Vision Systems Ensure Saw-Blade Perfection

At Switzerland-based saw-blade manufacturer Scintilla, a Bosch Power Tools division, a high-performance vision system ensures that jigsaw and reciprocating saw blades leave the production plant free of defects. As many as 700 different models of jigsaw blades, all with different paintwork, imprints and shapes, are produced at the plant, and each requires complete inspection. To automate the quality-control process, the company invested in a vision-based solution supplied by Cognex (with U.S. operations in Natick, MA), installed by Swiss integrator Compar AG.

In the finishing area of the Scintilla plant, operators insert eight fabricated jigsaw blades into a fixture mounted on a rotary transfer machine, which positions the blades for inspection. During the first phase of inspection, the vision system inspects the base paint for color and discoloration, as well as for the presence of dirt, scratches or fine lines down to 0.2 mm in size. A second inspection phase then checks the pad imprint on the saw blades to determine the quality of the printed text or graphics.

An important feature of the vision system: The individual shapes of each blade type need not be manually positioned and adjusted. Rather, the shape of the saw blade need only be taught to the system once and then saved. The individual characteristics of each blade—edges, dimensions, shapes, angles, arcs and shades—are isolated and identified. The three-dimensional relationships between these features of the learned image then are compared against the real-time image.

The Cognex quality-control station operates on a three- to four-shift basis and checks 60,000 saw blades each day. The machine runs on a 4.5-sec. cycle, with visual inspection taking 1.8 sec.