CNC Milled Steel Hydraulic Manifold Block
Hydraulic manifold blocks milled from 4140 pre-hardened steel: 120 × 70 × 40 mm, six working G1/4 ports, two gauge ports and Ø6 cross-drilled galleries positioned to ±0.05 mm with an 8 mm minimum wall between passages. The mounting face is flat to 0.02 mm and every block is pressure tested at 350 bar for ten minutes before it is packed.
- Galleries Ø6 at ±0.05
- G1/4 Ports, 6H Thread
- Mounting Face 0.02 mm
- Pressure Tested 350 bar
*Send the hydraulic schematic with the block drawing. We set the gallery depths and plug positions from the circuit, and a gallery drilled 3 mm too deep can break into the next passage.
Steel Hydraulic Manifold Overview
A manifold replaces a bundle of hoses with drilled passages inside one block. The passages have to meet exactly where the schematic says, the walls between them have to stay thick enough for the working pressure, and the port threads have to be square to the face so the fittings seal on the first turn.
The block is squared and the port faces are milled first, because every gallery is drilled from a port face. Galleries are drilled in stages with peck cycles, deburred through the ports, and inspected with a bore scope before the threads are cut. The finished block is plugged, pressure tested and marked with the port map.
4140 Pre-Hardened Steel
4140 at 28 HRC gives a manifold that will not creep at 350 bar and still machines cleanly enough to hold a G1/4 thread without tearing.
316L Stainless or 6082 Aluminium
316L is used for water-glycol and marine circuits, while 6082-T6 aluminium is chosen for mobile manifolds where the 1.9 kg steel block is too heavy for the valve stack.
A gallery wall under 6 mm will bulge under pressure cycling; the drawing is laid out with 8 mm as the minimum, and the bore scope confirms it.
Hydraulic Manifold Specifications
Drilling, threading and test data for blocks that carry pressure, not just fluid.
| Specification | Machining Data | Specification | Machining Data |
|---|---|---|---|
| Product | Hydraulic Manifold Block | Process | CNC Milling, Cross Drilling, Tapping |
| Material | 4140 Pre-Hardened Steel, 28 HRC | Envelope | 120 × 70 × 40 mm |
| Galleries | Ø6 ±0.05 mm, Depth 110 mm | Port Threads | G1/4, 6H, 12 mm Deep |
| Port Count | 6 Working, 2 Gauge | Mounting Face | Flatness 0.02 mm, Ra 1.6 |
| Cross Hole Angle | 90°, Position ±0.10 mm | Plug Threads | G1/8, 6H |
| Wall Between Galleries | 8 mm Minimum | Edge Break | 0.5 mm × 45° |
| Pressure Test | 350 bar, 10 min, No Leak | Weight | Approx. 1.9 kg |
| Inspection | CMM, Bore Scope, Pressure Rig | Batch Size | 5 to 500 Pieces |
| Finish | Black Oxide or Zinc-Nickel | Drawing Format | STEP, PDF, Hydraulic Schematic |
Passages That Meet Where the Schematic Says
Faced ports, staged drilling, scoped galleries and a pressure test on every block.
All Galleries Drilled From Machined Faces
Each port face is milled flat before drilling, so the drill does not walk on a scaly surface and the gallery stays within 0.05 mm of its schematic position over a 110 mm depth.
Staged Peck Drilling
Deep galleries are drilled in 3 × diameter pecks with full coolant, which clears chips and keeps the hole straight instead of drifting at the bottom of a 110 mm run.
Bore Scope Before Threading
Every gallery is inspected with a 2 mm bore scope to confirm the cross hole is open and no burr is left at the intersection, before the port threads are cut.
Pressure Tested, Not Sampled
Each block is plugged, filled and held at 350 bar for ten minutes with the test recorded against the serial number, so a leaking block never reaches a customer.
Manifold that has to hold pressure?
Surface Finishes for Manifold Blocks
The outside protects against corrosion; the galleries and threads stay bare and clean.
| Finish | Main Purpose | Finish | Main Purpose |
|---|---|---|---|
| Black Oxide | Oil-retaining corrosion protection | Zinc-Nickel Plating | Salt spray above 500 hours |
| Electroless Nickel | Wear and chemical resistance in galleries | Phosphate | Paint adhesion base |
| Masked Ports | Threads kept bare for fittings | Plug Fitting | Gallery ends sealed before test |
| Laser Marking | Port identification on the block face | Deburr Only | Internal use, no external coating |
| Passivation | Stainless 316 variants | Pressure Test | Every block before packing |
| Gallery Flush | Loose particle removal after plating | Port Caps | Fittings protected in transit |
*Plating inside a Ø6 gallery closes the passage and can flake under pressure; galleries and threads are masked before any coating is applied.
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How We Machine a Manifold Block
Every gallery is drilled from a faced surface and then scoped, so a cross hole that misses by half a millimetre never reaches the test rig.
01. Schematic and Wall Check
Lay the hydraulic schematic over the block drawing, confirm every gallery depth and check the wall thickness at each intersection before the first cut.
02. Square and Mill Port Faces
Face all six sides and mill every port face flat, marking the datum corner and the port map on the top face with a paint pen.
03. Drill Galleries in Stages
Drill each gallery from its port face in peck cycles, alternating drill sizes where a gallery steps down, and clear chips with high-pressure coolant.
04. Deburr and Scope
Deburr every intersection through the ports with a back-chamfer tool, then scope each gallery and photograph the run before threading.
05. Thread, Plug, Test and Finish
Cut the G1/4 and G1/8 threads, plug the gallery ends, pressure test at 350 bar, then black oxide or zinc-nickel with the ports masked.
Send the block drawing with the hydraulic schematic, and we will quote a manifold with the galleries drilled to your circuit and every block pressure tested.
Hydraulic Manifold Block FAQs
Up to 20 × diameter, so 120 mm, with a peck cycle and through-coolant. Beyond that the drill starts to drift and we would rather mill a pocket than drill a curved hole.
Yes. G1/4, G3/8, M14 × 1.5, 9/16-18 UNF and NPT are all cut with the appropriate tap or thread mill, and the thread depth is set from the fitting drawing.
We can fit the plugs we use for testing and leave them in place, or supply the block bare with the plugs in a bag, whichever suits your assembly line.
350 bar for ten minutes as standard, and up to 500 bar on request for steel blocks with a thicker wall. The test record ships with the block.
Yes, in 6082-T6 or 7075-T6 for mobile circuits. The gallery layout stays the same but the wall is increased to 10 mm because aluminium is less forgiving at intersections.
The block is ultrasonically cleaned after threading, blown through each port, and scoped again. The pressure test also flushes any loose particle out through the gauge port.
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