Shop-floor inspection of complex aerospace components directly from C.A.D.

Citation

(2003), "Shop-floor inspection of complex aerospace components directly from C.A.D.", Aircraft Engineering and Aerospace Technology, Vol. 75 No. 2. https://doi.org/10.1108/aeat.2003.12775bab.003

Shop-floor inspection of complex aerospace components directly from C.A.D.

Shop-floor inspection of complex aerospace components directly from C.A.D.

Keywords: Aerospace, Components, Software

The proven capability of LK's G-90C coordinate measuring machines (CMMS) and its powerful programming software, CAMIO, were central to the selection of this manufacturer's equipment by Bolton-based aerospace contract machinist, Silcoms Ltd, for high precision inspection of aero engine components. Two LK machines with measuring envelopes of 2 m × 1 m × 1 m, and 1 m × 1 m × 800 mm, have been installed in a move that has provided a major upgrading of inspection facilities at the company (Plate 1).

The main stimulus for the investment has been Silcoms' involvement as a supplier of complex ring-type components for turbofan jet engines, among them the front pivot ring for a well known aircraft engine manufacturer. The ring is, in fact, a high precision assembly of two annular aluminium forgings that are machined both separately and in the assembled state.

Plate 1 An aero engine pivot ring being inspected on one of the LK G-90C CMMs at contract machinist, Silcoms, Bolton

Bill Worswick, Engineering Manager at Silcoms, has been closely involved with the project from its inception. He explained, "We developed a dedicated machining cell for these components comprising a pair of large vertical borers and a pair of five-axis machining centres. The components measure from 1,000 mm to 1,500 mm in diameter and are machined with an overall tolerance of 50 microns, although tighter tolerances are required on certain features. The two-piece pivot rings, for instance, have a complex tapered joint which requires extremely accurate location."

The combination of component size, complexity and accuracy meant that inspection requirements were beyond the capability of Silcoms' existing CMMS. Ease of use and speed were also an issue as the company wanted inspection to be carried out by personnel operating the machine tools with a view to keeping production flowing.

"I was also keen that the measuring machines should be capable of being programmed off-line", Bill added. "Especially in the early prove-out stage of a new component, the ability to have the CMM program available before the first-off has been machined saves a lot of time. Silcoms has invested in solid modelling CAD and off-line programming for our machine tools, so adopting the same approach with the CMMs was the obvious way to go."

The process of identifying the right CMM for the job began in January 2000, well ahead of the projected delivery date for the first front pivot rings in March 2001. Bill sought proposals from several potential suppliers but ran up against a number of problems with most. He recalled, "in some cases the supplier could offer an off-line programming solution but was using third party software to do it. Other vendors tried to persuade us that we did not actually need to program off-line. At the time that we were looking, only LK was able to offer a complete, single-source package and, moreover, demonstrate it in action in an environment and application similar to our own."

Having settled on the G-90C, Silcoms specified the machines for delivery in July. Apart from the work envelope, both machines are identically specified and, subject to component size, able to run the same programs. In practice this gives interchangeability of around 85 percent.

Both machines are sited in shop floor areas, the larger machine being in the same section as Silcoms' jig boring facilities. This is conveniently adjacent to the ring machining cell, facilitating rapid inspection straight off the machine tool by the operators.

Initial installation by LK was rated as "very good". Subsequent resiting of the smaller machine was accomplished in 2 days. As installed, the machines feature a Rensihaw PH 10 motorised probe with high accuracy TP200 probing. Software includes both CAMIO CAD Interfacing software and the LaunchPad menu system, which allows programs to be run simply by selecting pictures of the components on the computer screen. The user is then guided through the set-up of the component on the machine before measuring starts.

To meet component delivery schedules, Silcoms commissioned LK to develop the measuring program for the pivot ring. This comprises a two-piece assembly with an angled, tapered outerface into which a number of complicated pockets are machined. Machining of the component is a lengthy process necessitating up to four visits to the CMM. A further eleven components are machined in the cell.

Bill explained, "A full audit check can take up to 1h on one of the larger rings, which is a massive saving on our previous inspection system. However, having established process capability, we have been able to be selective and concentrate on those features that show variance in day-to-day checking. All of the measurement information is archived and can be referenced back to the component, while CMM programs are stored on a central server."

He continued, "The off-line programming system works well. CAMIO integrates fully with our SolidEdge CAD system and the process gives us full traceability of program data. So far we have developed over 200 programs for use on the LK machines."

Measurement using the G-90Cs is significantly faster than with the facilities previously available to Silcoms. The LK machines are better equipped for the higher accuracy and complexity requirements of the new components, allowing full inspection on the shop floor. This has enabled the company to meet production and quality targets on the front pivot ring project.

Bill concluded, "The larger LK machine is integral to our production process within the cell; we would be unable to meet our obligations without it. In practice it has fulfilled all of our requirements. The LaunchPad system in particular makes the measurement function easily accessible to non-inspection personnel while, CAMIO gives us a significant advantage so far as pre-preparation of the measuring program is concerned."

For further details contact: LK Limited. Tel: +44 (0)1332 811349; Fax: +44 (0)1332 850149; E-mail: sales@lkuk.co.uk; Web site: www.lk-cmm.com