Five-Axis CNC Machined Aluminum Cylinder Head
Billet aluminium cylinder heads five-axis machined from 6061-T6 or 7075-T6, with combustion chambers profiled to a matched volume, valve seats coaxial to the guides within 0.015 mm, cam bores line bored to H6 and a deck flat to 0.02 mm. Ports are blended to the gasket line so the manifold does not step into the head.
- Deck Flat to 0.02 mm
- Cam Bores Line Bored
- Chambers Cut to Volume
- Ports Matched to Gasket
*Send the cam, valve and gasket drawings together. A head is only as good as the stack around it, and the deck height is set by the cam base circle, not by the block.
Billet Cylinder Head Overview
A cylinder head is where flow, sealing and geometry meet: the deck has to seal combustion pressure, the chamber has to hold the volume the compression ratio was calculated from, and the cam bores have to stay in line while the head is hot.
The part is machined from a solid billet in three stages: roughing removes most of the mass, an intermediate pass brings the walls to 1 mm of finish, and the finishing passes cut the chambers, ports and seat pockets. Cam bores are line bored last, with the head clamped to a deck plate that reproduces the block.
6061-T6 Billet
6061-T6 is the default for a naturally aspirated head: it welds if a port needs repair, holds a chamber edge without chipping and takes a thread insert cleanly. It is also stable enough that the deck stays flat after the chamber is cut.
7075-T6 for Boosted Engines
7075-T6 is chosen when the head sees boost and the deck load is high, because its yield strength keeps the fire ring from Brinelling the deck. It cannot be welded reliably, so a port repair means a new head.
Naturally aspirated and repairable points to 6061; high cylinder pressure and a known port shape points to 7075. The chamber volume target usually decides the rest.
Billet Cylinder Head Specifications
Five-axis data for billet heads, with the deck, chamber and cam bore values that decide whether the engine seals and makes the flow it was designed for.
| Specification | Machining Data | Specification | Machining Data |
|---|---|---|---|
| Product | Billet Cylinder Head / Head Block | Machining Process | 5-Axis CNC Milling, Chamber Profiling, Line Boring |
| Material | 6061-T6 or 7075-T6 Billet | Deck Flatness | 0.02 mm over the full face |
| Combustion Chamber | Volume Matched to ±1 cm³ | Valve Seat Coaxiality | 0.015 mm to the Guide |
| Cam Bore | Ø 22 – 40 mm, H6, Line Bored | Cam Bore Straightness | 0.01 mm over 400 mm |
| Valve Guide Bore | Ø 6 – 12 mm, H7 | Port Matching | Within 0.5 mm of the Gasket |
| Deck Surface Finish | Ra 1.6 µm or Better | Spark Plug Thread | M10 – M14, Cut to Pre-Plate Size |
| Customization | Chamber Shape, Port Size, Injector Boss, Sensor Pads | Lead Time | 9 – 12 Days Sample, 18 – 24 Days Batch |
| Inspection | CMM Chamber and Cam Bores, Volume Check, Flatness on Granite | Packing | Timber Crate, Deck Face Protected, VCI Bag |
Key Features of Our Billet Heads
Chamber volume measured, cam bores line bored, deck checked on granite.
Chamber Volume Matched
Each chamber is measured by burette after machining and blended to within 1 cm³, so the compression ratio is the same across cylinders and the ECU trim stays balanced.
Cam Bores Line Bored in Place
Bores are cut with a line boring bar after the head is clamped to a deck plate, which keeps them straight to 0.01 mm over 400 mm and stops the cam binding when hot.
Seats Coaxial to Guides
The seat pocket is cut from the guide bore as the datum, holding coaxiality to 0.015 mm so the valve seals on the full face rather than on one side.
Ports Blended to the Gasket
Port openings are machined to the gasket line and blended 20 mm in, which removes the step that costs flow at the flange.
Head that has to hold volume and cam alignment?
Surface Finishes for Cylinder Heads
The deck and the chamber are functional surfaces; everything else is protection and appearance.
| Finish | Main Purpose | Finish | Main Purpose |
|---|---|---|---|
| Bead Blasting | Even matte exterior that hides tool marks | Deck Left Bare | True flat sealing surface under the gasket |
| Type II Anodizing | Colour and corrosion protection on the outside | Combustion Chamber Polished | Reduces hot spots and carbon build-up |
| Laser Marking | Cylinder number and torque sequence on the cam cover face | Thread Inserts | Repairs or upgrades for plug and sensor threads |
*The deck is never anodized or blasted. Coating on a fire ring land adds a compressible layer that relaxes after a heat cycle and shows up as a gasket leak.
Put your CNC milling parts into production today
All information and uploads are secure and confidential.
Trusted for Precision CNC Machined Components
Supporting OEM projects with accurate machining, flexible production, and reliable component quality.
Trusted for Precision CNC Milling.
Five-Axis Machining Process for Heads
The cam bores are line bored after the head is bolted to a deck plate, so the cam turns in a straight line rather than in the line the clamp load leaves.
01. Stack and Volume Review
Check the cam, valve, gasket and block drawings together, calculate the chamber volume target and confirm the deck height before any metal is removed.
02. Rough the Billet
Remove the bulk of the material in descending step-downs, leaving 1 mm on every finished face, then stress-relieve the part before the semi-finish pass.
03. Semi-Finish and Chamber
Bring walls to 0.3 mm, cut the chamber with a profile cycle and check the volume by burette, adjusting the cutter path before the finish pass.
04. Ports and Seat Pockets
Blend the ports to the gasket line, cut the seat pockets from the guide bore datum and ream the guides to H7, checking coaxiality on the CMM.
05. Line Bore Cams and Check Deck
Clamp the head to the deck plate, line bore the cam tunnels, then check deck flatness on granite and record every value before crating.
Send the head drawing with the cam and valve stack, and we will quote it with the chamber volume and cam alignment defined up front.
Billet Cylinder Head FAQs
Within 1 cm³ across cylinders, measured by burette after machining. For a race engine we match to 0.5 cm³, which needs a final blend by hand and a second measurement.
Yes, from a point cloud or a CAD surface. The port is machined to the model and blended to the gasket, but the flow bench result is only as good as the model you send.
We machine the pockets and bores to your insert drawings and can press and ream them if the inserts are supplied. Seat cutting after installation is done on a seat cutter, not on the mill.
0.02 mm over the full face, checked on a granite plate with a height gauge. Heads that are machined in two set-ups typically show 0.05 mm and need surfacing before assembly.
A billet head relaxes less than a casting, but the deck is worth re-checking after the first run-in. We leave 0.05 mm on the deck when the customer plans to surface after break-in.
Nine to twelve days including programming, roughing, stress relief, finishing, line boring and the CMM report. Batch runs of five or more take eighteen to twenty-four days.
Other CNC Machined Mechanical Components
Explore additional precision CNC machined components manufactured for OEM applications and customized production needs.
Custom CNC machined steel hydraulic manifold blocks with cross-drilled galleries and gauged ports.
Custom CNC machined stainless steel fixtures for automated assembly cells.
Precision CNC machined stainless steel rotary joint housings for robot arms and fluid transfer.
Custom CNC machined aluminum double tube clamps for motorcycle frames, bicycle builds and hydraulic lines.
Custom CNC machined hardened steel sleeves for robotic joints and motion assemblies.
Get high‑quality machined parts in as fast as 4 days with our expanded automated CNC milling!