The Difference Between Milled and Turned Parts — And When Each Process Is the Right Call
Milled parts manufacture versus precision turning: it is one of the first decisions a design or procurement engineer makes when a new component goes out for quote. Get it right and you get accurate parts at a fair price. Get it wrong and you either pay more than you need to, or end up with parts that do not perform as intended.
This guide covers how each process works and how to decide which one your application needs.
What Milled Parts Manufacture Involves
Milled parts manufacture starts with a block or billet of raw material and removes material through a series of controlled cutting passes. The CNC milling machine follows a programmed path derived from your CAD model, working across multiple axes to produce the finished geometry.
Milling suits components that are prismatic in nature: housings, brackets, plates, manifolds, and structural elements with flat faces, angular profiles, pockets, and slots. What milled parts manufacture does not favour is high-volume production of rotationally symmetric parts. That is where precision turning comes in.
How the Manufacture of Precision Turned Parts Differs
The manufacture of precision turned parts works on the opposite principle. The workpiece rotates at high speed on a lathe while a fixed cutting tool removes material, producing cylindrical or conical profiles: shafts, pins, bushings, fittings, and threaded components.
The advantage of turning is speed and consistency on rotationally symmetric geometries. Once a program is set and tooling dialled in, a CNC lathe can produce identical parts in rapid succession to very tight tolerances. Modern lathes with sub-spindles and driven tools can also combine turning, milling, and drilling in a single setup, reducing handling and tolerance stack-up.
Where the Two Processes Overlap
Complex components often involve both processes. A turned shaft may need a milled flat or keyway. A milled housing may need a turned bore. If the dominant geometry is rotational, a turned parts manufacturer is your starting point. If it is prismatic or three-dimensional, milled parts manufacture is the appropriate route. Where both are clearly present, a manufacturer capable of handling both avoids the lead time and tolerance risk of splitting the work across suppliers.
Tolerances, Materials, and Cost
Precision turning can hold diametral tolerances below ±10 µm on cylindrical features, making it well suited to bearing fits, thread quality, and shaft diameters. Milled parts manufacture applies tolerances across a wider range of feature types: flatness, parallelism, perpendicularity, and positional accuracy of holes and pockets, typically in the range of ±0.01 mm to ±0.05 mm on most features.
Both processes work across aluminium, steel, stainless, brass, copper, titanium, and engineering plastics. Material choice should be driven by the functional requirements of the application, not by process limitations. On cost, turning is generally more efficient for high-volume symmetric parts due to shorter cycle times and automation capability. Milling is more flexible for low volumes and complex geometries. Neither has a blanket advantage.
Not sure which process suits your component? Send Prenco your drawings and we will advise
Working With Prenco
Prenco Manufacturing Ltd., based in Skibbereen, West Cork, handles both milled parts manufacture and the manufacture of precision turned parts from a single facility. Our precision turning operation runs on a SPINNER PD lathe and a Doosan Lynx 2100 LSYA with sub-spindle and driven tools. We hold tolerances below ±10 µm and are accredited to ISO 9001:2015.
If you have a component that could go either way, or a job that involves both, send us your drawings and we will talk through the right approach. Get in touch with the Prenco team to know more.
Frequently Asked Questions
Milled parts are produced by moving a cutting tool across a stationary workpiece to create prismatic shapes: flat faces, pockets, slots, and complex profiles. Turned parts are produced on a lathe where the workpiece rotates to create cylindrical or conical shapes. The geometry of your component determines which process is appropriate.
Milled parts manufacture suits components with prismatic geometry: brackets, housings, plates, and manifolds. If the primary features are flat faces, angular profiles, or complex pockets, milling is the right process.
A turned parts manufacturer is the right choice for cylindrical or conical components: shafts, pins, bushings, fittings, and threaded parts. Turning is also more efficient for high-volume production of rotationally symmetric parts.
Yes, and this is common. Modern CNC lathes with driven tooling can combine both operations in a single setup for many components. For more complex combinations, working with a manufacturer who handles both processes avoids lead time and tolerance risk.
Milled parts manufacture works across aluminium, mild steel, stainless steel, brass, copper, titanium, and engineering-grade plastics. Material choice should be driven by the functional requirements of the application.
Send your drawings or CAD files along with material, quantity, and tolerance or finish requirements. The team will review the job and come back with a clear price and lead time. Call 028 21399 or email info@prenco.ie.
CONTACT US
Prenco Manufacturing Ltd, Baltimore Road,
Prenco Manufacturing Ltd,
Baltimore Road,
Skibbereen,
Co. Cork, Ireland.
Tel: 028 21399
Email: info@prenco.ie
