Trescal is a global specialist in calibration and measurement services for the industry. Metrology services include calibration, maintenance and repair of test and measurement equipment, inventory management software solutions. In 2012 Trescal was present in 16 countries, with a 157 million euro turnover business consisting of 62 calibration laboratories, 90 customer satellite facilities, 1,500 employees and 25,000 customers. In the UK, Trescal has the most extensive UKAS accredited technical capability and employs 360 people, of which 250 are qualified engineers and technicians across a wide range of instrumentation and measurement disciplines.
Accuracy and stability of the instruments are extremely important
The majority of calibration activities performed by Trescal for their aerospace customers are related to thermal processing equipment used for heat treatment of aerospace metal components. The most pertinent specification for such calibration work is provided by the Aerospace Metal Specification AMS2750, frequently audited by National Aerospace and Defense Contractors Accreditation Program (NADCAP), which covers the pyrometric requirements for thermal processing equipment used for heat treatment; specifically, temperature sensors, instrumentation, thermal processing equipment, system accuracy tests (SAT) and temperature uniformity surveys (TUS). Within AMS2750, there are regulations controlling the calibration accuracy of measurement instruments for various applications.
Usually aerospace component heat treatment furnaces are equipped with thermocouples, temperature control systems and temperature recording equipment each of which complies with regulations in AMS2750. These furnaces are regularly checked for temperature uniformity by the temperature control systems and the temperature control systems are, in turn, frequently checked for accuracy. These SATs are a critical check on system accuracy, typically performed weekly to identify early signs of system accuracy changes or drift. The accuracy and stability of the instruments used for the SAT are extremely important, as errors can lead to variations in aircraft component product quality, which in turn could lead to production downtime, product quarantine, or even the grounding of aircraft. As Neil says, “Getting these SATs wrong is not an option”.
The accuracy and stability of the instruments used are extremely important, as errors can lead to variations in aircraft component product quality which in turn could lead to production downtime, product quarantine, or even the grounding of aircraft.Neil Hoskins, Deputy Calibration Manager at Trescal’s facility
No surprises wanted, reliable history trend analyses are crucial
For many companies manufacturing components such as fan blades, fan casings, fuel systems, landing gear and many others, the critical weekly SAT checks are completed by Trescal using the Beamex MC2 TE temperature and electrical calibrator and the Beamex MC2 MF multifunction calibrator with added pressure measurement capability for performing pressure calibration of pressure gauges and transmitters. Trescal uses the Beamex MC5 and the MC6 calibrator to calibrate the furnace temperature control system elements and data recording devices every 3 months.
Neil constantly reviews the test equipment used for TUS, SAT and instrument calibration to make sure it is accurate enough, and, equally important, stable enough. Each individual calibrator’s calibration history is recorded and analysed to ensure that the calibrator is within the specification limits and will remain within the specification limits with a high degree of confidence until the next SAT or calibration event. Neil says, “We record at least 5 calibration events, and sometimes up to 2 years of data, before we can be sure that a calibrator can be considered stable and fit for the purpose. This calibration history is more valuable to us than the monetary value of the test equipment”.
Over the years, Neil has acquired significant calibrator accuracy information which has proven that the MC2 and the MC5 are fit for Trescal’s purposes and adhere to its requirement to meet AMS2750. More recently, the MC6 calibrator has also passed the stringent tests of both Neil and Trescal. Particular attention is paid to the accuracy of the calibrator’s internal reference junction. Neil comments, “The accuracy of the reference junction in the MC2, the MC5 and the MC6 across the working range of the calibrator is excellent”. Neil’s considerable data on the MC2, the MC5 and the MC6, coupled with the excellent feedback his field-based technicians provide on the robustness and reliability of the Beamex calibrators, have meant that the MC2, the MC5 and now the MC6 are placed on the Trescal Approved Product List (APL) and remain Neil’s preferred choice for calibration.
Neil’s confidence in the Beamex calibrator range has led to his recommendation of Beamex products for similar use at a number of different Trescal facilities around the world. He also recommends Beamex products to many of Trescal’s customers. When asked for a response on what the Beamex experience means to Neil, and Trescal, he replies, “As Deputy Manager of a calibration facility, what I want in a calibrator is something that gives me no surprises, an instrument that does what it is supposed to do and can be relied on in complete confidence to deliver accuracy, functionality and ease of use time after time”.