Safran Aircraft Engines

Nicolas Hardouin

Pascal Courtin

Olivier Ferry

Arnaud Cambefort

Charles Cleret De Langavant

The invention pertains to a method of manufacturing a population of parts produced with a manufacturing device, based on the analysis of at least one statistical indicator representative of a characteristic dimension of the parts, according to which: a) a sample comprising a number n of parts is collected from among the parts produced with the manufacturing device; b) the characteristic dimension of each part of the sample is measured, and a measured value of the statistical indicator is calculated for the sample; c) a mathematical expectation of the proportion of parts which are noncompliant with respect to a specification regarding the characteristic dimension is calculated, said calculation being performed on the basis of the measured value of the statistical indicator for the sample collected and of the number n of parts of the sample; d) the mathematical expectation of the proportion of parts that are noncompliant calculated is compared with a threshold value of proportion of noncompliant parts; e) the manufacture of the parts is steered as a function of the results of the comparison of step d).

Method of manufacturing parts based on analysis of statistical indicators in a situation of diminished control

The invention pertains to a method of manufacturing parts produced with a manufacturing device, based on the analysis of at least one statistical indicator representative of a characteristic dimension of the parts, according to which: a) in the course of time several samples are collected, each sample comprising several parts produced with the manufacturing device; b) the characteristic dimension of each part of the sample is measured; c) for each sample collected a weighted mean and a weighted standard deviation of the characteristic dimension are calculated according to an exponential weighting on the basis of a mean and standard deviation of the characteristic dimensions measured on the parts of said sample, of weighted means and of weighted standard deviations of the characteristic dimension which are calculated for previously collected samples; d) for each sample collected a value of the statistical indicator is calculated on the basis of the weighted mean and of the weighted standard deviation thus calculated; e) a value of the statistical indicator thus calculated for the sample collected is compared with a reference value to detect a possible deviation; f) the manufacture of the parts is steered as a function of the results of the comparison by fitting the manufacturing device adjustment parameters to optimize the deviation between the value of the statistical indicator and the reference value.

Method for manufacturing parts based on analysis of weighted statistical indicators

The invention pertains to a method of manufacturing parts, where each part must satisfy a global dimensional requirement on a specific dimension of said part akin to a tolerance stack up comprising at least two tolerances, each tolerance corresponding to a characteristic dimension of the part, where: the global dimensional requirement is fixed so that the specific dimension of the parts has a mean &#x3bc;and a standard deviation oG lying in a global acceptance range constructed on the basis of one or more statistical criteria; a reference dimension is chosen from among the characteristic dimensions, and a mean &#x3bc;&#x393;&#x3b2; and a standard deviation oref of said reference dimension are calculated on the basis of a sample of collected parts; a range of acceptance for the other characteristic dimensions of the tolerance stack up constructed with the same statistical criterion or criteria as the global acceptance range is calculated on the basis of the global acceptance range and on the basis of the mean ITO and the standard deviation oref calculated for the reference dimension; the manufacture of parts is steered without verification of the reference dimension by using the acceptance range calculated for the other characteristic dimensions of the tolerance stack up by fitting the adjustment parameters of a manufacturing device so that each of the other characteristic dimensions of the tolerance stack up lie in the corresponding calculated acceptance range.

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Moissy-Cramayel, France

Nicolas Hardouin