Requirements and DFM
Review the current drawing, function, material, quantity and open questions. Agree the manufacturing and inspection scope in the quotation.
Overview of CNC Machining: Processes & Principles
Understand which CNC process fits a part’s main features, what a supplier needs to review, and how a drawing becomes an agreed machining and inspection plan.
When this guide applies
CNC (computer numerical control) machining uses computer-controlled tools to remove material from stock and create the features on a drawing. Use this overview to recognize likely processes: milling for pockets and faces, turning for round features, five-axis milling for complex access, and wire EDM for suitable conductive profiles. A part can need more than one.
You do not need to choose the complete route before contacting a supplier. Share what the part must do, the available model or drawing, material and quantity if known, and the interfaces that matter. A design for manufacturability (DFM) review examines access, workholding, material and requirements before the route and quotation are confirmed.
For equipment limits and project coordination, use CNC machining capabilities. For detailed requirements, use CAD and drawing preparation.
Subtractive vs other manufacturing
| Type | How it works | Examples | Vs CNC |
|---|---|---|---|
| Subtractive (CNC) | Removes material from stock | Milling, turning and wire EDM | Review tool access, stock form, material removal and final feature requirements. |
| Additive | Builds geometry layer by layer | Polymer and metal printing processes | Can suit internal features or different stock needs; material properties, finish and any post-machining depend on the specific process. |
| Formative | Shapes material using a mold, die or other forming tool | Molding, casting and forging | Review tooling, quantity, changes and any final machining alongside the complete part cost. |
CAD to delivery — five stages
Process and toolpath planning
Select stock, machining stages, fixtures and toolpaths for the agreed features. Confirm changes with the drawing owner.
Setup and machining
Locate and hold the stock, set tooling and offsets, and machine the planned features with the required process checks.
Finishing and final checks
Complete ordered heat treatment, coating or assembly in the agreed sequence. Check critical features in their specified acceptance state.
Records and delivery
Supply the documents and protected packaging agreed for the order. Confirm production and transportation timing separately.
Common machine types
| Machine | Motion | Typical work | Well suited for |
|---|---|---|---|
| 3-axis milling | X, Y, Z | Pockets, faces, holes, slots | Prismatic parts and simple contours |
| 5-axis milling | X, Y, Z + two rotary | Sculpted surfaces, angled holes | Compound angles and multi-face access, subject to tool, fixture and rotary clearance |
| CNC turning | X, Z (+ live tooling) | Outside/inside diameters (OD/ID), grooves and threads | Shafts, bushings, housings |
| Swiss-type | Sliding headstock multi-axis | Small or slender turned features | Drawing-defined shafts, pins and threaded components |
| Wire EDM | Wire path in conductive stock | Conductive profiles, narrow slots and internal corners with a finite radius | Punch/die, intricate profiles after heat treat |
Practical process selection
- Pockets, flat faces and hole patterns: start with CNC milling. Review cutting and fixture access.
- Diameters, shoulders and threads: start with CNC turning. Length, support and any side features affect the route.
- Compound angles or access from several faces: review five-axis machining. Indexed or simultaneous motion and the setup count depend on the part.
- Hardened conductive profiles or narrow through-slots: review wire EDM. Confirm wire entry, corner radius, material condition and surface requirements.
A process name does not establish the finished tolerance or inspection coverage. Identify the functional requirements, then confirm the route through DFM. See functional tolerances and GD&T.
For example, a flanged shaft may use turning for its diameters and a live-tool or milling operation for cross-holes and flats. A pocketed housing with a narrow through-slot may combine milling with a wire-cut profile. Identify those features on the drawing when asking the supplier to compare routes.
What goes wrong with the wrong process choice
Access is assumed from CAD
A pocket or angled hole can be blocked by the tool holder or fixture. Show the critical features and allow the route to be reviewed.
Round features use an unsuitable setup
Review rotational features, support and locating relationships together. A turning or turn-mill route may be suitable, with milling where needed.
Material condition is left open
Heat treatment and hardened stock affect the machining and final-sizing sequence. Confirm which operations happen before acceptance.
Secondary operations are omitted
Specify finish, heat treatment, assembly and final inspection so the quotation includes the complete required route.
What to include in your process RFQ
- Available model and current drawing, with units and revision identified; STEP and a marked PDF are recommended.
- Material grade and condition, quantity and target delivery if known.
- The part’s function, critical faces, holes, fits, threads and any finishing needs.
- Open questions about the process, plus required inspection and records.
The RFQ form requires a project summary, name, company and email; technical fields and attachments are optional. See quote preparation and upload formats. Request a Quote even if the route is undecided. With a complete RFQ, we typically respond within one business day; complex multi-process projects may take 1–2 business days.
Ready to start your CNC project?
Describe the part and your open questions. A model or drawing helps us review the process route before a quotation.