Dakota is the name of a vision system used for the inspection of polyurethane blocks such as those used for the manufacture of car seats. This application has been developed due to the close partnership between GIPS Vision and STEMMER IMAGING France and provides return on investment for the customer through a more efficient inspection process, a reduction in the use of raw materials, and has the added benefit of protecting the environment due to a lower material requirement.
The development of the Dakota system began in 2012 and has since been developed to its current state. It has a proven track record of performance and extension options from different foam production sites for car seats.
Frédéric Equoy, Founder and CEO of GIPS Vision, who played a key role in developing the Dakota system, is pleased to explain: „These systems have already been installed successfully in several countries worldwide and have proved to be reliable and fast 3D systems for the quality control of injection moulded polyurethane foam blocks.“
The system helps in the production of polyurethane foam parts that are used for car seats. In this case, the components are inserted manually into the mould. Equoy explains „This delicate process cannot be automated. Given the high rate of the line, this manual process can lead to errors such as missing or misplaced components. These errors are unacceptable for the end product and hard to detect once the foam block has been produced.“
The Dakota 3D inspection system is designed for detecting errors before they occur. It is applied immediately before mould injection and thus avoids the production of faulty foams and prevents a significant waste of material. Equoy describes the principle: „On the foam production line the Dakota system comes immediately after insertion and checks directly before injection whether every component in the mould is inserted and well positioned and depending on that validates or declines the next step of foam injection. This prevents the production of incomplete parts.“
This method leads to a number of benefits: First of all, Dakota reduces scrap. In fact, it significantly saves material which would otherwise be completely wasted as a solidified faulty part which cannot be used again. Although the parts that are manually inserted have only little value, faulty ones can no longer be used either.
With the Dakota system visual controls of fabricated foam parts are no longer necessary, thus saving human resources on this process stage. Another advantage for users is the reduction of customer complaints due to poor quality and other returns of supplied products. In total, the customers’ ROI and production reliability increase significantly when using the Dakota system in their manufacture.
In principle, the 3D imaging system is based on laser triangulation. The injection mould is scanned by a laser illumination from Freiburg-based manufacturer Z-Laser. An Automation Technology high-performance camera captures up to 1,000 laser profiles per second with a width of 2,000 pixels. The known angle between camera and laser level allows extracting the height information from the laser profile based on exact calibration and adapted to the line and mould configuration.
In this way, the system creates a 3D image of the mould and its inserts, which allows for their localisation in three dimensions. The evaluation of the 3D image allows a reliable conclusion as to whether all parameters meet the requirements and the injection moulding process can be initiated.
For every slide Dakota inspects the components or inserts which are placed into the empty mould immediately before injection and need to be in the completed foam block. These inserts can be composed of different materials, sizes, thicknesses, colours and forms: metallic wires, plastic clips, fabrics, foam blocks, that are important for the subsequent correct functioning of the car seats.
Dakota offers a dedicated, graphic and easy-to-use human-machine interface which allows defining test points and configuring the applied tools. Up to 999 different mould specifications can be programmed to Dakota's database and up to 999 spot checks can be carried out on every mould.
Moreover, the system can be adjusted to moulds and slides of different sizes and to variable speeds of the production line. Frédéric Equoy cites an actual application example, where the Dakota system checks moulds with a size of 1700 mm corresponding to the total size of a complete rear seat on a conveyor at a speed of 14 m/min.
According to Frédéric Equoy the system’s performance limits are far from being reached. „This concept is not only limited to the automotive sector, it is suitable for many other industries, too. We plan to extend the application fields of the Dakota systems in the near future.“
From a purely mechanical perspective, the system is flexible enough: Just recently, Dakota was successfully implemented in a turntable production line, where the individual production steps are linked over a circular conveyor.
Successful as a team
The Dakota system was achieved thanks to the close cooperation between GIPS Vision and STEMMER IMAGING in France.
Frédéric Equoy sums up: „Our partner supported us with extensive know-how and significantly helped us in defining the 3D imaging system and choosing the optimal components. The integration of the Dakota system was not easy at all due to the rough injection moulding environment. But GIPS Vision specialization in this field combined with STEMMER IMAGING‘s expertise in machine vision combined to create this powerful vision system that saves the users’ money and leads to a more environmentally friendly use of raw materials.“