Rotary stage boasts "best-in-class" accuracy

The ARA125 tangent rotary stage combines noncontact direct drive technology with a very low profile for demanding manufacturing, production and inspection alignment applications.

Aerotech's novel ARA125 tangent rotary stage combines noncontact direct drive technology with a very low profile for demanding manufacturin,g production and inspection alignment applications where exceptionally high positioning accuracy and very low resolution needs to be combined with high speed, rapid acceleration and a compact design.

The ARA125 takes full advantage of the fact that many high-throughput positioning applications require rotary axes with only partial angular travel for very fine alignment; for example to compensate for substrate straightness and flatness or for extremely fine focusing.

In such applications, traditional worm-wheel gearbox based solutions would use only a fraction of their full travel range and factors such as machined accuracy limitations and high system friction would seriously limit their performance for the vast majority of applications.

Typically, only the most expensive worm-wheel stages would meet such high specification requirements and even then it would require extensive testing and calibration to establish and select the most accurate section of the travel range to use.

In addition, factors such as the high maintenance required to combat mechanical wear and their large size would make worm-wheel solutions an unattractive choice.

By designing the stage around a partial rotation specification, Aerotech has developed a patent pending, "curvilinear" direct drive, brushless motor and integral high resolution encoder.

This noncontact, friction free solution is effectively a high performance linear motor built on to a curved support and the resulting specification has effectively moved the benchmark for competitively priced rotary alignment systems.

The ARA125 has a 15-degree rotation range that offers zero backlash, ultrasmooth and precise angular motion capable of positioning to within +/-1arc-sec and speeds of up to 250degree/s.

The stage has a 125mm diameter table top with a 30mm clear aperture and at just 63.5mm high, the low profile unit will minimise stack-height related errors in multi axis applications.

The complete assembly weighs just 4.5kg and is housed within a compact 203 x 203mm footprint which includes motor and encoder connectors; a 20kg central loading capability allows its use in applications requiring minimum size and maximum performance.

This breakthrough technology offers best-in-class accuracy for rotary alignment in high-throughput production and inspection applications such as wafer manufacture, hard drive inspection systems, laser and ion beam micromachining, disk drive test/servo writing, nanotechnology and many applications where very precise rotary alignment is required.

Designed for extremely long life and low maintenance, the ARA125 is manufactured from aluminium with a black anodised body and a Teflon "hardcoat" finish for the table top.

The impressive specification for the stage includes a calibrated accuracy +/-1arc-sec, and bidirectional repeatability of just +/- 0.5arc-sec with axial and radial runout figures of 1.0 and 2.5um, respectively, measured at 75mm above the table top.

A choice of encoder options allows a positioning resolution of 0.036 to 3.6arc-sec; the finer resolution option has a reduced maximum speed dependant upon the data rate of the control system.

These self-contained rotary stages may be supplied as separate units with interconnecting cables or within multi-axis positioning systems complete with servo drive, motion and machine controls such as Aerotech's Automation 3200, a software based machine control system combining motion, HMI, PLC and vision control modules using the industry standard Firewire high performance communication network and capable of controlling up to 32 axes of high speed motion; additionally a 10/100Base-T Ethernet interface may be used to add third party I/O and PLCs.

Such systems are supplied with all motor and encoder feedback connectors, performance and calibration related documents and a CD with complete interconnection drawings are included along with motor parameter setup data for the software configuration file to suit the control and drive selected.

Aerotech builds these features into all its products and offers comprehensive technical support and product training, ensuring that the true cost of ownership is extremely competitive and that system commissioning is straightforward, requiring little more than connecting cables and applying power before programming application software.

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