Case Studies: The Automated Metrology Advantage
Today’s rapidly changing market conditions and ever-increasing global competition force manufacturers to continuously optimize processes and improve customer satisfaction. Time-pressed customers are demanding faster service without having to sacrifice product quality.
“Today, it’s all about just-in-time manufacturing and speed-to-market capability,” says Arvin Kumbakonam, mold design engineer at Intralox Inc. (Harahan, LA). “That is why we believe highly in automation. It is a vital component of our strategy.”
Intralox manufactures modular plastic belting products for the food processing, beverage container and material handling industries. At its 335,000-square-foot facility in New Orleans, the company manufactures more than 400 different types of belts. It began manufacturing modular plastic conveyor belting in 1971 and since then has remained a large producer of this technology.
Intralox produces thousands of graphite electrodes per year that are used to make the molds for the various types of belts. Before the company purchased the Contura coordinate measuring machine (CMM) from Carl Zeiss IMT Corp. (Osseo, MN), it was using measuring devices such as optical comparators and dial indicators to inspect molds.
“As mold cavities became more complex and difficult to inspect, the whole process became too time consuming,” says Kumbakonam. “We were not able to measure geometries on certain molds and electrodes. In addition, we knew that we had to automate our processes to maintain the flow, so we made the decision to buy a CMM.”
This would allow Intralox to check the geometry of the parts more quickly and speed up the process. “Those were our basic requirements at that time,” says Kumbakonam. “After we started using it, however, we discovered additional benefits that would help us optimize our processes even further.”
Expectations ExceededBefore making the investment, Dave McClendon, mold maker at Intralox, wanted to be certain to select the CMM that would offer the most benefits. “We selected some of the key parts and sent them to several CMM suppliers for testing,” says McClendon.
A few weeks later, McClendon and Kumbakonam attended demonstrations to see the capabilities of various CMMs firsthand. They were impressed with the results they saw during the Contura demo at Carl Zeiss. They were most impressed by the contour scanning capabilities of the Vast XT sensor. With this, Intralox would be able to accurately measure geometries and achieve repeatability among measurements. Intralox also would be able to share information back and forth between PRO/E and SolidWorks and gain computer-aided design (CAD) exchange capabilities.
Unexpected BenefitsWith the Contura CMM, Intralox can inspect deep inside of parts to check concentricity, roundness and straightness of holes. “We did not have that capability before and it is vital to this procedure because of the molding process,” says McClendon. “We put a core rod inside each mold cavity, which creates geometry on the final product. This requires us to hold very tight tolerances of about ±0.0002 inch.”
With the ability to perform in-process inspection of the molds and keep records of all data, mold maintenance can now be scheduled at regular intervals and replacement parts can be built on time, which results in less downtime.
Another benefit Intralox discovered is the ability to reverse engineer some of the plastic parts produced in the molds. Plastic parts sometimes have processing inconsistencies that have to be overcome by reverse engineering. Engineers now are able to inspect the piece and remake cavities to ensure that they meet set specifications. “That helps us in a great way,” says Nick Judice, mold design engineer at Intralox. “When you realize that you have a nonvalue-added process slowing down your manufacturing process, that is when it’s critical to automate the process.”
The Calypso CAD-based software has provided Intralox with several benefits, in particular the Calypso parametric programming capabilities (PCM). Using the Calypso DLL interface, operators write Visual Basic programs that help store and retrieve information from the database. Another benefit of the software is the ability to set up multiple operator levels. After the programs are created, it is easy for operators to begin the inspection process.
Incorporating LeanThe use of CMMs has increased throughput of high-precision measurements, thus decreasing time spent on quality control. At Intralox, employees incorporate lean into their day-to-day activities. In an effort to decrease waste, they rely heavily on automation. Through this process, Intralox has automated the CMM and its programs with a mix of in-house custom applications and PCM to yield more robust measurement data and reduced downtimes.
“The CMM offered us a lot more than we expected. A lot of our measuring has grown,” says McClendon. “For example, we have many parts that are built by outside vendors. We never really took the time to measure the incoming parts. We now have the capability to inspect incoming parts, which allows us to verify the specs and make sure that our vendors hold the same tolerances that we do.”
Manufacturing Improvement“Having the CMM totally changed the way we think about manufacturing,” says Kumbakonam. “It is not only a quality control device for us; it also is a manufacturing improvement device. It gave us information about what is going wrong in our manufacturing process and we were able to eliminate inconsistencies.”
“The cutting tools we used in the past used to wear, because graphite is milled at very high speeds,” says McClendon. “We were able to specify better cutting tools and make better decisions on which tools to buy, allowing us to maintain the required accuracy on our graphite parts. Using the customized template-based programming, our CMM is able to check the geometry of the electrodes in a matter of minutes.”
The CMM allowed Intralox to enhance product quality and reliability. The company was able to accurately measure data during production cycles prior to final assembly, allowing less custom manufacturing and more reliable tooling. The tolerances range from ±0.005 to ±0.0002 inch. While previous measurement techniques were able to reach these tolerances, Intralox paid a heavy price in regard to measurement time.
With the advanced features in Calypso, Intralox also was able to improve the form grinding process. This is a difficult procedure considering the intricate part geometry of the steel, particularly if an accuracy of ±0.0002 inch has to be maintained.
“We place a form on a grinding wheel, take a piece of graphite, grind it and measure it,” says McClendon. “After that ±0.0002-inch limit has been achieved, we begin form grinding the steel. Calypso has helped us maintain our tolerances a thousand fold and was able to help us automate measuring form geometry in steel or in graphite.”
“The Zeiss Contura has automated the complete measuring process and reduced our measuring time,” says Judice. “We were able to eliminate nonvalue-added processes and maintain flexibility without sacrificing product quality. We now have a closed-loop manufacturing process.”
Carl Zeiss IMT Corp.