Témoignages

At the heart of power electronics, world leader in its sector, LEM offers innovative and high quality solutions for the measurement of electrical parameters. Its flagship products - current and voltage sensors - are used in many applications for industry, traction, energy and automotive. For its part, Qualimatest is the leader, in Switzerland and France, in automated quality control solutions and equipment. They can be autonomous or integrated into an existing machine. The software and equipment are made by the Qualimatest team to best meet the needs of customers. Qualimatest has extensive experience in the watch, automotive, medical and rail industries.

Thirty years ago, the founders of LEM and Qualimatest, MM Jean-Pierre Etter and Luc Haenny were the first actors in this collaboration. Our companies have been collaborating regularly for more than 10 years. To date, about 20 projects have been carried out jointly.

The products to be tested are current sensors. The objective is to control the geometry and the spatial position of the pines.

At the origin of the project, for the first time, we decided that Qualimatest develops and realizes standard "off-line" control modules integrating measurement, mechanics and electrical. This organization allows individual validation outside the line of systems before installing them on the automatic line. This organization has allowed the definition of a standard that can now be reused while optimizing costs and deadlines.

To significantly reduce false rejects, an algorithm called "Best Fit" developed by Qualimatest, LEM and Pillet Consulting has been implemented, it combines measurement results and statistics. The main idea is to calculate the position measurement reference according to the actual position of the pins in order to find the minimum error. This technology optimizes control to reduce the scrap rate.

LEM's teams have developed and manufactured a fully automatic production line of large-scale current sensors. The design and construction were carried out entirely in Plan-les-Ouates for deployment in Switzerland and Bulgaria. Two demand-specific measurement stations (QMTCheck-M4U) developed by Qualimatest control the conformity of manufactured products

• A 2D ½ measurement station in traditional optics with 3 cameras for the spatial geometry of pins with a measuring accuracy of 10μm
• 3D measurement station in white light interferometry for coplanarity of pins with a measuring accuracy of 10μm

Quality control is done directly on the production line. The advantage of this configuration lies in two points: 100% of the parts are controlled and the measurement results and their associated statistics guarantee a continuous correction of the production parameters in order to guarantee maximum productivity.

The measurement stations embark the Qualimatest QMTMesure-Expert software:

• High precision measurement by subpixel processing and geometry modeling
• High level of robustness of measurement with the removal of imperfections by filtering
• The measurement of complex features by geometric construction and calculations
• High-level features for performance and ease of use

This project incorporated several challenges including cadence, measurement accuracy and 3D control. The project is a success because all the objectives have been achieved.

Regarding the integration of innovative 3D technology, it has met the expectations in terms of metrology and industrial strength has been satisfactory for more than 24 months.