Precision Turned 4140 Alloy Steel Hydraulic Manifold Sleeve HRC 32 Zinc Nickel Plated

This hydraulic manifold sleeve is machined from Alloy Steel 4140 (4140 quenched and tempered) to ±0.01mm in the critical dimensions, then finished by Zinc nickel plated 8μm. It is produced on CNC turning centres that are dedicated to small and medium volume precision work, so every dimension on the drawing is generated by the machine rather than by hand fitting. Typical users are engineers who have already been let down by a supplier that quoted a tolerance it could not hold, and who need the part to fit the first time without sorting or rework on the assembly line.

• High Pressure Wall: 4140 at HRC 30-34 provides the hoop strength needed for 350 bar service with a 5mm wall
• Zinc Nickel Corrosion Protection: Zinc nickel plating gives over 720 hours salt spray resistance without hydrogen embrittlement risk
• Bore Honed To H7: Bore is honed after hardening so the spool clearance stays in the specified window
• Cored Oil Passages: Cross drilled passages are deburred and flow checked so pressure drop stays predictable
• Threaded Ports Gauge Verified: Port threads are checked with system gauges to the SAE or BSP standard you specify

The process route is fixed before metal is cut. Bar stock is verified against the purchase specification and the heat number is logged, then a first article is turned and measured in full. Only after the first article is signed off does the lot run. Critical features on this hydraulic manifold sleeve are controlled to ±0.01mm with a process capability target of Cpk 1.33 or better, and the operator checks the feature at a defined frequency with the gauge stated on the control plan. Where the drawing calls for Zinc nickel plated 8μm, the finishing step is carried out in house and the result is measured, not assumed. Sample parts go to the CMM for full dimensional verification, and the recorded results ship with the lot as a first article inspection report in PPAP level 3 format when a customer program requires it.

Questions are handled by engineers rather than by sales staff. Our team reviews each drawing for manufacturability, flags features that would drive cost without adding function, and proposes the tolerance band that actually matters for the assembly. That review is free and is returned within 24 hours together with a quotation. When a part fails in the field, we ask for the sample back, section it if needed and report what the failure mechanism was, because a supplier that cannot explain a failure cannot prevent the next one.

• Machines: 50+ CNC units including Swiss type lathes, 3, 4 and 5 axis machining centres and turn-mill centres from Citizen, Star, Doosan and Mazak.
• Quality lab: CMM, 2D vision measurement, roughness tester, hardness tester, salt spray chamber and spectral analyser for material verification.
• Team: 15+ mechanical engineers covering DFM review, process design, fixture design and failure analysis.
• Capacity: 500,000+ precision turned parts per month with stable output and on time delivery tracking.
• Quality system: ISO 9001:2015 certified, SGS audited, material traceability from mill heat to finished part.
• Export experience: parts shipped to 30+ countries across North America, Europe, Japan, Korea and Southeast Asia.

Hydraulic valve blocks, cylinder end caps, pressure test manifolds, and mobile hydraulics distribution sleeves.

Parts are degreased, dried and packed so that the surface finish specified above arrives intact. Standard packing is VCI paper or individual PE bag, a partitioned foam tray for form features, and an export grade corrugated carton on a pallet, with the lot number and heat number marked on the outside. Parts are warranted against material and workmanship defects for 12 months from delivery. If a part is found outside the drawing, we replace it at our cost and we pay the return freight for the defective lot. Third party inspection by SGS, BV or TUV can be arranged before shipment at your request, and we work under NDA where drawings are confidential.

Q: Is zinc nickel plating safe for high strength steel? A: It is the preferred choice. Zinc nickel can be applied with low hydrogen embrittlement processes and is baked after plating. We specify the bake cycle in the process sheet.

Q: Do you hone the bore after heat treat? A: Yes. Hardening distorts the bore, so honing is the only way to hold H7 and the required surface finish of Ra 0.4μm.

Q: Can you proof test the sleeve? A: We can hydrostatic proof test to 1.5 times working pressure on samples, and 100 percent if your program requires it.

Q: What documentation comes with a pressure containing part? A: Material certificate, heat treat record, plating certificate, dimensional report and proof test results if applicable.

Q: How do you confirm the Alloy Steel 4140 material before it is machined? A: Every bar is checked against its mill certificate with an optical emission spectrometer before it goes to a machine. If the chemistry does not match the grade, the bar is rejected and returned. The certificate for your lot is filed under the heat number and can be sent with the shipment or on request.

Q: What happens if a delivered part measures outside the ±0.01mm tolerance? A: Send the measurement and the lot number. We check the recorded values for that lot, replace the parts at our cost and cover the return freight. Because each critical feature is recorded during production, we can trace the deviation to a tool wear step, a fixture shift or a gauge issue and correct the process before the next lot runs.

Send a 2D drawing, a STEP file or a sample and you will have a manufacturability review and a firm quotation within 24 hours. Trial orders from a single piece are accepted, so the tolerance claim can be checked on your own assembly before a production order is placed.