Non-Standard CNC Parts 316L Stainless Steel Turn Mill Manifold Cross Hole 0.01mm Precision

Dongguan Changxinda Precision Technology Co., Ltd. manufactures non-standard CNC parts for industrial buyers who cannot source them from a catalogue. Founded in 2008, the company runs 4-axis and 5-axis machining centers, turn-mill combined CNC lathes and conventional CNC lathes, and exports 50 to 60 percent of production to customers in Europe, North America and the Middle East. Serving industries include medical equipment, robotics, automotive, aerospace, automation, laser, LED, lithium battery and precision testing instruments.

This non-standard CNC part is a stainless steel 316L manifold block or fluid distribution body, produced on a turn-mill combined lathe so that the cylindrical body, the cross drilled flow channels, the threaded ports and the sealing faces are all machined in one set-up. Cross hole intersection is the hard part: the internal burr at the intersection cannot be reached after the block is closed, the sealing face has to be flat enough to hold pressure, and the port threads have to gauge correctly on a part that is already finished on the outside.

One Set-Up Turn-Mill Advantage

Machining a manifold on a machining center and a lathe separately introduces two datum systems and two chances for error. The turn-mill route removes that.

• Billet is gripped once; turning, milling, cross drilling, tapping and face grooving run in the same cycle
• Port position relative to the main bore is generated from one coordinate system, so position tolerance of 0.01 mm holds across all ports
• Concentricity of the sealing face to the bore is held within 0.01 mm, which is what allows an O-ring or a bonded seal to sit correctly
• No re-chucking marks on finished diameters, so no secondary polishing operation is needed
• Cycle is proven on a bar fed lathe for repeat orders, which keeps the per piece time stable

Process Detail for Cross Hole Manifolds

Bar stock and preparation

316L bar stock is certified with heat number and mill certificate. Bars are cut with 1.5 mm facing allowance and the end face is turned square before any feature is cut.

Main bore and port drilling

Main bore is drilled undersize, then bored and reamed to size. Cross holes are drilled with a peck cycle to clear chips at the intersection, then deburred with a back chamfer tool through the bore so the internal edge is broken without leaving a step.

Sealing faces

Sealing faces are turned and then finished to Ra 0.4 mirror finish, flatness within 0.01 mm, with a face groove for the O-ring machined to the drawing width and depth. Surface is checked with a profilometer and, where specified, with a dye penetrant check.

Threads

Port threads are cut with a thread mill rather than a tap for sizes above M8 or G1/4, giving a clean crest and a controlled thread depth. Every port is gauged with go and no-go gauges; BSPP and NPT threads are gauged to the relevant standard.

Cleaning and testing

Parts are degreased, ultrasonically cleaned and passivated. On request we pressure test at 1.5 times working pressure and issue a test record with the batch.

Non-Standard Manufacturing Service

• Drawings accepted in STEP, IGES, X_T, DWG, DXF or PDF, or a sample part for reverse engineering
• Prototype quantity from 1 piece, no tooling cost, no minimum order quantity
• Materials: 316L, 304, 303, 17-4PH stainless steel, plus brass, aluminum and carbon steel on request
• Thread standards: metric, BSPP, BSPT, NPT, UNF, custom
• Finishes: passivation, electropolishing, mirror polish, nickel plating, glass bead blasting
• Assembly: O-rings, bonded seals, plugs and fittings installed and leak checked in house

Precision and Quality Control

• Dimensional tolerance plus or minus 0.01 mm on bore, port position and sealing face
• Surface roughness Ra 0.4 on sealing faces, Ra 0.8 on turned diameters
• CMM and optical comparator inspection, thread gauges for every port
• Material certificate with heat number, dimensional report, first article report for new parts
• Traceability from bar stock heat number to finished batch, retained for 3 years

Delivery Reliability

Turn-mill parts run on dedicated lathes with proven programs, so the production time is predictable rather than re-estimated each order.

• Prototype and sample quantities: 3 to 7 working days
• Batch of 10 to 200 pieces: 7 to 15 working days
• Repeat orders with scheduled call offs: reserved machine capacity, fixed lead time
• Weekly progress report, and a written notice at least 5 working days ahead if a date is at risk
• Shipping by express, air or sea, door to door, with packing that protects finished sealing faces

Frequently Asked Questions

Can you guarantee the internal burr at the cross hole intersection is removed?

Yes. We use a back chamfer or deburring tool through the main bore after cross drilling, and the bore is inspected with a borescope on first article. If the channel geometry blocks access, we propose a design change during DFM review.

Which thread standards can you machine?

Metric, BSPP, BSPT, NPT, UNF and custom profiles. Please state the standard on the drawing, since a G1/4 and an NPT 1/4 are not interchangeable.

Do you pressure test?

Yes, on request at 1.5 times working pressure with a written test record. Tell us the test pressure and medium when you send the drawing.

What is the smallest order you accept?

One piece. Prototypes are a normal part of our workload, not an exception.