Production Testing of Sunroof Systems
Sound and vibration are growing in importance as critical factors in product quality. Therefore, manufacturers are required to perform noise and/or vibration quality testing prior to shipping a product. The proper implementation of such a test is a significant challenge – one that can offer a very large return on investment. To address this challenge, Brüel& Kjær has developed a turnkey system designed to interface with production test standards and perform all the needed sound and vibration tests to verify product quality. The resulting PULSE™ Production Test System provides repeatable, calibrated, objective sound and vibration measurement and evaluation. Inalfa Roof Systems use this system to perform vibration tests on their sunroofs. Inalfa needed a product quality evaluation system that would meet the requirements of their high-end, luxury vehicle customers. Brüel& Kjær was able to provide a superior solution.
Inalfa Roof Systems is one of the world’s biggest providers of vehicle roof systems for the car and truck industries. Inalfa designs, develops and manufactures sunroofs and open-roof systems for the automotive industry. With Headquarters in Venray, The Netherlands, Inalfa also has facilities in Italy, USA, South Korea, China, Brazil and Japan and employs 1700 people worldwide.
Auburn Hills Facility
Inalfa’s 12-year old Auburn Hills Plant in Michigan, along with a smaller facility in Grand Blanc, Michigan, USA, produce the majority of the North American sunroofs. The Northern American Technical Center in Auburn Hills, Michigan, USA is where the Northern American roof systems are designed, assembled, tested and inspected. Most Inalfa customers are Original Equipment Manufacturers (OEM) and include GM, Daimler, Ford, Mitsubishi, Nissan, BMW, Chrysler and Audi, but there is also a small after-market demand. At Auburn Hills, 300 people work in two shifts on eight production lines with a further line to be added later this year. The production lines are designed locally and Inalfa’s R&D group has Production Test Advisor (PTA) viewer licenses so that they can analyse historical data. Brüel & Kjær’s PTA system is now standard at this facility while Inalfa’s Headquarters in Venray has a Brüel& Kjær PTA unit on test. Production test systems are also being planned for Inalfa facilities in Korea and Brüel& Kjær will, ultimately, become the Inalfa global standard.
A typical sunroof has from one to three DC motors (with the exception of Audi, which has four), and the glass assembly moves back and forth on side rails. As sunroofs have grown in size and complexity to include multiple panes of glass, motorised sun shades (rollo), and the need to manufacture multiple models down the same assembly line, the PTA systems have grown from a few channels of data acquisition to six channels with multiple removable tool sets designed to be automatically swapped for each model run down the same line. A typical PTA system consists of a PULSE B-frame with four, uniaxial DeltaTron® Accelerometers Type 4514-B located near each motor and in the middle of each side rail. These measure the vibration from the DC motors. In addition to the vibration measurement, a current probe clamp is also installed over the power lead to the sunroof, and the signal used to determine the RPM of the motor. The test takes about one minute. On average, the throughput is one complete sunroof system every three minutes on each production line.