Determination of an adjusting rule in the case of multi-criteria inertial piloting

The weighted inertial piloting of processes presented in this paper is a break-away in terms of the quality of machined mechanical workpieces compared to the traditional piloting carried out by machine setters. However, sometimes one has a stability problem during the piloting phase due to over adjustment. We propose to study the causes of this instability and to develop an approach in order to correct the problems. Once we have reminded ourselves of the basics of weighted inertial tolerancing, we will propose an approach to identify the most probable decentring. The applications of the concepts discussed in this article were tested over a period of two months. The results are very convincing, especially with the elimination of the phenomenon previously observed in identical conditions

Correction of machining operations with the Total Inertial Steering

The Total Inertial Steering approach proposed in this paper can perform an optimum correction of the geometric deviations of the manufactured part with respect to its digital model, from the measured points on its surfaces. In the case of production by machine tool numerical control, there exist a link between the tool offsets and deviations of measured points. An incidence matrix which represents this link is obtained. In most cases, this matrix is not square and therefore not invertible, because there are more measured points as correctors to adjust. The Gauss pseudo-inverse is used to calculate the values of corrections to be made to compensate for measured deviations. Tolerances associated with the surfaces must also be taken into account in the incidence matrix. However, when the same cutting tool machine two surfaces with different point values, the resulting solution favors the one with the highest number of points, at the expense of the other surface which can remain not conform towards its tolerance. This paper proposes a strategy to rebalance the correction surfaces, and this regardless of the number of points and tolerance of each surfaces. A relatively simple tutorial example is given in the paper to enable tracking calculations

Correction of machining operations with the Total Inertial Steering

The Total Inertial Steering approach proposed in this paper can perform an optimum correction of the geometric deviations of the manufactured part with respect to its digital model, from the measured points on its surfaces. In the case of production by machine tool numerical control, there exist a link between the tool offsets and deviations of measured points. An incidence matrix which represents this link is obtained. In most cases, this matrix is not square and therefore not invertible, because there are more measured points as correctors to adjust. The Gauss pseudo-inverse is used to calculate the values of corrections to be made to compensate for measured deviations. Tolerances associated with the surfaces must also be taken into account in the incidence matrix. However, when the same cutting tool machine two surfaces with different point values, the resulting solution favors the one with the highest number of points, at the expense of the other surface which can remain not conform towards its tolerance. This paper proposes a strategy to rebalance the correction surfaces, and this regardless of the number of points and tolerance of each surfaces. A relatively simple tutorial example is given in the paper to enable tracking calculations

Optimisation of a stamping process by a design of experiment linked to a modal analysis of geometric defects

International audienc

Multivariate SPC for total inertial tolerancing

This paper presents a joint use of the T2 chart and total inertial tolerancing for process control. Here, we will show an application of these approaches in the case of the machining of mechanical workpieces using a cutting tool. When a cutting tool in machining impacts different manufactured dimensions of the workpiece, there is a correlation between these parameters when the cutting tool has maladjustment due to bad settings. Thanks to total inertial steering, the correlation structure is known. This paper shows how T2 charts allow one to take this correlation into account when detecting the maladjustment of the cutting tool. Then the total inertial steering approach allows one to calculate the value of tool offsets in order to correct this maladjustment. We will present this approach using a simple theoretical example for ease of explanation