Until now, machine-based surface inspection methods have checked visual quality by means of direct or transmitted light in conjunction with a camera system. When it comes to the automated inspection of reflective and smooth surfaces, however, these methods involve problems. The resulting reflections need to be either eliminated or included in the measuring process. Consequently, complex lighting conditions using polarized light or fringed projection in a darkroom are required, or the objects need to be positioned with high precision and completely shock-free. Whichever solution is employed, neither permits an automated 100% in-process inspection.
The German company ELCO-PRO GmbH & Co. KG in Dortmund decided to take up this problem in cooperation with the University of Karlsruhe. Their image processing solution, called VisionFlex, allows the non-contact quality control of reflective or high-gloss parts by 100% in-process inspection. This means that inspection can be performed at the speed of the production run and is largely unaffected by position changes, shock, or extraneous light.
The VisionFlex system from ELCO-PRO is based on the HALCON image processing software and on a USB 2.0 industrial camera of the uEye® family from IDS Imaging Development Systems. IDS offers over 40 different models with CMOS or CCD sensors. ELCO-PRO’s application uses a UI-1440-M (1280 x 1024 pixels, CMOS monochrome) which, like all cameras of the uEye® family, provides a very compact design, fast frame refresh rates and excellent software integration.
The camera series, whose smallest model is only 34 × 32 × 27.4 mm in size, offers advanced performance. At a resolution of up to 5 megapixels, the “minis” achieve a frame refresh rate of up to 75 frames per seconds in full-frame mode. Far higher frame refresh rates are possible in the Area-of Interest mode (AOI). Cutting-edge features such as windowing, binning, sub-sampling and image mirroring in the x and y directions complement the scope of functions. Thanks to the USB 2.0 interface, the camera does not need any additional hardware and can be connected immediately to any laptop or PC.
VisionFlex reliably detects dents, bumps, inclusions, scratches, pimples and pits in specimens from 5 to 5000 mm. Polishing defects and striae can also be identified and displayed on the screen. In addition, the system tells a defect from a speck of dust or other contamination. It has replaced the human eye in high speed inspection.
VisionFlex performs image evaluation using the proven HALCON image processing software. This software combines the advantages of a flexible architecture with the possibility of quickly developing various image processing and analysis applications. The uEye camera provides the corresponding interface to HALCON as well as to many other standard machine vision programs, such as ActivVisionTools, Common Vision Blox or NeuroCheck.