LK develops 5-axis CMM for complex parts

2 mins read

Built in the UK by LK Metrology, the latest Altera range of CMMs has been coupled with Renishaw's REVO-2 scanning system and multi-sensor technology to offer manufacturers a 5-axis solution for inspecting the dimensional accuracy and surface finish of components. A notable design feature of the newly developed SCANtek 5 package is the ceramic construction of the CMM beam and spindle, which combines optimal stiffness-to-weight ratio for responsiveness with mechanical and thermal stability.

Said to offer unprecedented measuring speed, the SCANtek 5 multi-sensor package includes Renishaw's MODUS software for importing data, controlling the CMM, acquiring results and reporting – including GD&T labelling. The machine's high scanning speed boosts measurement throughput, shortens production lead-times, provides awareness of product conformance, and prevents the metrology department from becoming a bottleneck.

SCANtek 5 is available in a variety of standard measuring volumes from 800 by 700 by 600 mm (8.7.6) to 6,000 by 2,000 by 1,000 mm (60.20.10), with larger options. The Alteram models with repeatability from 1.5 micron are being marketed alongside an Altera SL range offering repeatability from 0.7 micron. LK says it is so sure of the long-term performance of these premium machines that it is the only CMM manufacturer to offer a 10-year accuracy guarantee.

Ready for operation immediately it arrives in the inspection room or on the shop floor, the 5-axis CMM gives users a competitive advantage, making it easier to win new work and speed product development. A 3-axis measuring solution, by contrast, is often unable to measure some complex features. In any case, such a machine requires constant acceleration and deceleration of large moving elements, whereas the rotations of the REVO-2 head are synchronised with constant velocity machine motions when scanning, allowing changes in component geometry to be followed without introducing dynamic errors.

Scanning at up to 500 mm/s, without the stylus leaving the surface of the component, allows the co-ordinates of up to 4,000 points to be captured 'on-the-fly' every second, a rate of data acquisition far higher than is possible using conventional probing techniques. There also exists the potential to include rapid, single-touch routines in a measuring cycle. Moreover, the flexibility offered by infinite head positioning increases the effective measuring volume by minimising the need for head reorientations, while allowing complex measuring. Exchanging the REVO-2 scanning probe for one of the vision modules increases data collection rates further, and the results can be correlated with those acquired using tactile methods.

By employing different tip arrangements and knuckle joints, surface finish analyses can be combined with other CMM measurements in a single operation, the basic output being Ra, RMS and raw data, with a range of additions provided by standard and advanced surface-texture options. Even fine bores down to 5 mm in diameter can be inspected. Various change racks up to 1 m in length are available for housing sensors, probes and styli, to enable automatic exchange during a measuring sequence.

The MODUS software, with its user-configurable interface, provides a platform for the creation of programs, either by teach mode or from a CAD model imported via the usual graphical exchange formats, or directly from CATIA, Siemens NX, Parasolid, PTC Creo or SolidWorks. Wizards in the Windows programming environment employing conversational, graphical and drag-and-drop methodologies give access to a range of macros and standard scanning routines, such as helical, circular and sweep, to ensure best-practice metrology without the need for specialist programming skills. The native DMIS program, with drawing geometry, dimensions and tolerance data embedded, can be simulated offline to check for potential collisions before the inspection cycle is run on the SCANtek 5.

A wealth of textual and graphical reporting functionality is offered, including multi-part inspection for series production and real-time reporting during program execution. Data exchange to third party applications such as Excel, XML or SQL is provided, as well as to Q-DAS for statistical process control.

A SCANtek 5 is available in LK's Castle Donington technology centre for customer demonstrations. Two recently completed tests involved comparisons between the 5-axis and 3-axis scanning of a cylinder head and an aero engine blisk. In the former automotive application, 12 valve seats and guides were inspected in 3 minutes 42 seconds, instead of 29 minutes 13 seconds, an increase in throughput of nearly seven times. In the case of the blisk comprising 29 blades, nine sectional, eight longitudinal and two root profile scans per blade were completed, plus one annulus profile scan, in a total of 2 hours 10 minutes, compared with 22 hours 11 minutes using 3-axis scanning – a 922% productivity improvement.