Method for discriminating good or bad of product

Method for discriminating good or bad of product

Keywords: Assembly, Patents

Applicant: Sumitomo heavy industries

Patent number: JP2003181874

Publication date: 2 July 2003

Problem to be solved: To accurately discriminate good or bad of a product by dynamically changing an item used to discriminate at each manufacturing time by using an Maharanobis Taguchi system (MTS) method to deal with a change of a phenomenon. Solution: In the case of an injection molding machine, at step S5,distances of Maharanobis of n ways are calculated by using a plurality of items of result values of M of each shot are calculated according to a combination of an orthogonal table. At step S6, SN ratios of the n ways are calculated from the distances of the Maharanobis. At step S7, a level means(first level, second level of the table) of the items is calculated by using the calculated SN ratios, and m items are observed from larger one of the level mean difference (first level mean – second level mean). Again, mpieces of the distance of the Maharanobis are calculated by using these optimum m items, and if any one of the m pieces of the distances exceeds the reference value, it is decided to be a fault.