Posted to News on 20th Feb 2007, 19:41
Rugged direct-drive linear stages offer high precision
With a ruggedised and fully sealed design, Aerotech's ALS5000 series linear stages combine direct-drive motor technology and linear motion guide bearings for high-precision positioning of large payloads in harsh production environments. The range is available in a choice of widths: the ALS5000 series (279mm wide) has seven travel range options from 200-1000mm; the ALS500WB series (571mm wide) has five travel range options 450-1000mm. The wide-base version is designed to facilitate X-Y mounting and accommodate larger offset stage loading. It also includes a dual linear motor drive to provide the extra power needed for high-speed positioning.
The ALS5000's design permits it to be used in the most demanding production application environments such as ceramic scribing and laser machining. Protecting the stage from hot sparks and debris, the hard top and integral metal waycovers have a Teflon-impregnated hard-coat finish for maximum durability and scratch resistance. An innovative tensioned side-strap seal allows free travel of the tabletop while maintaining a tight seal - further protecting the stage bearing, motor and encoder. An optional air-purge feature allows air or specialist gases to be forced into the interior of the stage, causing a positive pressure and ensuring that the stage is protected against particle ingress. Both stage width designs include ample mounting holes that can be accessed without dismantling for straightforward installation and a fully integrated chain-type cable management system is included.
A combination of direct-drive, cog-free brushless servo motors and a choice of standard-precision or high-accuracy linear encoders provide the ALS5000 series with smooth, precise, zero-backlash motion that is suitable for tightly synchronised multi-axis positioning. Also providing excellent in-position stability, the friction-free and cog-free servo motor and feedback system offers extremely long life when compared to ballscrew-driven stages.
Low-profile, compact design
The comparison with ballscrew-driven stage designs also illustrates the fact that the ALS5000 offers a lower profile and a more compact design with a smaller footprint. This comparison can be extended to cost of ownership factors such as much improved throughput, less maintenance and a greatly increased working life.
With a maximum speed of 2m/s and with load acceleration of up to 30m/s2 the ALS5000 series is available with a best resolution of just 0.001um with the high-precision encoder option and 0.005um for the standard-precision encoder. Nominal accuracy is +/-40.0um for the 1m travel version; however, stages can be supplied with the HALAR interferometer calibrated accuracy option where all travel ranges can achieve up to +/-1.0um in combination with Aerotech's A3200 Automation Platform motion control system. Stage repeatability is up to +/-0.5um, uncalibrated straightness and flatness for the standard stage is 2um per 25mm of travel with the HALSF option available to provide much higher calibrated values if required. Equally impressive specifications for pitch yaw and roll are available and, as with all Aerotech mechanical systems, are covered in detail in the product sections at Aerotech's website.
Aerotech manufactures a wide range of servo amplifiers and advanced motion controllers for complete positioning systems suitable for use across many manufacturing and research applications. These include the A3200 Digital Automation Platform with up to 32 axes of Firewire-interfaced high-performance motion and machine control. This software-based control system combines motion and optional HMI, PLC and vision control modules and is programmable in a choice of languages including Aerotech's own AEROBasic, RS274 G-code, C, C++, VisualBasic, Delphi and Labview. The Firewire distributed control architecture typically delivers fully deterministic motion updates to Aerotech's Ndrive servo drives – available in a wide choice of power ratings. Independently processing position velocity and current loops at closure rates of up to 20kHz, the combination of A3200 and Ndrives avoids the processing bottleneck associated with hardware-based single-processor control systems. An additional Ethernet 10/100 BaseT interface may be used to add third-party I/O and PLCs.
Every Aerotech system comes fully tested and includes motor power and encoder cables plus performance- and calibration-related documents. To make commissioning straightforward, each system includes a delivery pack with interconnection drawings to help integrators with their own system documentation and all motor parameter set-up data for the system configuration. Full product training and comprehensive on-line technical support is also included, making the true cost of ownership of Aerotech positioning systems extremely competitive.
