What is CNC milling?
A rotating cutting tool removes material from a workpiece along a programmed path. Parts may include pocketed plates, sensor brackets or robot gripper adapters. The 3D model defines the shape; the engineering drawing communicates requirements that geometry alone cannot show.
- Identify mounting faces, fixing holes and assembly datums.
- Check internal radii, pocket depths and tool access.
- Show interfaces with adjoining components and functional dimensions.
3-axis or 5-axis milling: what matters in the enquiry
The number of axes is not a quality grade. The process depends on access, orientations and workholding. A component made in several setups on a 3-axis machine may need a different cycle on a 5-axis machine. Let the supplier assess the process unless your project has specific constraints.
- Identify surfaces whose relationship must be maintained between setups.
- Flag deep cavities, undercuts and thin walls for review.
- Distinguish essential geometry from features that could be changed.
Specify the material and the tolerances you need
Steel and aluminium describe material families, not complete specifications. State the grade, supply condition and treatments. Relate critical tolerances to identifiable datums and function. General tolerances must be agreed and referenced on the drawing.
- State the exact grade and any permitted alternatives.
- Dimension fits, locations and critical surfaces against clear datums.
- Clarify whether final dimensions apply before or after treatment.
Files for a CNC milling quote
Prepare a STEP model and dimensioned PDF with matching part number and revision. Add quantity, possible repeat batches and required delivery. Resolve or explain any disagreement between the model and drawing before sending them.
- STEP: check units, solid geometry and revision.
- PDF: include material, functional dimensions, surface texture and deburring notes.
- Enquiry: state quantity, finishes, inspection documents and delivery date.
This resource is informational. Requirements, feasibility and the inspection plan must be checked against the drawing and agreed for the supply.
Technical reference: Protolabs ↗