Bridge CMMs

With more than 30 years experience of manufacturing metrology products, ELEY Metrology are proud to be the leading UK independent manufacturer of coordinate measuring machines.

With high precision manufacturing techniques, and constructed from hand lapped granite, ELEY CMMs are the only machines that don’t require software ‘error mapping’.

Available in a range of sizes from 500x400x400 up to 3000x1800x1200mm these CMMs are capable of scanning with the Renishaw SP25 constant contact probing system.

Larger sizes are available on request, and indeed special designs can be produced, such as the groundbreaking LBM (Long Bore Machine) with a 2 metre long measuring arm and in constant use at a leading aerospace manufacturer.

With high precision manufacturing techniques, and constructed from hand lapped granite, ELEY CMMs are the only machines that don’t require software ‘error mapping’.

Aluminium CMMs offer no benefit, other than price, to the end user. With a coefficient of expansion almost 4 times that of granite, the only issue is how to make aluminium CMMs accurate. The answer is to use an error map and force the map to make the CMM structure accurate.

Within any 3-axis device there are 21 parameters of potential error; straightness (2) per axis, pitch, yaw, roll and linearity for each axis. Squareness of each axis to each other completes the 21-parameter count.

Most CMM softwares have measurement algorithms that have been certified by a national accreditation body such as PTB; no such accreditation of vendor error map algorithms exists. Why not? Today's aluminium CMM relies totally on the validity of these complex mathematical formulae to provide volumetric 3D CMM accuracy.

Most manufacturers of aluminium CMMs also "lock-up" their error maps to prevent customer access. Maybe they are embarrassed by the magnitude of errors they are compensating for or maybe they mandate that the calibration pounds (£££'s) spent annually by CMM users belong to them as they refuse to allow others to adjust 'their maps' to correct for CMM geometry adjustments that occur with aluminium structures over time.

ELEY coordinate measuring machines have several unique features used in the construction that make them intrinsically more accurate than conventional machines.

LIST OF BENEFITS

• Built with 100% hand lapped granite for ultimate stability and strength
• X-axis is a granite wall or ‘riser’ that makes that axis ultra-stable
• On it is a V-Flat guide way, as used by machine tool companies and renowned for producing the best accuracy as they sit on a triangular point
• X-axis ‘V-Flat’ guideway has air bearings on all 4 sides, thus fulfilling metrological principles
• Y-axis bridge is mounted on 3 individual steel ball jacks, so it is ‘kinematically’ mounted and free from stress
• Y-axis bridge is a twin beam; with the Z-axis spindle located centrally between them, and perfectly balanced
• Z-axis assembly is kinematically mounted on 3 ball jacks so it is free from stress in the rest of the machine.
• The Z-axis assembly floats on air bearings that are both in top and underneath the Y-axis bridge, to prevent ‘lifting’
• Triangular spindle, with its ‘3-point’ location system provides great benefits for accuracy and stability
• Steel shaft drives to all axes driven via toothed belts attached to the motors.
• Machine covers made from anodised aluminium cover the whole of the axis, with ‘blinds’ for accessing the beam and scale. This maximises the protection for the scales etc.
• Air bearings are hand finished to the highest specification
• Certified in our own UKAS accredited lab to ISO 10360-2, ELEY were the first CMM company in the world to attain ISO 10360.