CMM has CAD interface upgrade for aerospace work
Keywords: Aerospace industry, Standards, Upgrades
In 1998, Leicestershire subcontractor, Castillion, purchased from Shin Nippon Koki (SNK) a 6 m x 2.5 m x 1 m capacity co-ordinate measuring machine (CMM). To make it fully compliant with standards in the aerospace industry, a sector which Castillion serves exclusively, software and control equipment from LK was added before the machine was commissioned (Plate 1).
Forming part of an £6 million turnkey package which included five SNK machining centres, the specialised CMM is easily able to measure wing spars in excess of 5 ft across as used in the larger airliners, as well as bulky components such as the centre box section for a Nimrod.
Such a facility had to meet one criterion in particular that is now virtually an aerospace industry standard throughout Europe, namely that the CMM should use the "DMIS" programming language. Indeed, it is mandatory for some contracts like the supply of components for the Eurofighter Typhoon. Unlike many programming systems which are proprietary and run only on the vendor's own machines, DMIS is stated to be an open language that allows any compatible CMM to read the programs.
The standard SNK machine did not conform so the Japanese manufacturer approached LK to supply the appropriate software and controller equipment. The British company, itself a CMM manufacturer, was in the vanguard of the development and adoption of DMIS during the mid 1990s. LK interfaced with the drives on the SNK CMM and installed its DMIS programming system, but the project went further than this.
The LK package included the supply of CAMIO, a CAD-to-CMM interface which allows solid models created in such CAD systems as CATIA – widely used in the aerospace industry – or alternatively IGES files to be imported and used as the basis for writing the measuring programs. This too is important for Castillion as the industry is moving away from the supply of drawings.
Said quality manager, Andy Watson, "When a new job comes in these days, 80 per cent of the time it is in electronic format. All the latest Airbus, Nimrod and Westland work, for example, is received in this form.
"The same CAD information that is used via our NCL CAM system and post processing to drive our 5-axis machining centres is copied into CAMIO. Using an off- line terminal, the measuring routine is programmed so that it is ready to inspect the part as soon as it has been machined.
Concurrently working on the CAD data in this way shortens our turnround from order to delivery."
Only on receipt of a hard copy drawing is the on-line LK terminal used in teach/learn mode with the machined part on the CMM table (unless the job is very simple in which case it is programmed manually from the drawing). Whilst this sequential route is effective, the benefits are lost of parallel working in the machining and metrology departments.
Programming time, even with computer assistance, can take anything up to one week, depending on the complexity of the part. Sometimes as many as 4,000 features need to be checked and the inspection cycle can take up to five hours."it is very easy to make mistakes if one is doing this by hand ", commented Andy Watson, "to the extent that we would not really be able to handle some of the work we do now without LK CAMIO".
Plate 1 Castillion frequently mounts components on edge to facilitate one hit inspection. Here a Rib 9 joint strap (still in its manufacturing window frame) for the A 300/600 Series Airbus is being checked on the SNK CMM using LK's CAMIO software
Other functionality useful to Castillion within the LK software includes"Launchpad", an operator interface which manages inspection programs and holds photographic images of components for easy identification. For each job, a graphical menu structure is presented detailing how to position the component and instigate the program. LK CAMIO reporting is a further benefit claimed,enabling comprehensive documentation on the inspection to be presented to the customer.
The SNK CMM at Castillion currently works a single shift, seven days a week,although utilisation is likely to stretch into a night shift later this year as production output increases. Average batch size is 6-off, usually hand and opposite, and inspection starts at 100 per cent, reducing according to application and customer to a minimum of one per batch.
Castillion is part of the Prematec Corporation and an SNK CMM of similar capacity is currently being installed at another Prematec factory in Lianstrisant, South Wales, again as part of a turnkey package including the Japanese manufacturer's machining centres. This time, however, the LK controller and CAMIO software have already been fitted following an agreement reached in 1999 with SNK whereby all the company's new machines would be thus equipped by LK. As a result of the agreement, several SNK CMMs have been already been configured in this way and delivered to customers in Europe and Japan.
Details available from: LK Limited, Tel: +44 (0)1332 811349; Fax: +44 ()01332 850149; E-mail: sales@lk-cmm.co.uk;Web site: www.1k-cmm.com
