Mitsubishi Materials Corp. said Thursday it has uncovered more instances of product data falsification at its subsidiaries in a protracted scandal that has tarnished the image of Japanese manufactures.
According to an internal probe by the corporation, its subsidiaries Mitsubishi Aluminum Co., Tachibana Metal Co. and Diamet Corp. were all found to have manipulated inspection data.
Mitsubishi Aluminum shipped products with falsified data to 115 companies, while Tachibana Metal Co. dispatched products with false data to 307 firms.
Diamet Corp., producer of industrial and automotive components, shipped potentially sub-standard products to 73 of its clients.
"I deeply apologize for causing great trouble to customers and people involved," Mitsubishi Materials President Akira Takeuchi was quoted as telling a press briefing on the matter.
Takeuchi said, however, he will not step down to account for the firm's improprieties.
Mitsubishi Materials has been under the spotlight for its subsidiaries' data falsification scandals, with internal probes beginning last year at Mitsubishi Cable Industries Ltd., Mitsubishi Shindoh Co. and Mitsubishi Aluminum.
The revelations led to Mitsubishi Cable Industry's President Hiroaki Murata stepping down to account for its involvement in the scandal, which saw the company knowingly continue to dispatch affected products after the scandal first came to light.
Mitsubishi Cable was initially found to have not conducted inspections on some of its sealing products, such as those used to joint pipes, and rigged data related to magnetic wires for use in electrical equipment.
The improprieties at Mitsubishi Cable first came to light in December 2016 following a quality control audit, according to its parent company.
Mitsubishi Materials said that it subsequently found that data had again been falsified in February 2017, with the firm carrying out further internal probes since.
Mitsubishi Shindoh Co., a copper production unit of Mitsubishi Materials, meanwhile, was also found to have falsified inspection data on products including brass strips used for components in the automotive industry.
Mitsubishi Shindoh Co.'s products with falsified inspection data were said to have sent to firms for an entire year beginning from October 2016.
Mitsubishi Materials Corp.'s ongoing quality control scandal has highlighted an endemic problem in Japanese industries, with similar scandals also involving other major manufacturers here including Kobe Steel Ltd.
Automakers including Nissan Motor Co. and Subaru Corp. have also been under fire for using uncertified staff to carry out final vehicle inspections.