Quality Applications

Cognex's Checkpoint Benefits Uses gaging and inspection tools to carry out the sequence of quality checks Records pass/fail data, including information about the type of defect found www.cognex.com

Vision System Ensures Quality of Mascara Brushes
Cognex's Checkpoint

Geka Brush, a German designer and manufacturer of cosmetic brushes and applicators, needed a machine vision system for inspecting its mascara brushes. Given Geka's demanding throughput requirements, automated inspection was necessary. Geka chose the Checkpoint machine vision system from Cognex.

 The shape of the brush, its length, the number of brush windings and bristles, and the thickness of the underlying wire had to be carefully measured in less than two seconds. Defects visible only on certain portions on the brush had to be examined from three different perspectives.

 To accomplish this, Geka developed a custom system that uses a rotating arm to first grip a brush by its wire and then rotate it at three 120-degree increments. The vision system's camera remains mounted in a fixed position and captures the image of the brush as it turns. Infrared backlighting illuminates the part, helping to create high contrast between the brush and background. The captured image is then transferred to the Checkpoint system, where various image analysis software tools are used to compare the image to a reference.

 A reference image is generated for each of the 30 styles of brushes. To create a model for each brush, the company milled synthetic brushes out of aluminum and then captured and stored images of the "master" brushes into the system's memory.

 The Checkpoint system uses gaging and inspection tools to carry out the sequence of quality checks during the image analysis. If defects are detected, brushes are instantly air-blown into a reject bin without stopping production. Defect-free brushes are dropped into a different bin and proceed to final assembly.

 In addition to performing the inspections at high speeds, the Checkpoint system improves Geka's process control. The system records pass and fail data for each brush inspected. For example, if the volume of bristles were unacceptably large, the trimming machine might be adjusted.

 Geka has Checkpoint systems at 11 stations throughout its plant, inspecting roughly 43,000 brushes per day. As a result, the company has been able to ensure that every mascara brush leaving its facility is free of imperfections.