When designing nylon parts for CNC machining, it's important to consider both the material's characteristics and the capabilities of the machining technique. These best practices should be adhered to:

Material properties

  • Strength and stiffness: The grade and type of nylon affect its strength and stiffness. Pick a grade that meets your requirements in terms of function.
  • Melting point: Nylon has a relatively low melting point in comparison to metals. Design features that lessen heat generation during machining are used to prevent thermal warping.
  • Moisture absorption: The dimensional stability of nylon could be affected by its absorption of moisture—parts of the design that allow for moisture expansion and contraction.

Design considerations

  • Wall thickness: Maintain consistent wall thicknesses to avoid uneven material removal and warping. Try to keep the thickness to a minimum of 1.5 mm for most applications.
  • Fillets and chamfers: When working with sharp corners, use plenty of fillets and chamfers to reduce stress concentrations and improve tool accessibility.
  • Holes and threads: Allow sufficient space for the tap depth and tool diameter when designing the holes. Consider employing self-tapping threads for a more straightforward assembly.
  • Internal features: Avoid deep pockets and cavities that are difficult to reach with machining tools. Use draft angles to facilitate tool withdrawal.
  • Ribs and bosses: Use bosses and ribs to give thin sections more strength and rigidity. Give them walls that are thick enough and rounded corners.

Tooling and machining

  • Tool selection: Choose the appropriate end mills and drills for the desired features and material. Consider using coated tools to increase chip evacuation and wear resistance.
  • Cutting parameters: Use moderate feed rates and cutting speeds to minimize heat generation and prevent tool wear.
  • Coolant: Coolant should be used to lubricate the tool and workpiece to reduce heat and friction.

Additional tips

  • Prototype and test: Verify your design with prototypes to identify potential issues before proceeding with large-scale production.
  • Consult with a machinist: Consult a machinist for advice on cost-saving measures and whether your design can be manufactured.
  • Use design software: Use CAD software to create accurate 3D models of your parts for CNC programming and simulation.