Development of a CNC Milling System for Preparation of Micrometer-Sized Samples for X-ray Nanotomography

Abstract: X-­ray nanotomography is an imaging technique used to study three­-dimensional structures at submicrometer length scale. The samples to be studied should be only 10s of micrometers in diameter, and ideally cylindrical. Focused ion beam milling is the most common technique used to prepare samples for nanotomography experiments, and the current technique used at the NanoMAX beamline of the MAX IV synchrotron facility. It is a time­-consuming process as preparing one sample can take hours. With the aim of offering a faster, alternative sample preparation method, a CNC milling setup was developed, and is presented here. The CNC setup is based on two spindles placed on precision linear stages - one for the sample and one for the milling tool. The sample is rotated while being trimmed gently by the milling tool, resulting in a small sample cylinder. A Python script generating G­-code commands controls the procedure. The setup was used to trim copper samples down to 18.5 micrometers. Further work is needed to optimize milling parameters in order to reach similar diameters for other sample materials. The developed setup offers a time-­efficient, repeatable and low­-cost sample preparation method for X-­ray nanotomography.