Multi-point quality inspection for gearboxes
Top performance Saab Automobile gearboxes profit from automatic inspection using Cognex machine vision
Saab Automobile PowerTrain AB is a subsidiary of Fiat-GM PowerTrain and manufactures gearboxes for worldwide export to GM plants. For over 50 years they have been producing gearboxes for Saab cars and today do so at the rate of 700 units a day. The factory also makes gearboxes for the Opel Vectra, Opel Zafira and for Saturn in the US.
At one time Saab Automobile PowerTrain manually made inspections of the gearboxes before their delivery to customer plants. The manual inspection demanded quality control of 60-70 inspection-points on the gearboxes which was time consuming and not fully reliable. The other disadvantage was that many varieties of gearboxes were being manufactured with very subtle differences between them, which is a big challenge when using manual inspection. Customer demands for shorter and shorter lead times created the need for a more efficient and less time-intensive inspection. It became clear that automatic inspection was necessary in order to guarantee product quality.
40 seconds for complete inspection
A complete multipoint inspection of the 60-70 spots on the gearbox is made in 40 seconds with a vision-equipped robot. This means that several inspections are made per second. For the demanding conditions of the inspection application, Saab selected a solution based on collaboration between Cognex and their Partner System Integrator Svedvision Systems AB. This experienced and highly skilled robotics integrator developed a robot guidance and inspection cell that is perfectly adapted to the specifications of the project and is used for the gearbox application. The choice of suppliers for this solution was easy because it was based on the fact that Cognex and Svedvision have real in-depth knowledge of the automotive industry worldwide. Cognex has been pioneering the vision industry for 24 years and Svedvision Systems AB, founded in1988, have a long history of integrating machine vision.
The PatMax® software featured in VisionProTM (the PC-based development environment from Cognex) was integrated into the platform that handles both the robot and vision using a 3D-measurement unit developed by Svedvision using search, edge and ID-tools.
The application consists of:
• Inspecting all mounting parts that are visible from the outside
• Inspecting hole and screw threading
• Checking mounted screws and that they are fastened on the gearbox
• ID-reading on parts
• Gearbox label verification
• Gearbox ID Verification
No customer complaints in 17 months
“Saab needed to eliminate manual inspection, which is an unreliable solution compared to high-performance automated inspection“ says Ulf Svensson, Group Leader of Manufacturing Engineering Saab Automobile PowerTrain. “Automating the inspection process allows Saab to set a standard and demonstrate that money is being invested on improvements that are in keeping with our customer’s needs. In order to stay competitive we have to ensure increasingly shorter lead times and high-quality performance. It is important that we listen to our customers and be reactive to their concerns.”
Ulf Svensson continues: “Through the application a reliable and robust final inspection system of the gearboxes has been implemented. The inspection system adjusts itself to all types of gearboxes that are produced at this plant. The inspection system has been a good reference in the total quality management program that is implemented by Saab. Thanks to the fully integrated solution proposed by Svedvision Systems and Cognex, all gearboxes delivered are inspected and feature zero defects.”
The result of automating inspection at Saab Automobile PowerTrain AB in Gothenburg, Sweden has been no customer complaints in 17 months. This is virtually unheard of in the automotive industry.
There are other examples of vision use at Saab Automobile Power Train such as a vision system in the assembly department to check that critical parts are mounted. At Saab Automobile PowerTrain AB the automation of production is a reality and it is an important competitive element in this day and age. It is clear that the use of vision to check critical issues will be an efficient alternative to ordinary manual checks in the future.