Retina Systems Inc. (Seymour, CT) manufactures high speed, noncontact laser vision inspection systems for use in everything from the electronics to the aerospace industries. The company’s products include automated threaded fastener inspection machines that detect surface problems, missing internal or external threads, damaged threads and fasteners with mixed thread sizes. The systems scan each fastener vertically, while a horizontal beam determines exact part location. The inspection of the peaks and valleys in the thread creates a pulsing return signal that is picked up by a receiver-detector.

Studies have shown that human inspectors can miss as many as 20 percent of defective parts when operator fatigue sets in. Laser inspection systems, on the other hand, can gauge dimensions with much higher accuracy while eliminating inspection errors. Laser inspection systems are also much faster. For example, Retina Systems’ noncontact gauging machines can check as many as 850 parts per minute.

Recently, Retina Systems added a micrometer dial with a digital readout to its fastener inspector lineup, which makes it possible to adjust a single inspection system to analyze a variety of different parts. The idea was to take machines that had, until that point, been designed for a single part and make it possible to change them over to handle a wide range of sizes in a few seconds.

At the heart of this technology is the N-series linear slide from linear motion manufacturer Del-Tron Precision Inc. (Bethel, CT). The slides are used to support and adjust the systems’ lasers, and provide an accuracy of ±0.0005 inch, with repeatability of ±0.0002 inch. To provide even greater accuracy, Del-Tron engineers added a preload feature to the N-series, which increases accuracy to ± 0.0002 inch, all in a slide costing just $75.

Retina Systems now employs up to six N-series slides in each of its inspection machines to accurately measure fastener diameter, length and thread angles. With over 300 of these systems in the field, the slides have yet to record a single operational failure.

Because Del-Tron ball slides are lubricated during assembly and are self-cleaning in normal service, they require minimal maintenance. In fact, no additional lubrication is required, except for applications involving speeds above 1,800 inches per minute or continuous high loading.

For more on automated fastener inspection, call 203-881-1311 or

For addition information on linear motion, call 800-245-5013 or