Pick up the CMM Pace

Upgrades, new features, and additions can ease bottlenecks

FlyScan from Zeiss measures in a single path.

A short travel path of FlyScan from Zeiss results in 40 percent time savings according to the manufacturer and lets programmers choose a single path rather than several segments. It allows direct scanning where recesses are present and captures the measuring points in edge areas. Photo courtesy of Zeiss.

Production continues to get faster. Features continue to get more intricate. And proving accuracy continues to be paramount. This trio can lead to a backup at the end of the line. A queue of parts waiting for their turn on a CMM can chip away at overall productivity.

Squeezing more from the CMM you already have can alleviate the inspection bottleneck without adding an entirely new system. Updating software, adding automation, and incorporating upstream metrology can speed the measurement planning process, reduce the amount of data points to be measured at the end of the line, and add capabilities that translate into reducing CMM bottlenecks and a rapid ROI.

“Most CMM structures are serviceable for a number of years and they are pricey,” said Paul Gane, CMM business manager for Renishaw. “You can invest in some of the new technologies as retrofits and improve your accuracy and speed.”

Smooth Moves

Touching and scanning take a certain amount of time, but moving from one data point to another is a different story. Motion control technologies are increasing the speed between measurements. The probe is programmed to approach the part’s surface by the shortest path possible, the software looks ahead at the go-to points, then blends in the move to the next data point via the shortest path. The result is smooth, continuous, time-saving motions.

“New software is dramatically reducing the time it takes for CMM moves between measurements. It can optimize the movement of the sensor to go directly from A to B to C instead of going to a home position between each measurement. We saved 50 percent of measuring time just by incorporating this ability,” said David Wick, product manager, Industrial Metrology Business Group, Carl Zeiss Industrial Metrology. “The actual time the probe is touching the workpiece hasn’t changed.”

He described another software advantage that can help production and reduce end-of-line delays for companies with multiple locations. “This software allows a company with multiple plants to measure the same part at its various locations and compare the results in real time. It takes the measurements, formats them as the customer desires, and creates charts and graphs that show how each plant is doing. If you can quickly analyze how your results are trending, you can anticipate and/or quickly correct any problems. That helps production as well as reduces measurement bottlenecks.”

Software advancements and graphic displays have made programming easier, which translates into faster. Standard reports for aerospace, automotive, and other industries that are inherent in software packages zap the burden of formatting reports off the to-do list.

Gane said, “CAD-driven programming reduces development time and can be done offline, which boosts CMM productivity. The reporting is graphical rather than tabular, which makes it easier to interpret the data so response can be faster.”

Flexible Scans

Rotating an entire table can be a time drain. Rotate the scanning sensor instead. “We have a specific rotating scanning sensor that measures a workpiece from a number of sides without using a rotating table. You can index the angle of the sensor relative to the CMM so it rotates in 15-degree increments. It can go around the sides of the workpiece and rotate a bit so it measures an opening, goes in and out, up and over for another measurement. You don’t have to change styli or move the workpiece,” Wick said.

Another bottleneck reducer, Wick added, is setting up multiple parts for one measurement process. “Depending on the size of the workpiece, once the program has been optimized, multiple pieces can be set up on the CMM and measured as a batch. The best economy is if they are all the same piece, but they can be different. You would have to load the program or the second part, but you would still save setup time.”

REVO®-2 5-axis technology from REnishaw measures an engine block.

Renishaw’s REVO®-2 5-axis technology synchronizes the motion of the CMM and head axes to ensure accuracy during increased measurement speeds. Photo courtesy of Renishaw.

Upgrading automation to 5-axis scanning for complex parts or a 3-axis scanning sensor or trigger probe with stylus changing can improve CMM productivity. Gane said, “Improving automation where cycle times are long or large numbers of components must be measured can alleviate throughput problems. With the 5-axis technology, data collection is much faster, calibration time is shorter, movement between features is faster, and fewer stylus changes are required.”

Healthy Equipment

CMMs with built-in intelligence to monitor their own health help manufacturers keep the equipment at peak performance and avoid unplanned downtime. Operators are notified if the machine is operating correctly, if service is needed, and if the time is approaching to schedule maintenance. These automated prompts save operators from having to micromanage the machine to ensure accuracy and keep the measurements going.

When a problem does arise, the ability for service technicians to remotely access the customer’s intranet to review the machine’s history helps with a quick diagnosis and, hopefully, correction.

Upstream Measurement

The final check to ensure that each part meets specifications is traditionally located at the end of the line. Assuming that the measurements are within tolerances and the CMM reports prove compliance, all is a go for shipping. But a noncompliance problem identified at this point is expensive or impossible to fix. The investments in the material and production might have been wasted and the component becomes scrap.

Data from upstream, mid-production metrology can verify that all is good or point the way to corrective actions before the part moves on to the next process. And portable devices like white light or laser scanning systems positioned along the production route can reduce the CMM work load.

Joel Martin, product manager for laser tracker product line at Hexagon Metrology, said, “There is a lot happening on the portable metrology side to make end checks easier, quicker, and more effective. If you incorporate metrology upstream, you have more mobility as to how to use the information to make production corrections.

“Whether downstream metrology is used for individual parts inspection as an SPC [statistical process control] or as an every-part inspection quality control, information from those technologies can be fed into the SPC of the manufacturing process allowing quality to drive productivity.”

Martin continued, “And based on in-process information, you may not need 100 percent inspection at the end. That opens up time on the CMM. Your statistical process control may be so well done upstream that a final check may be needed only on one out of every 10 pieces or specific features rather than 100 percent. Focus on CMM as one piece of the quality control puzzle.”

www.hexagonmetrology.us

www.renishaw.com

www.zeiss.com/metrology