Published 2/13/2009

Vision System Brings On-Machine Measurement To Ram EDM

Vision technology tailored to ram EDM allows shops to measure a part as it remains fixtured on a spark-erosion machine.

Editor-in-Chief, Production Machining magazine

This vision system allows mold makers to perform X-Y measurements while a workpiece remains fixtured to the bed of a ram EDM unit.

A number of shops use their CNC machine tools as measuring devices. Machines equipped with touch probes can locate parts or fixtures to speed setups, perform in-process measurement to gage machining accuracy or carry out post-process inspection of completed parts.

Now vision technology tailored to ram EDM allows shops to measure a part as it remains fixtured on a spark-erosion machine. Comparable in functionality to an optical comparator, the TolTec Microimage Measurer eliminates the need to remove an in-process part from an EDM unit, measure features off-line and then painstakingly relocate the part on the machine for additional operations. The vision system is available from the Consumable Products Group division of MC Machinery Systems, which is the exclusive distributor of the system for North America.

The 2D TolTec Microimage Measurer can prevent costly mistakes caused by inaccurate part repositioning after offline measuring. The heart of the system is a CCD camera that can be fitted with an Erowa, a Hirschmann, a System 3R or a universal clamping fixture. The vision system also includes measuring software and a high-resolution, 15-inch LCD monitor.

The camera installs in an EDM unit’s spindle either manually or via an automatic tool changer. A power supply is attached to the camera as is an RS-232 cable, which connects the camera to the monitor. An operator begins a measurement routine by viewing the monitor as he or she centers the camera at the edge of a part feature. After nulling the machine’s X and Y axis values, the camera is positioned to target the feature’s opposite edge. The measurement is recorded from the machine’s control.

A coaxial red light in the center of the camera indicates target position while a perimeter light illuminates the part so that it is clearly displayed on the monitor. The camera is available with 30X, 55X and 250X magnification lenses.

The company is developing a version capable of measuring Z-axis cavity depth as well as models for use on laser cutting equipment and machining centers.