Wuhan Yaohua Safety Glass striving to become world leader by using patented optical quality control system

Windshields of bent glass may generate undesirable optical distortion effects resulting in impaired viewing. For car buyers, however, they are an important aesthetic property. Automobile manufacturers therefore impose stringent conditions on their suppliers: Windshields have to meet precisely specified optical requirements and be perfect in quality.

The Chinese producer Wuhan Yaohua Safety Glass Co., Ltd. guarantees this quality level by applying innovative ISRA VISION inspection technology. With SCREENSCAN-FAULTFINDER, the company has integrated a system for fully automated continuous in-line inspection of produced windshields into their manufacturing process. It measures the transmission optics of each glass and evaluates optical distortion which may be a result of the bending process. The integrated analysis tools are used to identify typical defect sources, which have allowed for achieving perfect delivery quality and significantly increased the efficiency of the Wuhan production facility.

With headquarters in the province capital of Wuhan and located in the center of the Economic and Technological Development Zone, Wuhan Yaohua Safety Glass Co., Ltd. has been a key producer of safety and automobile glass for 20 years. The company is a member of NSG-Pilkington Group and one of the top five producers of automobile glass worldwide. The list of customers includes reputable manufacturers such as Renault, Peugeot, Citroen, Nissan and Honda.

Customer requirements regarding improved product quality lead Wuhan Yaohua Safety Glass to replace manual final inspection of their windshields by an automated optical inspection solution. "On the long term, man is not capable of continually detecting and evaluating partially tiny defects on the transparent or coated glass surfaces with reliability. We selected ISRA as our technology partner, since their systems have an excellent reputation in the industry", states Zheng Wen, Technical Director of the Wuhan production facility, as the reason for the global player's decision.

SCREENSCAN-FAULTFINDER with Online-Moiré-Technology for reliable and reproducible gauging with high resolution

The picture shows the system as installed on production line 1 of Wuhan Yaohua Safety Glass.

Patented Online-Moiré-Technology identifies defects

As a result of the production process, windshields of laminated glass vary in their optical characteristics. In order to verify their marketability, the screens of Wuhan Yaohua's production line 1 pass a final inspection by SCREENSCAN-FAULTFINDER after two manual inspections. The ISRA system operates on a 1.25m-wide line which runs at a speed of 12m/min.

SCREENSCAN-FAULTFINDER inspects the horizontal and vertical transmission optics of the screen by using the Online-Moiré-Technology developed and patented by ISRA. In this procedure, the system measures the aberration of light in the bent glass at a typical inspection angle of 30°. Distorted areas and absorb ing defects such as laminated hairs or edge defects are identified 100% and displayed by the software. The sensor technology is not sensitive to dust particles and finger prints.

Equipped with up-to-date optical inspection technology, Wuhan Yaohua Safety Glass is capable of translating the optical quality of screens produced into countable figures. "The application of SCREENSCAN-FAULTFINDER is a relief for us", says Zheng Wen.

"We finally have precise, objective inspection results which are quantifiable and reproducible. In addition, we save an entire process stage, since we always performed the manual final inspection procedure twice."

Wuhan Yaohua Safety Glass uses the system for the inspection of windshields; it is generally also compatible for back and side lites.

The picture shows SCREENSCAN-Faultfinder in the facility in Wuhan, China.

Detailed defect recording reveals saving potentials

Wuhan Yaohua Safety Glass now handles the final quality inspection of their windshields rapidly and exactly in-line while benefiting from increased yield at the same time. The integrated, user-friendly analysis tools record measuring results and indicate the processes where defects occur. Based on this information, which is crucial for quality management, the Chinese producer could optimize production processes and increase the overall production efficiency. Zheng Wen adds: "Since we have introduced an optical inspection system, we have considerably saved resources and increased quality. This also drastically reduced the number of customer complaints."

Efficient quality management which only became possible due to detailed evaluation logs has become the flagship of Wuhan Yaohua Safety Glass and is used by the company for advertising and acquiring new customers from all over the world.

Conclusion

SCREENSCAN-FAULTFINDER has improved the overall facility's productivity, increased quality and reduced resource usage. The changeover to fully automated, continuous in-line inspection of windshields has consequently been an essential step for Wuhan Yaohua Safety Glass towards strengthening their market position. "We have started a trend for the future of our facility", concludes Zheng Wen. The investment in the ISRA inspection system has quickly paid off for Wuhan Yaohua Safety Glass.