Machine Design

Vision system runs rings around manual measurement methods

A vision system dramatically boosted speed and accuracy for a manufacturer of retaining rings, letting it gauge supersmall dimensions.

Small retaining rings sit on a light table for imaging by the Cognex In-Sight 1000 machine-vision sensor.

A view of an imaged retaining ring shows typical measurements the vision processor makes. The vision system stores individual measurement programs for each ring type which operators call up as needed.

Rotor Clip Co. Inc. in Somerset, N.J., had trouble measuring retaining rings it made with diameters below a half inch. The typical approach was to manually check rings with vernier calipers, a procedure that was time consuming and error prone. To speed the process, Rotor Clip installed an In-Sight 1000 machine-vision sensor from Cognex Corp., Natick, Mass. Operators now mic a ring to gauge its thickness, then place it on a back-lit screen for the vision system to have a look.

The operator brings up a measurement program corresponding to the size of the ring. The In-Sight system captures a ring image and sends it to a built-in vision processor where software tools aid in its analysis. Typical features measured might include inside and outside diameter, minimum and maximum sections, and lughole dimensions.

A special pattern-location tool called PatFind verifies whether the part is present or out of view, then applies a virtual fixture to register the part for different measuring functions. Other software tools size up features such as diameters and segment sizes. A color LCD built into the inspection station gives operators a realtime view as measurements progress. A custom user interface shows measured ring dimensions and pass/fail lights signaling when a part is out of tolerance.

An Ethernet link connects the inspection station with micrometers so thickness measurements can upload into the In-Sight program. The two kinds of data then go to a quality-assurance database for statistical studies and to archives maintained for tracking down any problems that arise in the field. The Ethernet facilities also let supervisors diagnose measurement problems remotely and download software upgrades.

Despite no previous experience with vision systems, operators find the new Cognex equipment easy to use, say Rotor Clip officials. And ring measurements that once took 20 min now finish up in five.

Cognex Corp.,
Rotor Clip Co. Inc.,

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