To achieve the best results and prevent problems like tool wear, poor surface finish, and even part damage, it is essential to select the appropriate cutting tools, feeds, and speeds when CNC machining nylon. Here's a breakdown of some key factors to consider:
Cutting Tools:
- Material: For most nylons, High-Speed Steel (HSS) is a good place to start because it strikes a balance between price and performance. Consider Carbide Tipped (TCT) or Diamond-coated tools for enhanced wear resistance and faster machining when working with glass-filled nylons or larger production volumes.
- Geometry: Ball nose end mills are perfect for curved surfaces, but end mills with two to four flutes are usually used for general milling. To ensure smooth chip evacuation, take into account chip flute angles of between 10 and 15 degrees.
- Diameter: Select tool diameters that correspond with the sizes of your features; stay away from extremely thin tools that may vibrate or deflect.
Feeds and Speeds:
- Cutting Speed (VC): Generally speaking, nylon can withstand cutting speeds up to 200–300 feet per minute (61–91 meters per minute), which is faster than some metals. Initiate at reduced velocities and modify according to the particular material, kind of tool, and shape of the component.
- Feed Rate (F): Ensure optimal chip formation and prevent excessive heat buildup by maintaining moderate feed rates. As a starting point, aim for 0.002 to 0.008 inches (0.05 to 0.20 mm/tooth).
- Depth of Cut (DOC): Make shallow cuts to reduce tool deflection and guarantee the best possible chip evacuation. Start with DOCs between 0.5 and 1.3 mm (0.020 to 0.050 inches), and then adjust according to the material properties and tool diameter.
