Multi-axis coating machine handles high volume throughput

15 February 2011

A real-time Ethernet motion control system has helped Advanced Coating Robotics (ACR) to create a new conformal coating machine that combines exceptional three-dimensional spraying accuracy with high throughput.

The multi-axis system is based on Baldor Electric motion control products, with three axes making use of the company's Ethernet-compatible PowerLink servo drives.

Key reasons behind the choice of this motion control technology were the flexibility of Baldor's motion control software, the ease with which real-time interpolated control could be applied across the machine's five-axis servo and stepper driven motion, and the plug-together system building approach that is offered by the Ethernet-based modules.

ACR's new MACCS 400 machine is designed to enable the selective application of protective conformal coatings to PCB-mounted components, accommodating both inline and batch processing operations.

Capable of coating PCBs as large as 500 x 480mm – with on-board components as high as 90mm – the programmable machine uses a five-axis motion control system to combine high-speed throughput capabilities with a precise spray head positioning to an accuracy of 25 microns.

The X and Y axes of the machine's motion control system are based on a novel 'H-belt' actuator, driven by two Baldor BSM servomotors linked to Baldor MicroFlex e100 drives. The two motors occupy fixed positions at the bottom of the 'H' - and jointly act on a single belt. This means that the motors do not contribute to the load inertia, and therefore permit very fast and accurate movement – the machine can accommodate X-Y velocities as high as 800mm/sec. The Z-axis controls the above-board height of the spray head, and is driven by a third BSM servomotor and MicroFlex e100 drive. All three drives are tightly synchronised to facilitate high speed Cartesian movement of the spray head, the angle and orientation of which are controlled by two rotary axes, driven by Baldor stepper motors.

All five electrical axes on the MACCS 400 are controlled by a Baldor NextMove e100 controller, using full interpolation to allow smooth high speed tangential moves. Overall control of the machine is handled by ACR's proprietary coating software, which runs under Windows XP on a built-in host PC, equipped with a large HMI. The coating software provides an intuitive graphical user interface and is written in the VB.NET object-oriented programming language.

According to ACR's Managing Director, Gordon Watson, the choice of motion control technology was influenced by the flexibility of Baldor's NextMove controller, which interfaces seamlessly with the company’s software. He said: “Baldor's software development environment, which comes as part of the package, includes comprehensive support for ActiveX, which fits well with VB.NET. Creating the complex real-time motion control sequences was relatively easy, as Baldor's Mint language employs high level keywords for many of these moves.”

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