Laser Drilling: Achieving Fast and Precise Laser Beam Focus and Dynamic Workpiece Positioning Using a Unified Controller Approach

New whitepaper from PI explains how it’s done.

Leveraging an integrated solution from Physik Instrumente (PI), achieving nanometer-precise motion control with enhanced throughput in laser drilling is now a reality. Powered by EtherCAT drives and controllers, motion integration has been streamlined, eliminating the complexity of coordinating various control system elements.


Motion Control for Laser Drilling
Laser drilling finds rapidly growing applications, be it in manufacturing of fuel injection nozzles, aerospace component cooling holes, or microvias in printed circuit boards (PCBs). This surge is fueled by the growing trend toward miniaturization. To meet these demands, laser drilling systems must continually enhance their precision, reaching submicron accuracies.

PI's motion control and nanopositioning systems have emerged as the optimal choice for laser drilling machines, striking a balance between high throughput and exceptional precision. The system comprises multi-axis precision positioning stages for workpiece placement, a highly dynamic Z axis for precise laser focusing, and the flexibility to enhance either beam or workpiece positioning through the utilization of high-speed piezo motion.

To optimize the drilling process, PI offers a comprehensive range of ACS-based servo controls and PI piezo drives, complemented by laser-specific control options. These components significantly elevate both throughput and precision, proving indispensable when drilling deep holes with high aspect ratios while carefully managing heat affected zones (HAZ).

Achieving Nanometer Precision and High Dynamics in Workpiece Positioning
In facilitating precise motion control and positioning of workpieces during laser operations, PI offers adaptable hybrid motion solutions. These systems incorporate high-performance direct-drive linear motion stages or gantries providing travel ranges up to 2 meters. Additionally, high-speed piezo nanopositioners ensure meticulous dynamic control of the workpiece position in relation to the laser beam. Operating with nanometer accuracy and bandwidth to 100Hz, they allow the creation of intricate and complex geometries, including multi-faceted shapes adhering to specific wall constraints. The step-and-settle action occurs within milliseconds, facilitated by position feedback that offers nanometer resolution. Moreover, employing Dynamic Digital Linearization (DDL), a PI proprietary piezo control algorithm, enhances tracking performance in high-frequency applications, ultimately optimizing process quality and productivity.

The piezoelectric nanopositioners capitalize on the inverse piezo effect. When a voltage is applied, piezoelectric ceramics induce movements with resolution down to the picometer range. These movements exhibit high dynamics and exceptional repeatability. Specifically, the employment of PICMA piezo elements from PI's piezo division, PI Ceramic, in this regard ensures wear-free performance, maintaining position accuracy even after billions of cycles.

Controlling the Laser Focus with Speed and Precision
For precise vertical control of the laser focus, PI offers a highly dynamic, voice coil-driven focus motor (model V-308) capable of travel ranges up to 7mm with nanometer resolution and fast response. This feature enables the drilling of micro-holes with substantial aspect ratios and vertical edges, even in thick workpieces. The ACS motion controller orchestrates the Z focus motion in direct coordination with the workpiece positioning stages. All motion stages are seamlessly operated in closed-loop mode via the motion controller. Leveraging the versatility of the ACS controller, which also supports CNC G-code scripting, allows for a universal programming approach applicable to both programming and the powerful native ACS language. The utilization of EtherCAT simplifies engineering and commissioning processes.

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MOTION CONTROLLERS FOR MINIATURE DRIVES AND MICRODRIVES

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