Five-axis machining eliminates relocation errors

A machine shop finds that the five-axis approach allows complex profiles to be completed in two operations rather than the five or more settings required on a three-axis machine.

Although founded as a demonstration facility for market-leading CAD/CAM software, ISO 9001-accredited Delcam UK Tooling Services is very much a business unit in its own right.

Having begun with what Brian Hawkshaw, director, describes as: "Some rather rudimentary machine tools", this division of Delcam, located on Birmingham's Small Heath Business Park, UK, is now equipped with the latest manufacturing technology.

It has extended its remit to the machining of workpieces ranging from small moulds and dies to aircraft undercarriage components.

The installation of a Mazak Variaxis 630-5X machining centre signalled a step change in that it provided Delcam UK Tooling Services for the first time with a five-axis simultaneously controlled machining capability.

"This investment was prompted by potential orders for aerospace components in what we regard as high volume quantities," says Hawkshaw.

"A five-axis approach allows complex profiles to be completed in two operations rather than the five or more settings required on a three-axis machine".

"By effectively reducing to zero possible errors due to relocating the workpiece, it safeguards high value added components destined for the aerospace, automotive, defence and nuclear industries".

"These account for many hours of valuable machining time, although the time delay that would result from scrapping one of these complex components is arguably of even greater significance." Although it continues to offer prospective software customers the opportunity to evaluate PowerSHAPE and PowerMILL software, Delcam UK Tooling Services is home to a highly skilled team of engineers delivering a diverse range of services from product modelling, NC programs and manufacturing through to final inspection and certification.

However, the emphasis on high value manufacturing activities, coupled with the requirement to 'field test' the latest software developments and to assist software users, ensures that every investment proposal is subjected to searching scrutiny.

"We began this particular selection process by shortlisting six possible suppliers and concluded with the machining of a test piece designed to push the Mazak to the limit of its five-axis capability," says Hawkshaw".

""This was in terms of surface finish, including blending of radial and angular surfaces; accuracy, checked against the original CAD model; and cycle time, as a measure of the response to complex configurations and rotations".

"Assessed against these criteria, the Mazak easily met and indeed exceeded the criteria for selection." The Variaxis 630-5X, which has axis travels of 630mm (X), 765mm (Y) and 510mm (Z) and a maximum traverse rate of 50m/min, is capable of taking components weighing up to 500kg.

Featuring an optional 30kW, 25,000 rev/min spindle, it is equipped with a table capable of tilting up to 150 deg (A axis) and rotating to +/-360 deg (C axis).

Linear scale feedback from each of the five axes was a specific requirement, but Brian Hawkshaw soon became aware that the Mazatrol Fusion CNC system had more to offer than precise positioning." Hawkshaw said: "There are a large number of parameters that can be adjusted within the control to give certain enhancements.

For example, when carrying out a roughing operation we are able to 'desensitise' certain parameters so that the machine will run faster.

We can then reverse this sequence for a finishing cut to guarantee a high quality surface finish while benefiting overall from further optimising the cycle time," said Hawkshaw.

The Variaxis 630-5X is regarded by the skilled toolmakers who operate it as 'a strong, rigid machine that does what it says on the box'.

This assessment is endorsed by Hawkshaw, who says: "We are delighted with the Variaxis' performance and, in combination with the latest versions of our PowerMILL software, we are producing machining programs that combine efficient metal removal with high accuracy and excellent surface finish.".

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