100% Quality Inspection with State-of-the-art PC-controlled Image Processing
Cognex Vision Software Ensures the Quality of Ready-to-assemble Furniture Components at Ikea
- Fig. 1. Inspection system with Cognex technology inside
- Fig. 2. Roller conveyor in front of the inspection zone with Cognex cameras
- Fig. 3. Rapid feeding of various boards, which are scanned without decelerating by the Cognex 2-GigE high-resolution camera (left-hand image, bottom, centre)
- Fig. 4. The analysis data generated by standard PC and displayed instantly on the monitor is used for assessing whether or not the lamination has been applied correctly
- Fig. 5. The system seen from behind with view of the control cabinet
Amongst other products, Ikea Industry Poland produces furniture boards that are automatically film-laminated. The edges are particularly critical in this process, where it is necessary to check precisely that the quality is OK. This fully automated inspection is being carried out with vision software from Cognex.
Not everyone has furniture from Ikea, but virtually everyone knows the brand. This success is a result of the concept of selling the furniture as self-assembly kits, where customers assemble their pieces of furniture themselves following a set of instructions. In addition, even as far back as the mid-1960s, the product warehouses became showrooms – also a strategy that has led to success, and equally so the low-price policy and modern marketing concepts. Technologically, the Swedish company has pursued innovative paths from the very outset. Even in the early 1970s, IKEA recognised the importance of automation.
Decorating furniture by lamination
The Swedish company has around 12,000 items in its product range. One well-known product is the "Billy" shelving system. Its shelving components are made from plastic-coated, veneered particle board. The edges are covered over by glued on plastic strips. The Billy shelving systems are currently available in a range of different colours and finishes. This is just one prominent example from the vast Ikea world, though the production of the various furniture components is often identical. A key step in the production process is the lamination. This entails an attractive film being applied to the boards as a means of decoration.
Furniture elements are produced using lamination also at Ikea Industry Poland. A laminating machine is used for applying a film with glue to both sides of the boards. A cutting machine subsequently trims the excess material at the edges to the correct length. Even if just a few process parameters are not kept to absolutely precisely, this can quickly lead to the film not being glued on properly. And this spoils the visual appearance particularly at the edges of the boards.
The production process is very flexible in terms of colours and types of lamination.
Currently, Ikea offers about ten different designs, such as birch, oak, coloured black with wood texture, and slick colours as white, black or pink. In sum, every day approximately 3,000 boards are being laminated during each shift, resulting in an average output of 375 pieces per hour.
Manual inspection is not an option
No defects whatsoever are allowed in the finished products. In theory, therefore, a skilled worker should perform a visual inspection of the board edges on the conveyor belt. It has transpired, however, that manual checking is not effective. A worker alone cannot check both sides of the board at the same time – not to mention the fact that it would be hardly possible to spot all the defects with the conveyor belt travelling at speeds of up to 52 m/min.
Manual checking would also be hazardous for those performing the inspections on the conveyor belt, since they would have to get very close to the moving parts in order to spot defects – which could lead to injuries and accidents. Consequently, the systems integrator Automatech has developed a machine for checking the laminated boards with an inspection system based on machine vision technology from Cognex.
Automatech is a highly specialised Polish engineering company with over 20 years' experience in industrial automation. The systems integrator supports its clients with services in addition to components and systems from the world's leading manufacturers – such as Cognex, for example. A large number of the solutions developed by Automatech are custom-built to the specific requirements of industrial clients. This is why virtually all the projects are one-offs with a prototype character. The solutions also include application-related systems for quality control – which is why the company was ideally suited for the task at IKEA.
For Ikea, Automatech has devised a fully automated inspection facility, which allows a 100% quality inspection to be carried out on shelving boards. The machine vision system is based entirely on the technology from Cognex. By way of example, the Cognex Designer software and VisionPro toolbox are employed. On the hardware side, a CIO-24 card and multiple 2-GigE high-resolution cameras are used. The components are installed inside a machine enclosure with lighting through which the boards pass in rapid succession. The system developed for IKEA inspects the quality of the decorative film on both sides of the board without manual intervention.
The system has been designed specifically for the wood-processing industry in order to minimise waste owing to faulty edges. IKEA's prime aim was to detect and eliminate the following defects: excess glue, incomplete lamination, detachment of the film. Only a few boards per shift fail the checks.
Defective boards are being processed by cutting off the parts which have been identified as failures. All defective parts will be marked as damaged and sorted out manually. In this application, it has been most crucial for IKEA to avoid that boards with defective edges can enter the regular production process and to eliminate the need for constant manual checks.
In the Ikea application, the 2-GigE Cameras (surface scan, 60 fps) and lighting modules are being moved by precision servomotors, since the width of the boards is variable (600 to 1300 mm) and the inspected area has to be approached and brought into focus quickly and precisely. This data is processed immediately after the images have been recorded. The CIO-24 card is the I/O card recommended by Cognex when implementing machine vision solutions on industrial standard PCs. In addition, the 4-port GigE Frame Grabber Cognex 8704e permits a high processing speed even with four connected cameras.
On the software side, Cognex Designer facilitates rapid creation of complete machine vision applications. This enables users to immediately enjoy the full capabilities of the accompanying VisionPro software – a smart tool that ignores noncritical changes in the appearance of test areas and which concentrates entirely on critical features. As such, it is the perfect machine vision tool for optimising and processing images. Various calibration tools correct lens distortions, camera rotation and tilt.
On the basis of these Cognex components, Automatech has developed a highly efficient system for streamlining the inspection process at IKEA. It cuts waste from production and gives the furniture giant the certainty that its products fully satisfy the quality requirements.