Technology Reflecting Real-World Experience
Suzuka Factory introduced its high-efficiency coating line system to mass production in May 1988, dramatically reducing the number of steps needed to complete a car body. In particular, the coating process for the outer panels, which formerly employed a combination of skilled operators and machines, underwent a significant streamlining.
Installed on the line at the intermediate coating and overcoat application stages were several outer-panel-top multicoat robots, which were used to apply coatings over horizontal surfaces, along with outer-panel multicoat robots for vertical surfaces. Of the two, the former solved longstanding problems in the conventional reciprocator by adopting a configuration featuring several sprayguns. This permitted the robot to coat sections at the front and rear of the body that earlier machines had failed to reach. Moreover, the added function of moving the gun arm up and down according to body orientation made it possible for the coating material to be sprayed onto the body surface at a constant right angle. To enhance coating efficiency on the side surfaces of the body, gun arms were installed on the right and left sides of the line. Thus, the new system allowed the distances between these guns to be changed according to the target model, achieving an optimal coating effect. With that, the outer-panel coating line became fully automated, removing the need for operators to work manually.
The multirobots then employed in the inner-panel coating process were equipped with slim arms offering smooth movement and the ability to perform precise, high-speed coating in tight spaces around the body. One of the more significant factors in the achievement of an effective new coating system was the development and installation of dedicated opener/closer robots designed to open and close the hood, trunk, and doors during the coating process.
"In the process of coating the inner panel we had always used door jigs to keep the door in a closed or opened position while the coating was being applied," said Arai. "The robot technology we introduced to the process was developed by combining the wisdom of people experienced on the line, including the use of coating jigs. I believe the total effect of all these efforts was a greater degree of support for Honda's production technology."
The new, high-efficiency coating line employed a number of cutting-edge technologies. By developing its own coating facilities and machines, Honda achieved a significant savings in labor across the entire line. The new system consolidated operations that used to require two lines, yet it still met the production requirement of 1,100 units per day. Furthermore, the overall length of the coating line was reduced by approximately 36 percent. And, because of the reduced line length the time needed to move a workpiece through the coating process was reduced to around 33 percent of what it had been, meaning less liquid inventory. These achievements led to a dramatic reduction in the amount of energy needed to operate the line.
The high-density, integrated body-painting system introduced to Suzuka Factory's third line received the Ohkouchi Memorial Award for Production in 1991.