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Applying sensors in harsh environments
672 0 Dec 09.2013, 17:44:00

In January, PCB Piezotronics, a well-known manufacturer of sensors, formed a new Aerospace & Defense division, following closely upon the creation of the company's Automotive Division. The company tapped Ron Livecchi to head up the Aerospace & Defense Division as its senior director. A 30-year veteran of the aerospace industry, Livecchi was most recently VP and GM for Mokon. He also has held leadership roles at Jabil Circuit, Parker Hannifin Aerospace, Moog, and Lord Corp.

Iin this exclusive interview, Livecchi explained why the division was created and also expanded upon the challenge of deploying sensors in the harsh environments of aerospace and defense applications.

Q: Did business growth and customer demand for sensors mandate the formation of the new division?

A: For the past 41 years, PCB Piezotronics has been providing piezoelectric sensors to the aerospace and defense industry, though not in a fully dedicated fashion. Within the past few years, the company has experienced unprecedented prosperity in this market, which led to a decision to develop a new group uniquely tailored to the highly specialized needs of aerospace- and defense-related customers.

The division specializes in products and programs developed exclusively for the global aerospace, civil and military aviation, defense, homeland security, nuclear, and test and measurement markets.

Q: How do harsh environments challenge mounting, testing, and data capture from sensors?

A: Harsh environments are major considerations for test engineers, who need to ensure the right sensors are employed to make reliable, repeatable, and accurate measurements. The possibility of contamination, for example, can usually be prevented by good sensor design—with hermetically sealed sensor housings—and appropriate selection of cables and connectors. Manufacturers also routinely certify sensors and instrumentation to DO-160 and MIL-STD-810, as well as other proprietary customer standards, to ensure the product can exceed requirements for the application.

For some harsh environments, the challenge is to be able to mount and position a sensor where we need it. For example, under heavy vibration, an improperly mounted sensor can break loose during a test. Proper strain relief is a factor, as is designing cables to meet requirements of a particular measurement environment, such as using hard-line cables instead of standard cabling. To avoid the pitfalls of improper sensor usage in a given testing environment, an engineer must fully understand the conditions and demands of the testing environment.

Both high and low temperature extremes are important considerations. We have specially designed high-temperature sensors to reliably perform at temperatures of up to +650°C. We also have cryogenic sensors designed to withstand extremely low temperatures, down to –300°C. In addition, we offer space-rated products, which provide immunity from radiation and outgassing. One of the benefits of our full in-house manufacturing and testing resources is the added flexibility to modify our standard products or packaging to meet even the most challenging of application requirements.

For example, our team recently worked with NASA on a super low noise floor (–40 dB measured) ultra-low frequency, low-amplitude microphone for measurement of Space Shuttle noise during a launch at Cape Kennedy, FL, with an array located at a facility in Langley, VA. The microphone, with a 3-inch diameter, is able to pick up noise from distances of several states away. It may be the quietest microphone ever built.

Q: How would you advise customers in aerospace and defense applications regarding testing costs vs. high reliability?

A: For an aerospace and defense customer to ensure high reliability, it is best to take a proactive approach, starting with a robust sensor design and, in particular, one designed according to six-sigma business processes. We recommend a customer start with a sensor design more robust than the application, versus testing a sensor with the objective of confirming whether a design will be robust enough. It is also important for a manufacturer to understand its core competencies well, so as to ensure that what is offered to a customer is robust.

In aerospace, the cost of testing is so high that it is a false economy to try to cheapen a sensor product and sacrifice the critical reliability of measurements. This is something we understand well, and we pride ourselves on offering a high-quality and cost-competitive product along with the value-added benefits of our in-house manufacturing, testing, and engineering resources and 24-hour technical service and support.

Q: Is six sigma an assumed requirement for aerospace and defense division customers?

A: Any company with a vested interest in six-sigma business processes typically ensures its vendors are also operating according to six-sigma business processes, as the quality of a finished sensor is only as good as the quality of component parts. Our company has the added benefit of full in-house manufacturing, and most all of our related sensor components are made right at our corporate headquarters, which allows us to ensure the same uniform standards and practices across all aspects of the business process. This allows us to have greater control over quality, delivery, and cost.

That noted, it is not necessarily a customer requirement on the aerospace and defense side, and more of an internally driven commitment to continuous quality improvement. Six-sigma practices have become an integral part of our business processes, as well as throughout our entire organization.

There are two key elements of this activity. The first element is ongoing education and development of six-sigma processes and lean manufacturing skills. Thus, we continually add six-sigma black belts to our organization. This leads to the success of the second element, which is the maturing of our design and production process, resulting in greater yield rates, lower production costs, and shorter lead times—all of which ultimately benefit our customers.

Q: What other types of business process qualifications and accreditations are in place at PCB to address the aerospace and defense industry’s needs?

A: We have adopted several registrations pertinent to operating within the aerospace and defense industry. Our business systems are ISO 9001:2000 certified. To reinforce a commitment to aerospace and defense customers, we are AS9100:2004 certified. Our calibration services are American Association for Laboratory Accreditation (A2LA) accredited to ISO17025, which tells our customers that we are dedicated to quality in all aspects of the process—from paperwork, through design and development, and to shipment of the finished product. A2LA-accredited calibration is a detail that helps ensure measurement accuracy, and one which illustrates the attention to detail which customers can expect when purchasing from us.

Part of our commitment to customers in the aerospace and defense industry is the monitoring of quality and business process requirements. We work to earn any additional accreditations which may be required to best suit the needs of customers.

Q: What are some typical test considerations for homeland security? nuclear? health and usage monitoring systems (HUMS)?

A: Homeland security applications have not been traditionally covered by this company’s product technologies, as the types of monitoring applications are brand new, and sensor and instrumentation requirements not clearly defined. In the HUMS market, we have a 20-year history of providing predictive maintenance and smart sensors, which have served as segue to industrial HUMS and prognostics.

Overall application of our piezoelectric sensors into HUMS for helicopters, unmanned aerial vehicles (UAVs), and fixed wing aircraft, are widely gaining acceptance as an effective predictive-maintenance strategy. Due to the large number of critical flight safety systems on aircraft, particularly rotating systems on aircraft and helicopters, vibration monitoring technology is effective in detecting and thus preventing catastrophic mechanical failures.

We offer a full line of HUMS sensors and associated signal conditioning, which has specialized requirements for performance, durability, and packaging, depending on the requirements of the aircraft. For the nuclear industry, we offer a series of high-temperature radiation hardened sensors. For cooling tower monitoring, PCB has introduced a series of industrial smart vibration switches, which are low-cost integrated alternatives to traditional vibration monitoring technology.

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