Scanning Technology Optimizes Measuring Process For Manufacturer of Aerospace Components

Reliable and consistent performance is essential in any industry when it comes to ensuring customer satisfaction and increasing the pool of high-yield customers. For Pratt and Whitney, a manufacturer of aerospace components, reliable and consistent performance of their coordinate measuring machines (CMMs) proved to be a decisive factor in achieving highest customer satisfaction levels and operating profitability.

Pratt and Whitney, a United Technologies Company, designs, manufactures and services aircraft engines. Its North Berwick, MN parts center employs around 1,622 people and manufactures a variety of jet engine components ranging from bearing housings to stators, airfoils and vanes. Customers include commercial airliners and the military. The plant's primary role within the company is to cost-efficiently produce high-volume parts.

At Pratt and Whitney, CMMs have been an integral part of the manufacturing process from the very beginning. Shortly after the facility opened its doors in 1979, the company purchased several WMM 850 CMMs from Carl Zeiss IMT Corporation that were dedicated for the inspection of airfoils. Over time, the company added a number of new product lines such as bearing housings and blade seals and with that, additional CMMs, including a PRISMO and an ECLIPSE from Carl Zeiss. "In 2004, our customers required us to certify our manufacturing processes," says Marcel LaBrecque, project manager. "That's when we started our process certification initiative, which is an element within our ACE system." ACE stands for Achieving Competitive Excellence and is the proprietary operating system at United Technologies (UTC) locations worldwide. It was created to ensure world-class quality in products and processes. UTC facilities and subsidiaries are using ACE to improve quality and customer satisfaction while lowering cost.

Retrofitted MC850 measuring a support assembly.

TIME TO UPGRADE

The process certification initiative revealed that the existing CMM infrastructure, consisting mainly of various older operating systems, outdated algorithms and touch probing technology, had an adverse effect on accuracy and repeatability. A comprehensive GR&R (Gage Repeatability and Reproducibility) study was performed on several CMMs to assess their measuring capabilities. While the CMMs clearly maintained accuracy, results varied from machine to machine. "We were not able to provide our customers with consistent and reliable measuring results," says LaBrecque. "The tighter the tolerances that we had to meet, in one instance +/- .0005 in., the more challenging it became in terms of getting correlation between one system and another. We were just not able to cost-effectively achieve these accuracies with touch probing technology." LaBrecque knew that it was time to upgrade and that this step involved additional research and testing to justify the investment. It was the results of this initiative that prompted them to look for alternatives that would improve their measuring capabilities.

Measuring parts with Calypso has become an easy task for operators Myron Elbrader and Marc Hamel.

SUCCESS WITH SCANNING AND CALYPSO

LaBrecque had heard about the benefits of Calypso CADbased software and scanning technology from Carl Zeiss through various literature and online forums. He decided to have Carl Zeiss perform a GR&R study on one of the parts using Calypso software combined with scanning technology. The study produced significantly better results than the existing CMM infrastructure. In addition to a drastic improvement in CMM resolution of almost 500%, the report also showed that the desired accuracy of +/- 0.0005 in. could be achieved with VAST scanning technology — previously one of the biggest challenges when using touch probing technology. With VAST, operators are able to check a wider range of feature tolerances including form, size and location. VAST scanning was found to be ideal to measure their complex part geometries.

The decision to upgrade the CMMs was made and at the beginning of 2005, the first MC850 was upgraded to VAST Scanning technology and Calypso. The remaining 12 CMM retrofits were completed by March 2006. In addition to upgrading the existing CMMs, the group also decided to purchase six more ZEISS CMMs, including a SPECTRUM, a VISTA and four CONTURA to handle the increasing workload resulting from additional product lines.

The success was not only evident with the migration to scanning technology and Calypso software, but also with the purchase of the CONTURA CMMs with the RDS head. "In the past, we had been using the PH9 and PH10 probes, which have 7.5° increments. The RDS (Rotating Dynamic Sensor) offers 2.5° increments and gives us increased flexibility, and allows us probe features that previously we were not able to inspect," says LaBrecque.

As far as the software is concerned, there are several reasons why LaBrecque likes Calypso. But the most important one is its ease of use. "I've been involved with CMMs for the past 27 years," La- Brecque states, "and this software has to be the most user-friendly that I've experienced. This is important to us, because at our company we don't have programmers to write code. We have layout inspectors who know how to inspect parts and the CMM is a tool they use to do their job. With Calypso, you put a part on the CMM, start scanning, and by default you generate a measurement plan. With object-oriented programming, our operators use the features of the design drawing. It is possible to make corrections and changes to existing measuring programs, as well as generate partial measuring runs from an entire CNC program. It has been very successful with our workforce, which was contingent to our success."

Pratt and Whitney now uses 30 CMMs to inspect the wide range of parts they manufacture. They operate in four shifts, including weekends. 1,200 parts are filtered through the quality area within a month's period. "Sometimes we inspect multiple parts, such as a series of bearing housings, for example. They require 100% verification, something that can really bog down our process. So, the CMMs are a definite advantage.

In addition, we were also able to expand our measuring capabilities to the production floor. In the past, our quality assurance group primarily used the CMMs," says LaBrecque.

"The equipment we now have is reliable, but most importantly, our customers are happy. We showed them the actual data that we collected during the study, which included both the results prior to using Calypso and the improvements with Calypso. We proved that scanning technology is allowing us to improve the accuracy and repeatability on our measuring devices and, above all, provide them with consistent and reliable data," he explains.

BENEFITS OF STANDARDIZING

Because of the success they experienced with Calypso, LaBrecque is recommending an upgrade to every CMM at the Pratt and Whitney facility, including all non-ZEISS CMMs. "The trend today is toward standardizing technology and software. The benefits of using common architecture include not only data consistency and reduced cost, but also flexibility and interoperatability. With the standardization of our 13 ZEISS CMMs, we are starting to see these benefits. The partnership with Carl Zeiss has helped us to remain competitive and accomplish our goal of improving product quality and customer satisfaction."