Fully Automatic CMM For Machine Shops

Sheffield Measurement has introduced a new CMM (coordinate measuring machine) targeted at the shop floor measurement needs of machine shops. Called the Cordax Discovery, the fully automatic CMM is made to operate on the shop floor near CNC machine tools.

A primary design criteria for development of this new machine was ease of use. According to the company, the machine is made for use by machinists and other shop workers who have no metrology experience. Interface with the CMM is intuitive enough that anyone familiar with standard part drawing symbols can operate the machine.

When located on the shop floor, operators and machinists can verify part quality and check machine tool setups. Discovery is shop-hardened. It is made to operate outside a clean room environment.

No special site preparation is needed for this CMM. It does not use shop air. A standard 110-volt outlet supplies power to the CMM and its PC-based control. Accuracy is maintained by automatic temperature compensation, which is standard on the machine.

In use, this CMM can operate in a fully automated mode. It will perform all of the necessary calculations and move the measurement probe according to programmed instructions. To generate the program, an operator uses a remote joy stick to measure one part.

As the probe is guided around the workpiece's geometry and features, the operator touches the requisite measurement points with the probe creating the program. Subsequent parts in the batch can then be measured with the same
program.

Offline programs can be downloaded to the CMM's CNC in shops set up with DNC. Discovery will run programs written for other Sheffield CMMs. The PC-based CNC can also accept files in various formats if the shop's customers prefer to prepare measurement programs. It's a flexible system.

The new machine has a working volume of 20 inches X-axis, 24 inches in Y-axis and 16 inches in Z-axis. Resolution is 0.00004 inch displayed and the linear accuracy is 0.00020 inch in X and Y axes with 0.00018 inch in the Z-axis. Volumetric accuracy, using a 12-inch ball bar, is 0.00071 inch.

Shops of all sizes and types are feeling pressure from their customers to improve consistency and quality of the machining process. At the same time tolerances are being tightened across the metalworking board.

In many cases, just delivering good parts is not sufficient to satisfy documentation and SPC requirements. Shops need to demonstrate how their processes work. Sheffield's Discovery CMM is a flexible shop floor tool that can help shops satisfy customer demands for data and documentation. Most important, it's a machine that can be operated by existing personnel. Sheffield has priced this machine under $25,000.—GCK