Real time inspection of fast extrusion processes
15 April 2014
Wire and extruded products can now be inspected at speeds of up to 10m/s, with defects as narrow as a human hair being detected in real time.
Researchers at the Fraunhofer Institute for Physical Measurement Techniques IPM in Freiburg have developed an optical inspection system, called WIRE-AOI, that can detect defects in strip products (pipes, wires, rails, boards).
The inspection system detects micro-defects that are no thicker than a human hair at speeds of up to 10m/s and displays them on a monitor. The system marks the location of the defect, and stores the associated camera image in a database. This way, manufacturers of strip products can identify, classify, and document defects during production.
Four high-speed cameras deliver the images of the defects at the rate of 10,000 images per second, and processes them in real time. Special LED lighting produces intense bursts of light at a frequency of 10,000Hz, the reasoning being that the brighter the light and the shorter the light pulse, the sharper the image. At this frequency an object passing at 10m/s is virtually stationary for the purposes of imaging.
The system, which is currently being offered to operators of wire-drawing machines, is designed to cope with the rigours of the manufacturing environment, including excessive vibration and dust contamination.