Niobium is known for its challenging machinability due to its high strength, ductility and low thermal conductivity. Processing niobium requires specialized tools, techniques and processes to achieve precise results.

Some key considerations for niobium machinability include:

1. Tools: Due to the high hardness of niobium, carbide or diamond tools are often used to process niobium. These tools can withstand the wear and tear of niobium and maintain their cutting edge longer.

2. Cutting speed and feed: Niobium has a low thermal conductivity and cutting speed and feed need to be carefully considered to prevent overheating and tool wear. Proper selection of cutting parameters is critical to achieve efficient material removal without compromising tool life.

3. Lubrication: Using the appropriate cutting fluid or lubricant is critical to reducing friction and heat during machining. This helps improve surface finish and extend tool life.

4. Workpiece clamping and fixtures: Safe workpiece clamping and fixtures are critical to minimizing vibration and ensuring stability during machining, especially when machining small or complex niobium parts.

5. Post-processing processes: Post-processing processes such as electrolytic polishing or chemical etching can be used to improve the surface finish and eliminate any residual stress generated during the machining process.

Given the challenges of niobium machining, it is important to work with experienced machinists and utilize advanced CNC machining technology to achieve the accuracy and quality required for niobium machined parts.