Mitsubishi automobile opened the factory to the news media while releasing the new factory. The reduction of manufacturing cost is achieved by three means: 1. Reduce the number of painting robots in the intermediate paint and topcoat process; 2. Introduce a new spray gun to reduce paint waste; 3. In the primer impregnation process, “Global For the first time ( Mitsubishi automobile) introduced a body handler to shorten the production line. 

        1 In terms of the reduction in the number of robots, the number of 18 robots in the previous intermediate paint and topcoat process was reduced to 14. By using a robot made by Yaskawa Electric, which is about 40% lighter than the original model, the machine that was previously installed on the floor is installed at a higher position on the wall, which expands the spray range of each robot.

       When spraying the upper part of the vehicle body, it is necessary to use one of the left and right sides of the conveyor line when using the original floor-standing robot. When installed at a higher position on the wall, only one unit can be used to spray almost the entire surface of the upper part of the body. Since the number of robots is reduced and the installation area is reduced, the length of the intermediate paint and topcoat line can be shortened from 153m to 146m, which also contributes to cost reduction.

       2 The new type of spray gun that sprays paint onto the body uses a tubular product made by ABB, Switzerland. In use, only the necessary amount of paint is placed in the cylinder, thereby reducing the wasted amount of the high-priced paint by about 60%. Originally, the paint was transported to the spray gun through the pipeline from the paint mixing place, and the residual paint in the pipe was washed away when the paint type was changed.

        (3) The vehicle body transporter in the primer step introduces an impregnation step of immersing the vehicle body in a large tank filled with an aqueous epoxy solvent for electrodeposition to improve the rust preventive performance. The characteristics of the transporter are that the angle of the front and rear direction of the vehicle body can be greatly changed. Use the L-shaped support to lift the front and rear of the body and change the angle of the body by moving the front and rear supports up and down. Originally, two hanger-like supports were used to lift the body, but the fulcrums of the support were respectively connected with the chain for the purpose of carrying, and the angle of the body could not be changed independently of the inclination of the track.

       By changing the angle of the body and increasing the angle of the groove and the groove, the length of the line can be shortened. The production line is about 30m, which is about 30% shorter than the original. In addition, it is also possible to finely adjust the angle in the groove according to the shape of the vehicle body, and remove the air trapped in the groove, thereby improving the adhesion of the solvent. In addition, by increasing the angle of the groove, the solvent can be easily "sag resistant". The time from the body to the slot is about 3 minutes. The carrier was jointly developed by TAIKISHA and DAIFUKU. The epoxy solvent was produced by Nippon Paint and a voltage of about 300 V was applied to the bath.

       In order to reduce energy consumption, the factory was changed to a three-layer structure, thereby reducing the energy required for cooling. Specifically, the process of using heat such as drying and baking paint is set on the third floor of the factory, and the process of operating a large energy-consuming device such as a robot is set on the second floor, and the manually operated process is set on the first floor. Since the heat will naturally rise, the process of generating heat is placed on the upper floor of the factory, which can lower the temperature of the first floor where the workers are located and reduce the use of cold air. Takahashi Masaki, Minister of Production Technology of Mitsubishi Motors Manufacturing Technology Co., Ltd. confidently said: "Although the idea is simple, the spray plant that is thoroughly used is unique."

     Intermediate paint and topcoat changed to waterborne paint

       The reduction in VOC is achieved by changing the solvent coating in the intermediate paint and topcoat process to a waterborne coating. To this end, we have adopted the “Three Wet Process” which has accumulated rich experience in the Mitsubishi Motors Water Island Plant. It was originally sprayed with a solvent coating in the intermediate paint process and then dried in a drying oven at 140 °C. In the topcoating process, the solvent coating is applied once, and then the solvent coating is applied to the surface, and the oven is grilled in a drying oven. This time, the paint used in the intermediate paint process and the paint used for the first time in the topcoat process were changed from solvent paint to water-based paint. In order to use the water-based paint, a process of spraying hot water of about 80 ° C after spraying the water-based paint to evaporate water is added. Thus, the drying furnace after the intermediate lacquering process is omitted, and in order to remove harmful substances such as formaldehyde, a regenerative deodorizing device is newly introduced into the drying furnace. This apparatus can heat the exhaust gas of the drying furnace to a high temperature of about 850 ° C, and oxidize and decompose the formaldehyde and the like contained therein.

       The new construction of the spray plant began around 2007, which has been in operation for 34 years since its completion in 1977, and its old age is serious. Moreover, after the Japanese Air Pollution Prevention Act was promulgated in 2006, it is also necessary to meet the requirements of this regulation.