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The Crysta Apex S7106 CMM.
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The Contracer CV-4500H4 contour measuring system.
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The Euro-C-A7106 CMM.
Impcross is a UK-based subcontract manufacturer of precision engineered components and parts for the aerospace industry. The company employs more than 100 staff at a 5,100 m2 facility in Stroud, Gloucestershire, and counts amongst its clients the OEMs BAE Systems, GE, Honeywell, Messier Dowty, Safran, UTC, NSK and Rolls-Royce.
Impcross invests heavily in equipment from reputable brands such as Delapena, Hitachi, Schaublin, Seiki, Studer, Matsuura and Mazak. One brand that the company has come to rely on since its establishment in 1994 is Mitutoyo, a Japan-based manufacturer of metrology equipment.
Historically, Impcross’ workflow has been 75 percent prototype and one-off small-batch runs, with the remainder being long-run work. However, the appointment of a new CEO, a strategic re-alignment and further investment has seen the company realise its aims of reversing the proportions of this mix to become 75 percent production oriented while solely targeting the aerospace OEM sector (since it had previously also served the military, motorsport and petrochemical industries). This strategy is obviously paying dividends as staff levels have almost doubled in five years.
To attain and develop long-term partnerships with aerospace OEMs, Impcross has achieved a number of accreditations, including:
- ISO:9001 Quality management;
- National Aerospace Defence Contractors Accreditation Programme (NADCAP) Chemical processing (CP) and Non-destructive testing (NDT); and
- AS9100 Revision D Quality management system requirements for aviation, space and defence organisations.
According to Steve Arnold, operations director at Impcross, these accreditations are underpinned by a long list of Mitutoyo metrology equipment and quality management systems. “Not only has Impcross worked with Mitutoyo since its inception, but my father and the company’s founder Richard Arnold previously owned another business and has worked with Mitutoyo since the 1960s,” he said. “Mitutoyo has always served us with distinction, always had the technology to efficiently meet our needs and, as the industry and technology has evolved, always been at our side.”
The Mitutoyo equipment inventory
Impcross has had two coordinate measuring machines (CMMs), the BHN706 and Euro-C-A7106, at its facility for 18 and 24 years, respectively. Regular software updates as well as calibration and maintenance programs mean that these CMMs are still used daily. The company is expecting delivery of a third CMM, the Crysta Apex S7106, to help alleviate capacity issues and accommodate ongoing growth.
As well as CMMs, Impcross also has LH-600 linear height gauge 2D measurement systems, PJ300 profile projectors, digital bore gauges, Surftest SJ-401 portable surface roughness testers, a Surftest 211 surface roughness tester, a Contracer CV-4500H4 contour measuring system, a Roundtest RA2200AH roundness/cylindricity measurement system and laser scan micrometers.
Impcross manufactures and first-off inspects more than 500 different component types for its customers every month. To manufacture such a large variation of complex large-batch components, the company runs its machine shop and metrology department 24/5, with full traceability on its production and quality procedures.
Demonstrating the importance of Mitutoyo equipment
Two years ago, Impcross won a contract to manufacture reverse-thrust valve housings for an aerospace OEM serving the defence industry. These housings are manufactured from an aluminium alloy for lightness. A critical feature on the housings is a thread that connects to a hose that works at a pressure of 5,000 psi.
To make it possible to produce a light alloy part capable of withstanding such high pressure, the OEM had collaborated with its tooling supplier on the design of a unique thread geometry prior to awarding the contract to Impcross. The customer stressed the importance of highly accurate inspection of this thread form as it was tied to a tolerance of less than 50 μm.
Commenting on the contract, Arnold said: “We work in partnership with our clients and this particular OEM customer even supplied a Mitutoyo Contracer CV-4500 to guarantee high-quality inspection of the unique thread form specified. From a conformity perspective, our Mitutoyo metrology equipment provides comprehensive reporting, and many of our OEM partners also use Mitutoyo equipment, so they are very familiar with the format, quality, consistency and reliability of the Mitutoyo reporting system. This particular housing is a critical aircraft component and the Contracer CV-4500 is responsible for checking every part.”
Another critical component manufactured by Impcross is a valve sleeve guide that works in conjunction with the reverse-thrust valve housing. The stainless-steel sleeve guide has a cylindricity and parallelism tolerance on the bore of 1.2 μm over its 127.7 mm length, with a surface finish tolerance of 0.006 to 0.008 mm or 2 μm. Machining a sleeve guide with a bore tolerance of 1.2 μm and a surface finish of 2 μm is a difficult task, compounded by externally turned features that are all tied to a tolerance of 5 μm.
Impcross manufactures more than 200 sleeve guides every month. According to Matt Coopey, quality inspector at Impcross, inspecting these parts would be impossible without the Mitutoyo Roundtest RA2200. “The sleeve guides are extremely challenging parts and the Roundtest RA2200 is the best product in the market for measuring them,” he said. “It enables us to produce hundreds of parts each month and inspect 100 percent of parts.”
Mitutoyo delivers inspection efficiency
Methodologies such as statistical process control (SPC), process capability (Cpk), lean manufacturing and kaizen (continuous improvement) enable Impcross’ quality assurance department to be as efficient as the shop-floor.
Arnold explained: “All our metrology equipment utilises the latest software updates from Mitutoyo and there is complete conformity between our equipment, processes and reporting. Furthermore, we have the MCOSMOS CAT 1000 software integrated into our Mitutoyo metrology equipment. This means we can download the CAD/CAM files for components from our servers directly to the Mitutoyo machines. In the case of the CMMs, we can download the model directly from our CAM software and set the datums on the CMMs according to our models. This integration is critical for the productivity of our metrology department.”
Impcross recently secured a high-volume order for a family of gyroscope components in batches of 50,000, again for the defence industry. To process the parts, the company’s three CMMs will use a grid fixture plate and apply SPC to record data for the customer. All of the company’s CMMs, including the one on order, will run 24 hours a day and check more than 50 parts an hour.
Arnold concluded: “As a business, we have written our own quality software, designed failure out of processes so we can quote with intelligence, and we risk-analyse and manage every process. As a business that captures data at every level, the Mitutoyo equipment has been integral to our success. Mitutoyo has been such a reliable, consistent and high-quality supplier for so many years that we take their service and support levels for granted. What is equally important is that our aerospace OEM clients are filled with confidence as soon as they know we have a QA department filled with Mitutoyo equipment.”
Impcross
Mitutoyo