Optical encoders support latest CMMs

RENISHAW enhances the COORD-3 customer solution with products that increase CMM throughput, accuracy and automation, resulting in increased sales backed by a strong global support network. Renishaw has also built valuable synergies with COORD-3 to support its demanding product design strategies.

Since 2009, we have launched at least two products per year into the market. Our new bridge-type Universal CMM family features a brand-new design and was launched - only one year after the project started, said Marketing manager for COORD-3, Patrizio Vaccaro. 

The COORD-3 is one of the few suppliers to manufacture its CMM structures from aluminium alloy and silicon-carbide, offering maximum metrology performance and productivity.

Even in a lab with environmental control, traditional granite CMM frames have significant thermal mass and take much longer to absorb and dissipate thermal changes, whereas, aluminium's high coefficient of thermal conductivity allows the machine structure to respond more rapidly and linearly with temperature fluctuations.

This is important as it is necessary to predict CMM thermal behaviour and compensate for it in order to ensure machine accuracy over its operating temperature range. CMMs that expand linearly without induced constraints are easier to compensate for, which improves measurement repeatability.

The low structural weight of aluminium also improves the CMM's acceleration and deceleration - enhancing overall traverse speed and ultimately increasing measurement throughput.

This allows the CMM to operate at relatively high speed, which is particularly important for in-line applications where inspection operations need to keep pace with production.

Renishaw provides real-time temperature compensation with its 3-axis UCC S3 and 5-axis UCC T5 controllers, allowing temperature monitoring of up to 16 different locations, using sensors which can be fixed to the X, Y, and Z axes of the CMM and to the workpiece being measured. The thermal data is then combined with axis feedback from the TONiC encoder system to produce high fidelity measurements that allow the machine to minimise thermal error and reduce measurement uncertainty.

Fabrizio Tonellato, COORD-3's principal electronics engineer, explains:

“The main challenge with CMMs is ensuring measurement repeatability. Renishaw's TONiC encoders with FASTRACK have solved the problems associated with differential thermal expansion between the scale and machine axis on which it is applied. Strong points of the TONiC encoder series include: high measurement precision, linear thermal expansion of scale due to CTE of scale, ease of installation and set-up and easily replaceable FASTRACK scale for straight-forward maintenance.”

Mr Vaccaro emphasises: “Scales and readheads are of primary importance for CMMs and TONiC with FASTRACK embodies the COORD-3 design philosophy. Different materials are used to build a CMM and Renishaw's encoder scales help minimize the CMM measuring error and maximize precision.” Mr Vaccaro adds: “COORD-3 CMMs are built largely from aluminium and Renishaw's encoders help to compensate for expansion and thermal movement. In creating our CMMs, we are not bound in the choice of the materials because Renishaw's FASTRACK mounted scale is largely free to expand independently of the machine structure. TONiC with FASTRACK and the UCC S3 / T5 controllers are stable, flexible and well-designed products, which have helped to triple our sales.”