Metalcutting productivity increased by simultaneous programming of CMM

Citation

(2007), "Metalcutting productivity increased by simultaneous programming of CMM", Aircraft Engineering and Aerospace Technology, Vol. 79 No. 4. https://doi.org/10.1108/aeat.2007.12779dab.001

Metalcutting productivity increased by simultaneous programming of CMM

Metalcutting productivity increased by simultaneous programming of CMM

On the shop floor of high-precision contract machinists, Verdict Aerospace, Chalfont St Peter, UK, production output from the machine tools is reported to have increased dramatically since a Metris LK co-ordinate measuring machine (CMM), together with the manufacturer's CAMIO programming software, were installed at the end of 2005 (Figures 1 and 2).

The higher productivity results from being able to program inspection cycles directly from CAD models of components, before they have been machined, allowing far higher spindle up-time than when machine tools stood idle waiting for first-off inspection results from manually operated or conventionally programmed CMMs. Verdict, formed in 1951, is the only remaining privately owned Tier 1 supplier to Airbus, whose contracts account for a little less than half of the contract machinist's £5.5 million turnover.

Figure 1 Paul Shields, Quality Engineer at Verdict Aerospace, using the Metris LK Integra CMM to check an aluminium Track 4 secondary, part of the Airbus A380 wing. Surface profile tolerance must be within ±0.1mm

Figure 2 The CAD model of the Airbus A380 Track 4 secondary within the CAMIO environment

Despite the aircraft manufacturer's policy of reducing its supplier base, in 1998 Verdict won a contract to manufacture access door panels for long-range and single-aisle aircraft. More recently, it was awarded four tranches of work for the A380, namely manufacture of flap track diaphragms (18 per aircraft), joint straps (600 per wing), access door panels and a turning package. A380 contracts alone will increase Verdict's turnover by £2.5 million by the end of the decade.

The firm's latest investments in production equipment were prompted by this success. In addition to the Metris LK Integra CMM with its 1.5 x 1.2 x 1m measuring envelope, three high-speed (20,000rpm) Matsuura machining centres have been installed, including a four-axis model with automatic pallet change. The contract machinist has also purchased Catia V5 CAD software.

Said Verdict's engineering manager, Ray Gibbs, “Before our new CMM and the CAMIO off-line programming software were installed, we did not have the ability to prepare an inspection routine in advance of machining the first part”.

“In practice, we would inspect the first-off on a manual CMM, as it was faster than programming our older CMC measuring machine in `learn' mode, which could take up to two days for a complex part. Consequently, for batch runs of components requiring frequent inspection on our old CMM, we saved time by programming it from the first, manually-checked part, concurrently with machining the remainder”.

“Even so, depending on component complexity, the machine tool spindle would be stopped for anything from 3h to a day while manual first-off inspection was in progress; and if there were any errors, the part would have to be measured again, so there was further machine downtime.”

Ray went on to describe the significant advantages of the new metrology process based on the LK Integra. Now, as soon as the CAD model of a part arrives, as a CATIA file in the case of Airbus and many others in the aerospace sector, the data is fed into two computer-aided manufacturing software packages. One produces the cutter paths for the machine tool and the other, LK CAMIO, generates the measuring routine that the part, when manufactured, will undergo on the Integra CMM. The machine tool is therefore idle only for as long as it takes to measure the first-off part, which is done immediately it arrives in the metrology room. Inspection can be as quick as five minutes and is rarely longer than one hour, even for the most intricate parts. Productivity is therefore much higher compared with when first- off inspection took 3-8h.

For second and subsequent parts, the quicker axis movements of the modern Metris LK Integra enable inspection cycles to be completed faster than on the older CMC CMM. So again, machine spindles are stopped for a shorter time when producing batches of parts needing periodic or 100 per cent inspection, boosting productivity further.

A particular benefit claimed of Metris LK CAMIO software is its ability to import native CATIA files directly, without the need for translation. This standard option from Metris, involving some 500 lines of code, allows Verdict to comply with the stipulation by Airbus that parts must be checked against the original CAD model in the form that it was supplied, complete with geometric dimensioning and tolerancing (GD&T) definitions.

The LK CMM has had the additional effect of deskilling inspection to the point where machine tool operators, rather than metrology professionals, are beginning to take responsibility for measuring the components that they produce. To take this a step further, a pictorial front-end called Launchpad is being installed. It identifies the inspection program and necessary fixturing, and instigates the CMC cycle when the operator clicks an on- screen photograph of the part.

Overall, upgrading of metrology capability and engineering software at the Chalfont St Peter factory has had a big impact on Verdict Aerospace, not only in terms of increased productivity, but also in its move towards paperless manufacturing.

In so doing, the contract machinist is mirroring the direction in which its main customer, Airbus, has already gone in order to facilitate closer communication and co-operation with its pan-European suppliers.

Details available from: Metris UK Ltd Tel: +44 1332 811349; Fax: +44 1332 850149; E-mail: sales@metris.com; web site: www.metris.com. Contact: Paul Bexon, Technical Metris Headquarters. Tel: +32 16 74 01 14; Fax: +32 16 74 01 02.