In our 12 factors article we described the variables that influence price, and in our country comparisons the differences by item. This article takes a step back and shows the calculation itself: when a supplier says €9.80 for a Ø30×80 mm shaft, where does that figure come from? Knowing the calculation gives you the power to evaluate quotes and to reduce cost through design.
The Price Formula
Unit price = Raw material + (Cycle time × Machine hourly rate) + Set-up ÷ Quantity + Secondary operations + Quality/documentation + Overhead and margin
Let us go through each item in turn.
1. Raw Material Cost
Turned parts are mostly cut from bar. The bar diameter is chosen 1.5–3 mm larger than the maximum part diameter (surface clean-up allowance). Length: part length + cut-off width (2–4 mm) + facing allowance (1–2 mm). On a Swiss-type lathe, the "remnant" that cannot be held at the end of the bar (200–300 mm, 5–10% relative to bar length) and, on a conventional lathe, the chucking allowance are also added to scrap.
Weight (kg) = π/4 × D² × L × density (D and L in metres; density of steel 7,850 kg/m³; aluminium 2,700; brass 8,500).
Example: Ø32 bar × 84 mm length, steel: π/4 × 0.032² × 0.084 × 7,850 ≈ 0.530 kg. With a 5% remnant allowance, 0.557 kg. 42CrMo4+QT bar price ~€2.20/kg → €1.23. Chip scrap is sold back (steel €0.15–0.25/kg), giving a small reduction; it is usually ignored in quote calculations or absorbed in the margin.
Cost tip: choosing a standard bar diameter (Ø32 bar for a Ø30 part; a Ø31 part needs Ø35 bar, 25% more material and more chip-removal time) directly affects the price.
2. Cycle Time
Cycle time = cutting times + tool change and positioning (non-cutting) times + loading/unloading (bar feed on a Swiss-type lathe, automatic). Cutting time calculation:
- Spindle speed: n = (1000 × Vc) / (π × D). Vc cutting speed (m/min): 42CrMo4+QT with carbide tooling, roughing 180–220, finishing 220–280; aluminium 400–800; brass 300–500; stainless 1.4404 120–180.
- Turning time (min): t = L / (n × f). L machining length (mm), f feed (mm/rev): roughing 0.25–0.4, finishing 0.08–0.15.
- Number of passes: (Bar diameter − part diameter) / 2 / depth of cut (roughing 2–4 mm, finishing 0.3–0.5 mm).
- Drilling: t = depth / (n × f); drill feed 0.1–0.25 mm/rev.
- Threading: Thread length × number of passes (6–10) / (n × pitch); Vc is reduced for threading (80–120).
- Cut-off (parting): Radius / (n × f), f 0.05–0.1; 10–20 seconds typical.
Non-cutting times: tool change 1–3 seconds (on a lathe turret), positioning to cut start 1–2 seconds; 20–40 seconds for a part with 8 tools. Measurement and in-process inspection (the operator measuring every Nth part) is added to cycle time at 3–8%.
Example shaft (Ø30×80, 42CrMo4+QT): Ø32→Ø30 roughing 1 pass + finishing 1 pass (80 mm), Ø20 h7 step 25 mm (roughing 3 passes + finishing), Ø8 hole 20 mm, M12 thread 15 mm, 2 chamfers, groove, facing, cut-off. Approximate calculation: rough turning 0.55 min, finish turning 0.45 min, drilling 0.15 min, threading 0.25 min, groove-chamfer-facing 0.3 min, cut-off 0.2 min, non-cutting 0.5 min, measurement allowance 0.15 min → ≈ 2.55 min (153 s). Completed on one machine (live-tool lathe, back-working with sub-spindle).
3. Machine Hourly Rate
The hourly rate is the total cost the shop must carry in one machine hour:
| Component | Typical share | Note |
|---|---|---|
| Machine depreciation and financing | 20–30% | €250,000 CNC lathe, 8–10 years, 4,000–5,000 hours/year |
| Operator labour (per machine) | 30–45% | Falls with multi-machine operation; the item that varies most by country |
| Tooling and consumables | 8–15% | Carbide inserts, drills, taps; higher for hard materials |
| Energy | 5–10% | 15–25 kW average draw; depends on country prices |
| Maintenance, coolant, oil | 5–8% | |
| Building, insurance, general operations | 8–12% |
Result: in Turkey a 3-axis CNC lathe costs €28–40/hour, a Swiss-type lathe €25–38/hour, a live-tool lathe €32–45/hour; in Germany roughly twice these. Taking €38/hour for the example shaft: 2.55 min × 38/60 = €1.62.
4. Set-Up and the Effect of Quantity
Set-up: writing/editing the program (CAM, 20–90 min), tool preparation and presetting (20–40 min), chuck/jaw or guide bush change (15–45 min), first-part machining and measurement (15–30 min). Typical total 1.5–3 hours; 4–6 hours for complex parts. Set-up hourly rate €30–45. Example: 2 hours × €40 = €80. Divided by quantity: €8.00/part at 10 pieces, €0.80 at 100, €0.08 at 1,000. On repeat orders the program already exists, so set-up is 30–50% shorter.
5. Secondary Operations
Heat treatment (hardening, quench and temper: €0.8–1.5/kg + batch minimum), grinding (for h6/h7 diameters, €1.5–4 per diameter), coating (zinc €0.10–0.30/part in bulk; nickel and hard chrome by surface area), marking (laser €0.05–0.20), deburring and washing (€0.05–0.30), packaging (€0.03–0.20). A 5–10% freight and handling share is added for sub-supplier operations. On the example shaft, if the h7 diameter can be achieved by finish turning, no grinding is needed; grooves and chamfers are done on the lathe; only washing/oiling €0.08 and packaging €0.05.
6. Quality and Documentation
Series inspection (sampling measurement by the operator) is in the cycle-time share; additionally the inspection report (15–60 min of quality staff per batch), the 3.1 certificate (from the material supplier, €0–25 per batch), FAI (1–3 hours on the first order). Divided by quantity: €0.20–0.50/part at 100 pieces.
7. Overhead and Margin
Costs not loaded directly onto the machine, such as sales, planning, purchasing, accounting and quality management (10–18%), and profit (8–15%) are added as a percentage of total production cost; in industry practice 20–30% together. Price competition and the customer relationship determine this band.
Example: Ø30×80 mm 42CrMo4+QT Shaft at Three Quantities
| Item | 10 pcs | 100 pcs | 1,000 pcs |
|---|---|---|---|
| Raw material | €1.23 | €1.23 | €1.18 (bulk bar discount) |
| Machining (2.55 min × €38/h) | €1.62 | €1.62 | €1.52 (cycle optimisation) |
| Set-up (€80) | €8.00 | €0.80 | €0.08 |
| Washing + packaging | €0.13 | €0.13 | €0.11 |
| Quality / report / 3.1 | €2.50 | €0.35 | €0.12 |
| Production cost | €13.48 | €4.13 | €3.01 |
| Overhead + margin (25%) | €3.37 | €1.03 | €0.75 |
| Unit price (EXW/FCA) | ≈ €16.85 | ≈ €5.16 | ≈ €3.76 |
From 10 to 100 pieces the price falls to a third; from 100 to 1,000 it falls by only 27%. Set-up amortisation determines everything at small quantities; at large quantities machining time and raw material are decisive. For this reason, ordering 2 × 500 instead of 4 × 250 for an annual need of 1,000 pieces lowers the unit price (to be balanced against inventory cost).
Cost Levers for the Designer
- Standard bar diameter: Bring the maximum diameter 1.5–2 mm below the standard bar.
- Put tolerance where it is needed: h7 on a single diameter is achieved on the lathe; two or three h6 diameters require grinding (+€2–4/part). Details are in our tolerance article.
- Length/diameter ratio: Above 10:1 requires support (tailstock, guide bush); time and scrap increase.
- Thread length: Unnecessarily long threads increase the number of passes; 1.5×D is sufficient.
- Deep small holes: Deep-hole drilling above 10×D requires special tooling and low feed.
- Material selection: Materials with high machinability (free-cutting steel, 6082, CW614N) shorten cycle time by 20–40%; if strength is required, stay with 42CrMo4 quenched and tempered steel. Our free-cutting steel article contains a comparison.
- Surface finish: Ra 1.6 is standard on the lathe; Ra 0.4 requires a finishing pass and low feed (time +15–30%), Ra 0.2 requires grinding.
- Quantity and batches: Share the annual quantity; the supplier plans bar purchasing and set-up accordingly.
Frequently Asked Questions
Should set-up be shown as a separate item in the quote?
For comparability, yes: a "unit price + set-up per batch" structure lets you calculate the price at different quantities. Some suppliers bury set-up in the unit price; ask for it to be separated.
Why do quotes for the same part differ by 30%?
Machine type (Swiss-type vs. conventional lathe), hourly rate, cycle-time estimate, margin expectation and capacity utilisation; also differences in scope (certificate, report, packaging). Our RFQ guide explains how to equalise the scope.
Can I ask the supplier for the cycle time?
Not every supplier shares it, as it is commercial information; but you can get an approximate answer to "how long is the machining time?". Asking for a price breakdown (material / machining / set-up / secondary) is more common.
Is the price calculation different for milled parts?
The logic is the same; the differences: raw material is plate/block (chip ratio may be 50–80%), several set-ups (number of clampings), more tools, a somewhat higher hourly rate. Our axis article explains the effect of clampings.
Conclusion
Turned part price = raw material + cycle time × hourly rate + set-up ÷ quantity + secondary operations + quality + overhead and margin. A buyer who knows this breakdown compares quotes correctly, and a designer determines 20–40% of the price at the design stage through bar diameter, tolerance and material selection. Tornelle quotes with this breakdown, in quantity tiers and with set-up shown separately; to see the calculation for your own part, send your technical drawing via our quote form. For our turning capacity, see our CNC turning page.
