NEW METHOD AUTOMATES RETAINING RING QUALITY CHECKS

A retaining ring is an engineered component designed to retain assemblies on a shaft or in a housing/bore. It meets performance expectations when critical design characteristics like free diameter and maximum section match catalog specifications. The operator or a QC inspector often takes these measurements manually during production using a tool or gauge for this purpose.

Although this method is effective, it loses its accuracy when the measurements are taken on smaller retaining rings. Given that some retaining rings are small enough to fit on the tip of a finger, it is understandable how accurate measurements can be severely hampered by the skill level of the person performing those checks and the tools employed. Rotor Clip Company, a worldwide producer of retaining rings and self-compensating hose clamps, has developed a way to automate this process and improve the accuracy of measurements taken on smaller diameter retaining rings. The company is equipping some of its stamping workstations with the Insight® Machine Vision System. The system is programmed with the specifications and tolerances for a particular retaining ring that is scheduled to run on a given stamping press. For example, a DIN 471 external retaining ring for a 3mm shaft (Rotor Clip DSH-3) would be programmed with the catalog specifications for Inside Diameter (ID)—2.7mm (Tolerance, +0,04/-0,15); Maximum Section—0,8mm (Ref); Lug Height—1,9mm (Max); and Lug Hole diameter—1,0mm.

When the operator needs to check these dimensions, he removes samples from the press and places them under a camera on a backlight unit. The camera takes a jpeg picture of the ring and the computer measures the pixels for each of the critical dimensions designated. It then converts this pixel count to numbers in millimeters or inches, which are then compared to the tolerances specified. The values are depicted on the computer screen next to the corresponding characteristic. A “Fail” message alerts the operator to any dimension that may be out of specification. There are numerous advantages of this type of measuring system.

• Measurements are more accurate. For a 25.9mm (1 inch) field of view, the resolution is accurate to .0127mm (.0005”). This is far more reliable than an operator relying on his eyes to read the results from a graduated gauge.
• Measurements are taken more quickly. Once the ring is placed under the camera, all measurements are taken within a fraction of a second.
• Timely adjustments can be made. With such a fast and accurate measuring system, the operator can make needed adjustments to the process before large quantities of non-conforming parts can be produced.

Most importantly, this technology assures the customer of receiving quality retaining rings that will perform in the application according to the catalog specifications.