Optical 2D inspection is faster than laser

An optical, non-contact measuring machine can measure and compare flat components up to 1350mm x 900mm with the original CAD file much more quickly than using a traditional laser system.

Whitwam Precision Components an aluminium alloy routing subcontractor, has installed an optical, non-contact measuring machine.

It can inspect flat components up to 1350mm x 900mm and compare results with an original CAD file much more quickly than by using a traditional laser system.

The Planar P120.50 inspection machine was supplied in January 2008 by Press and Shear Machinery, UK agent for the Irish manufacturer, InspecVision.

Chris Whitwam owns and runs the aerospace subcontract firm in Colne, Lancashire.

Before establishing the business in 2004, he was for many years the technical director of machine tool builder Wadkin, and he was responsible for designing and building high-speed routing machines.

Whitwam's long experience in the sector had brought him to the conclusion that there was only one viable solution for inspecting 2D components.

The laser scanning of a profile in two planes works well enough, said Whitwam, but is time consuming.

It is also sensitive to swarf and scratches on the glass table, which the laser often sees as part of the profile.

The Planar P120.50 system gave a superior performance to the laser system.

"The InspecVision measuring process is between two and three times faster than the laser system, irrespective of component complexity," said Whitwam.

"Results are just as accurate and are unaffected by foreign matter on the table".

Whitwam added that the digital camera-based Planar P120.50 system costs less than two-thirds the price of a laser scanner.

An added bonus is that the Planar machine is also able to inspect 3D parts using a line laser measuring option, which Whitwam added to his machine's specification at the time of order.

* Reverse engineering - in addition to inspecting aerospace components that Whitwam produces, the Planar is available for reverse engineering parts for which drawings or electronic data are no longer available.

CAD files can be created for a customer, from which further parts can be made.

This service is being actively marketed, both within the aerospace industry and in other sectors as well.

The Colne company works mainly for a tier 1 suppliers to commercial aircraft manufacturers in Europe and the USA, notably Airbus, Boeing, Hawker Siddeley and Embraer.

The tier 1s supply to Whitwam the CAD files from which cutter paths are created for three high-speed (24,000 rev/min spindle and 3m/min profiling feedrate) routers on the Colne site.

Measured results from the Planar machine are obtained in about 15s and correlated back to the original CAD file already loaded into the machine's control.

Graphically on screen, the measured profile is displayed against a trace of the CAD model, with any out-of-tolerance areas shown in red.

Results may be printed out as required and supplied with the parts to the customer.

Until 2007, the tier 1s that Whitwam supplied were happy to inspect components on arrival, or provide a calibrated master so that the subcontractor could inspect parts by eye.

The latter, although satisfactory, was not ideal as there was a risk of human error, which could lead to a batch of parts being scrapped.

Around of the middle of 2007, Whitwam won a contract from Generation Metals International to supply aluminium parts for the range of business jets being built in the US by Eclipse Aviation.

Components include empennage parts, wing-to-body fairings, keel beams and sundry items such as supports for the pilot's sun visor.

The contract stipulated that all parts had to be inspected and certified before delivery, after having been routed using CNC cutting cycles produced from IGES files originating from Eclipse.

Whitwam's manual methods were not adequate for inspection, necessitating the purchase of a computerised measuring system.

Components are checked on the Planar machine after they have been routed and the tags securing the nested parts to the skeleton have been removed by hand.

The largest router at Colne accepts sheet up to 4m by 1.5m, sufficient to machine the tail fin of a Hawker Siddeley 125 in one operation.

Sheet size generally used is 3660mm by 1220mm and gauge ranges from 0.4mm to 3.5mm.

Parts are nested automatically using software within Whitwam's AlphaCam CADCAM system.

Some cycles take up to 4h if the sheet contains a lot of small, complex shapes.

Many components are subsequently formed, painted and incorporated into sub-assemblies, operations that Whitwam's customers often undertake, although the subcontractor offers the same services through partner companies.

Expected to more than double within the next two years, the Eclipse contract now accounts for a large part of the Colne factory's output.

To cope with increasing demand, Whitwam will be purchasing another CNC router and adding a night shift to supplement the current 6.00 am to 6.00 pm working.

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