# Calculate the cost of a CNC-milled part from its CAD model.
URL: https://arcnm.io/manufacturing/cnc-milling
Language: en

To cost a milled part, you need its features and the setups it takes. You also need the cutting time per feature and the machine-hour rate. ARCNM reads all of that from the STEP file and the drawing. It recognises pockets, holes, threads, chamfers and faces. It plans the setups on a 3-axis, 3+2 or 5-axis machining centre. It computes setup and cycle time for every operation. Then it returns a unit cost for every lot size. You can trace each number to the feature that caused it.

## At a glance
- Inputs: STEP model; PDF drawing optional (tolerances, finish, treatments)
- Machine classes: 3-axis VMC · 3+2 indexed · 5-axis · drill press
- Standards applied: ISO 513 material groups · ISO 286 / 1101 / 2768 tolerances · DIN 8580
- DfM checks: deep hole, blind deep hole, thread near hole bottom, pocket depth-to-width, sharp internal corner, slot aspect ratio, thin wall, undercut, face not 3-axis reachable
- You get: routing with setups, cycle and setup time per operation, unit cost per lot size, machine class chosen per quantity, cost drivers ranked

## What do you get for a milled part?
You get a complete routing: the setups on the machining centre and every operation. The operations include face milling, pocketing, drilling, reaming, tapping, boring and thread milling. Each has its setup and cycle time on the machine chosen for the lot. An aluminium bracket and a titanium housing are each costed at their own cutting speeds. The machine-hour rate comes from your own fleet. Every euro on the cost sheet traces back to the feature that caused it.

## What does a milled part cost, and what drives the price?
Setups first: every re-clamp adds fixed time that only amortises with the lot. Then removed volume, tight tolerances and fine finishes. A surface goes to grinding when milling cannot hold its callout. Deep pockets, thin walls and the number of tools add to the price. ARCNM names each driver with its share of the unit cost. So you know whether to challenge the tolerance, the material or the lot size.

## Which milling features and checks are covered?
- Features from the 3D model: pockets, bosses, holes, counterbores, threads, slots, chamfers, fillets, ribs, faces — with stable IDs.
- Machine classes: 3-axis VMC, 3+2 indexed, full 5-axis. ARCNM picks the cheapest feasible class at every lot size.
- DfM flags graded by severity: deep pocket, thin wall, small internal radius, unreachable feature, undercut.
- Tolerances and GD&T from the drawing (ISO 286, ISO 1101, ISO 2768, ASME Y14.5) bound to the faces they constrain.

## 3-axis, 3+2 or 5-axis — which machine class wins?
| Machine class | Reaches | Setups on a typical bracket | When it wins |
| --- | --- | --- | --- |
| 3-axis VMC | one face per clamping (the top; vertical walls by the tool flank) | 3–5 | simple prismatic parts, large lots (lowest hour rate) |
| 3+2 indexed | five sides in one clamping | 1–2 | multi-side parts where re-clamping dominates |
| 5-axis simultaneous | compound surfaces, undercuts | 1 | complex geometry, small lots, tight positional tolerances |

## FAQ
**Can I calculate the price of a milled part from a STEP file alone?**
Yes. The STEP geometry is enough for features, setups and cycle time. Add the PDF drawing, and ARCNM also reads tolerances, surface finish and treatments. These usually move the price more than the geometry does.

**How much does one hour of CNC milling cost?**
The machine-hour rate of the machine in your fleet. It covers depreciation, interest, floor space, energy and maintenance over the running hours, plus the operator's attended share. ARCNM builds it from your fleet instead of quoting a market average. Start with the reference rates. Then calibrate to your shop with a handful of real costs.

**How do I calculate the machining time of a milled part?**
A milled part's machining time is the sum of its operations' cycle times. ARCNM computes each cycle time from the removed volume and the material's cutting data on the chosen machine. Setup time per clamping comes on top, spread over the lot. The process plan shows both times for every operation.

**Why are milled parts often more expensive than turned parts?**
Milling usually needs more setups. It also removes material with an interrupted cut over a larger surface. So both fixed and variable time are higher. ARCNM shows the difference per operation. You spot a part that could be turned before it is quoted as milled.

**Which materials can ARCNM price?**
ARCNM prices 536 catalogue grades. They cover carbon, alloy, stainless and tool steels, and cast irons. They also cover aluminium, copper, titanium, nickel and magnesium alloys, polymers and composites. The grades are known under 1,913 designations from 53 standard systems. So 1.0038, S235JR, St 37-2 and Fe 360 B resolve to one grade. Each grade belongs to an ISO 513 workpiece group with its own cutting data. You can register a material the catalogue does not carry, with your own house spellings. It then prices like any catalogue grade.