CNC (Computer Numerical Control) machining, a precision material removal process, utilizes high-speed rotating cutting tools to accurately carve out desired shapes from solid materials. The cutting tools—critical to achieving dimensional accuracy—typically feature cylindrical shanks with limited cutting lengths, imposing constraints on deep cavities, narrow slots, and complex geometries. Strategic design adjustments can significantly reduce manufacturing expenses while maintaining quality standards.

CNC milling tools cannot produce perfectly sharp internal corners due to their cylindrical geometry. Smaller corners require finer tools, increasing machining time and tool breakage risks. The recommended minimum internal radius (R) correlates with cavity depth (H) through the formula:

R = (H/10) + 0.5 mm
Tool Diameter (D) = H/5 mm

For example, a 30mm-deep cavity requires an R≥3.5mm and a 6mm-diameter tool. Below is a reference table for tool dimensions and achievable radii:

Note: Sharp corners necessitate secondary processes like EDM (Electrical Discharge Machining) or structural redesign, both increasing costs.

Key considerations for threaded holes:

• Specify thread parameters (major/minor diameters) following ISO standards.
• Ensure uniform pilot hole diameters (e.g., ⌀2.5mm for M3×0.5 threads).
• Limit thread length to ≤3×hole diameter; blind holes require 0.5×diameter clearance at the bottom.

Optimal cutting depth is 2–3×tool diameter. Cavities exceeding 5×diameter risk tool deflection and require specialized equipment. Recommended maximum depth: 5×XY planar dimensions.

Minimum recommended thicknesses:
Metals: 0.8mm (absolute min 0.5mm)
Plastics: 1.5mm (absolute min 1.0mm)

Standard tolerance is ±0.1mm unless specified. Tighter tolerances require additional machining and inspection time.

Supplement 3D models with annotated 2D drawings specifying:

• Critical tolerances
• Surface finishes
• Assembly interfaces
• Thread details (parameters/depth)