more and more widely used in the bus field in recent years. Bonding technology is to firmly connect various metal and non-metal components to achieve high strength requirements; or to connect two components together for sealing purposes. It has the advantages of simple process equipment, convenient operation, wide applications, excellent sealing and anti-corrosion performance, high strength and weather resistance.

1. Application of Bonding Technology on Bus

1)Application of bus bonding technology

In the production of buses, the areas need to adopt the bonding technology include: front windshield, rear windshield, side window glass, connection between FRP and skeleton, fixing of lamps and interior parts, etc., these areas requires high-strength connections; Areas that need sealing technology include: hatch closures, door welds, glass caulks, floor seals, adhesive in metal and non-metallic joints, and pipe joints. The difference between the two technologies is that the type of the adhesive is different, the bonding type uses a high-strength adhesive, and the sealing type uses a relatively low-strength sealing adhesive.

2)Adhesive Selection

①Select the adhesive according to the chemical properties of the material. When bonding composite materials such as steel, aluminum, PVC, etc., high-strength adhesives such as epoxy resin adhesive, polyurethane adhesive, acryl ester adhesive, acrylate adhesive, inorganic adhesive, etc. should be selected: bonding  weakly polar or non-polar materials such as polyethylene, polypropylene, polystyrene, we should choose acrylate adhesive or solvent that can dissolve the material to be bonded such as chloroform, dichloromethane.

②Select the adhesive according to the physical properties of the selected material. Bonding cement, ceramic and other brittle or rigid materials, should choose high-strength, high-hardness, non-deformable thermosetting resin adhesive, such as epoxy resin adhesive, phenolic resin adhesive; bonding rubber, leather, plastic and other elastic or rigid materials, adhesives with good elasticity and certain toughness, such as neoprene or polyurethane adhesive, should be selected; when bonding porous materials, such as foam, sponge, fabric, etc., adhesives with higher viscosity, such as epoxy resin adhesive and polyurethane adhesive, polyvinyl acetate adhesive, rubber type adhesive should be selected.

③Select the adhesive according to the using condition. When the adhesive parts are subjected to the peeling force and the uneven pull-off force, a good toughness adhesive such as rubber adhesive or polyurethane adhesive may be selected: when subjected to the uniform pulling force and the shearing force, the hardening adhesive may be selected, such as epoxy resin adhesives, acrylate adhesives, etc.; when adhesive parts are required to have good water resistance, epoxy resin adhesives, polyurethane adhesives, etc can be chosen. Adhesives with good oil resistance are phenolic-butyl rubber adhesives, oxygen resin adhesives, etc.

④Select the adhesive according to the temperature of the used parts. Different adhesives have different using temperatures. For example, epoxy resin adhesives is suitable for use below 120 °C: rubber adhesive is suitable for use below 80 °C: organic silicon adhesive is suitable for use below 200 °C: inorganic adhesive is suitable for use below 500 °C or above 1000 °C.

3) Coating Adhesive Process

The correct coating adhesive process is the key to the product quality assurance. All types of coatings adhesive on buses have a detailed process, and operators are strictly required to work according to the coating adhesive process. The basic coating adhesive process is as follows: I. Treatment of the surface of the material to be coated. When using adhesives, the surface treatment requirements are strict, and the corresponding adhesives are provided with the corresponding cleaning agent and primer. II. According to the process requirements, some adhesives are added during the construction. III. Apply adhesive according to process requirements. IV. Colloidal solidification. V. Adhesive assembly. VI. Bonding quality inspection

2. Summary

The bonding technology applied to the domestic buses is late, and there is still a certain gap compared with the foreign technology. In the actual bus production, there are still many problems. The more prominent problem is that the quality is weak with not strong bonding and cracking aging. Sometimes the tear strength does not meet the theoretical requirements. However, these problems will be improved in future production practices.