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Automotive outer panels may be distorted during heat treatments for curing of structural adhesives and mastic sealers. Distortion occurs due to residual stress between the adhesive and the panel following the curing process of the adhesive. The research discussed in this paper therefore considered a simulation technique of distortion and measuring method using curvature as the evaluative indicator. Curvature refers to the change of gradient of the curved surface, and the difference in curvature between the standard shape of the panel and the distortion section closely resembles the results of visual evaluations. Test panels were manufactured and measurements of their curvature were conducted. A study of the correlation of measurement results with the results of visual evaluations showed a good match.

A lightweight body sealer that cures at low temperatures was developed. In order to make the sealer lightweight, it is necessary to add light raw materials. In this development, the technique in which the weight reduction effect adds the resin balloon which is high and is easy to fluctuate the thickness and the particle diameter of shell was selected. Two types of resin balloons were used in combination with each other. High pressure-resistant resin balloons made of polyacrylonitrile (PAN) were one type, of which pressure resistance was increased by optimally designing heat-expandable microspheres (raw material), and the other type was high pressure-resistant polyester (PES) balloons. To enable the sealer to cure at low temperatures, it is necessary to use a resin that cures in the specified temperature zone and has the necessary physical properties.

The necessity of a high-precision disc to reduce brake judder was reconfirmed from the three viewpoints: a literature review, experiments, and bench marking. Geometric accuracy is the critical issue that brake disc suppliers must address to improve the NVH performance of automobiles. We have achieved disc lateral runout of less than 20 micrometers after rough and semi-finish turning operations by increasing the rigidity of lathe components and tool holders, improving work-holding devices, selecting appropriate cutting insert material and geometries, and optimizing cutting conditions. With an additional grinding process, by selecting the most suitable abrasive wheels, optimizing grinding conditions, and keeping the alignment of the work-piece and grinding-wheel spindles accurate through productive maintenance based on the in-line measurement data, we can correct the geometric dimensions of the disc friction plates to obtain higher accuracy.

Generally, ‘direct glazing’ is the bonding method used to install the automobile front and rear window glass. This bonding method is used for not only the safety of holding the glass in place but also for the marketability of appearance and precision, i.e. its fitting quality. In order to rationalize this bonding work process, sealant materials were developed with the function of temporarily supporting the glass, molding design specifications were developed with the function of spacer, and high-precision glass adhesion robots were developed (by Honda Engineering Co., Ltd.) in order to further raise the fitting quality. All this development made it possible to eliminate auxiiary fitting parts and to completely automate the glass bonding work process. As a result, the marketability of the vehicle is improved and the work process simplified to reduce costs.