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Customer: Global Industrial Automation & Fluid Control Manufacturer
Product: Precision Machined Brass Tube Fittings / Threaded Hose Connectors
Material: C36000 Free-Cutting Brass
Process: Swiss CNC Machining + Precision Turning + Thread Rolling
Challenge: Deliver leak-proof brass hydraulic fittings and brass fittings for air lines with ±0.01 mm tolerance on sealing surfaces, supporting BSP, NPT, and metric custom threads across prototype to medium batch volumes (1,000 – 50,000 pcs/month).
Solution: Multi‑axis Swiss machining with thread rolling + 100% thread gauge inspection + optional nickel plating.
Result: 99.6% first-pass yield, zero leakage in pressure cycle tests, scalable from prototype to 50,000 pcs/month.
For more details on our precision manufacturing capabilities, explore our Swiss Machining Services.
One of the world's largest manufacturers of fluid transfer systems and pneumatic controls wanted to find a way to get precision brass tube fittings and threaded hose connectors from one source. Their product line included brass water tube fittings for HVAC applications, brass hydraulic fittings for low-pressure hydraulic systems, brass fuel line connectors for automotive applications, and brass gas line fittings for industrial gas distribution. In addition, the customer needed to be able to get chrome-plated brass tubing options and an anti-oxidation treatment on their brass tubing to protect it against sea environments (marine grade brass tubing).
From our long history of producing forged brass fittings and cast brass components, we have found that combining Swiss-style CNC Machining with Thread Rolling provides the best way to achieve the required ±0.01 mm tolerances on critical sealing areas. We can also accommodate prototype runs (typically 7-15 days) and large scale (20-30 days) mass production, with volume multiples from 1,000 to 100,000 pcs. for every month. The project leveraged our expertise in Swiss Machined Components and Connectors and Fittings.
| Parameter | Specification |
| Product Type | Brass Tube Fittings / Threaded Hose Connectors |
| Material | C36000 Free-Cutting Brass (High machinability grade) |
| Manufacturing Process | Swiss CNC Machining + Precision Turning + Thread Rolling |
| Thread Standard | BSP / NPT / Metric Custom Threads |
| Surface Finish | Natural brass / Optional nickel plating / Anti-oxidation treatment |
| Tolerance | ±0.01 mm for critical sealing and thread engagement areas |
| Application | Fluid transfer systems, pneumatic lines, hydraulic low-pressure systems |
| Key Performance Requirements | Leak-proof sealing, high thread engagement accuracy, corrosion resistance |
| Production Volume | Prototype → Medium batch (1,000 – 50,000 pcs/month scalable) |
| Quality Inspection | 100% thread gauge inspection + dimensional CMM sampling |
| Lead Time | 7–15 days for prototypes, 20–30 days for mass production |
| Industry Use | Automotive, HVAC systems, industrial automation, plumbing systems |
The customer previously sourced industrial grade brass fittings from multiple suppliers but faced three specifically major problems. These include inconsistent thread sealing performance under pressure cycles wherein some brass hydraulic fittings leaked at rated pressure, system downtime, and poor concentricity between the inner bore and external threads on brass water tube fittings. This led to uneven flow and accelerated wear. Lastly, no single supplied end line could handle forged brass fittings that offered strength and complex-shaped cast brass components while providing chrome plated brass tubing for decorative corrosion protection.
Specifically, they required heavy duty brass fittings that could withstand vibration in automotive fuel lines, brass fittings for air lines in industrial automation, gas line brass fittings for natural gas systems, and HVAC brass tubing parts with anti‑oxidation treatment. The customer also expected full traceability in compliance with ISO 9001, including the ability to scale from prototype (200 pcs) to medium batch volumes (50,000 pcs), without the need for requalification. Our solution integrated Swiss machining with thread rolling, taking advantage of C36000 brass's superb machinability and anti-seizing characteristics.
Material receiving: C36000 free‑cutting brass bar stock (certified, with traceability).
Swiss CNC machining:
Guide bushing support ensures tight concentricity between inner bore and external threads.
Main spindle: O.D. and I.D. roughing/finishing, chamfering, and grooving for O‑ring seats.
Thread rolling (rather than cutting) for BSP, NPT, or metric threads – work‑hardens thread flanks for higher fatigue strength and anti‑seizing performance.
Live tooling for cross holes, hex flats, and orientation flats.
Secondary operations:
Optional nickel plating or anti‑oxidation treatment for chrome plated brass tubing appearance and corrosion resistance.
Ultrasonic cleaning to remove all cutting fluids and debris from internal passages.
100% thread gauge inspection: Automated go/no‑go gauging for all thread standards.
CMM sampling: First article and periodic sampling (every 50 pcs) for full dimensional verification including concentricity, perpendicularity, and surface finish.
Leak testing on samples: Pressure decay test at 1.5x working pressure to validate sealing performance.
Laser marking: UID traceability for each batch.
Our advanced Brass and Copper Machining capabilities ensure consistent quality across all production volumes.
C36000 brass is easy to machine, yet high-speed cutting thermally expands and results in dimensional drift from that heat. The answer is to implement a probe inspection system with automatic tool wear compensation during the machining process. Additionally, using thread rolling (not cutting) will also reduce pitch diameter variation.
Airline fittings will not maintain an absolute seal at fast pressure cycling (0 to 150 psi's for 10,000 cycles). The solution was that using thread rolling made a much smoother and more consistent thread profile than if cut. Additionally, to the cleaned-up threads, a very small amount of customer-specified PTFE sealant was used.
Poor Concentricity (over 0.02mm) would contribute to non-uniform wall thicknesses and possible leak paths. The solution was to use single-set-up Swiss machining with a guide bushing in order to eliminate re-fixturing errors. Concentricity less than 0.01mm was consistently attained.
Standard brass has been shown to corrode at a rapid rate in the marine atmosphere (i.e., being exposed to salt water mist). By applying a proprietary chromate-free anti-oxidation treatment and/or nickel plating, this issue has been resolved. The result was compliance with ASTM B117 of the 500-hour salt spray test.
Early prototype tooling wasn't built to run volumes at speed; we developed modular tooling to use the same set of pilot plates and minuscule machine adjustment time significantly decreased production lead time and changeover time from (90 min.) down (12 min.). Additionally, a second shift and automated bar feed tooling enabled lights-out production.
All brass tube fittings that are machined accurately will have a multi-stage QC Plan to ensure compliance with the requirements of ISO 9001:2015. The In-Process checks will include the use of a CNC Probe to measure critical diameters (every 10 Parts). A 100% inspection of threads will be performed by the use of automated gauges on both BSP and NPT threads, Any Part that fails either the go or no-go thread gauges will be automatically denied. A CMM will be used to sample all production to measure concentricity, perpendicularity, pitch diameter of threads, and surface finish per Ra ≤ 0.8 μm of the sealing face. When plating brass tubing a test of adhesion will be completed in accordance to ASTM B571. Statistical samples to measure pressure decay leak testing will be performed on all Brass tube fittings at AQL 0.65 at 1.5X rated pressure. All Lot traceability data will be retained for 10 years.
| Metric | Target | Achieved |
| First‑pass yield | ≥95% | 99.6% (over 350,000 parts delivered) |
| Thread gauge rejection rate | <1% | 0.3% (all reworked) |
| Concentricity (bore to thread) CpK | ≥1.33 | 1.58 |
| Leak test failure rate (sample) | <0.5% | 0.05% |
| On‑time delivery | 98% | 99.70% |
| Customer field failure (12 months) | ≤50 ppm | 0 ppm |
| Lead time reduction vs. previous supplier | – | -35% |
The client has increased its range of products by adding brass connectors used in hydraulics; brass fittings for compressed air circuits in mining equipment; and brass connectors used to join fuel lines in vehicles intended for use on undeveloped land. All new items are produced using the same manufacturing process.
This manufacturing capability serves diverse industries requiring precision brass tube fittings and threaded hose connectors:
Automotive: Fuel line brass connectors for carburetors, brake line fittings, coolant hose adapters.
HVAC systems: Brass water tube fittings for chillers, condensers, and air handling units – including HVAC brass tubing parts with anti‑oxidation treatment.
Industrial automation: Brass fittings for air lines in pneumatic actuators, valves, and cylinders.
Plumbing systems: Cast brass components for faucets, valves, and water meters; forged brass fittings for high‑pressure water lines.
Marine: Marine grade brass tubing for seawater cooling systems, deck wash fittings, and bilge pumps – with chrome plated brass tubing for exposed areas.
Gas distribution: Gas line brass fittings for natural gas and propane regulators, meters, and appliance connectors.
Low‑pressure hydraulic systems: Brass hydraulic fittings for lubrication lines, log splitters, and agricultural equipment.
Beyond precision machined brass tube fittings, we offer complete solutions for brass components:
Swiss CNC machining of C36000, C46400, C48500, and other brass alloys.
Precision turning and thread rolling for BSP, NPT, metric, and custom threads.
Forged brass fittings and cast brass components for high‑strength applications.
Chrome plated brass tubing and nickel plating for corrosion protection and aesthetics.
Heavy duty brass fittings with extra wall thickness for high‑pressure or vibration‑prone systems.
Brass fittings for air lines, water tube, hydraulic, fuel, and gas lines – full application coverage.
Anti‑oxidation treatment for marine grade brass tubing and outdoor equipment.
Prototyping and medium batch production (1,000 – 50,000 pcs/month) with fast lead times.
Our engineering team supports OEM customers with DFM analysis, material selection (including lead‑free alternatives), and PPAP level 3 documentation.
Ready to source precision machined brass tube fittings or threaded hose connectors for your fluid or pneumatic system? Submit your CAD model (STEP, IGES) and thread specification.
We will respond within 24 hours with:
DFM analysis for concentricity, thread rolling feasibility, and surface treatment.
Prototype pricing and lead time (7–15 days for 100–500 pcs).
Volume pricing for 1,000 – 50,000 pcs/month.
Sample first‑article inspection report with CMM and thread data (free).
Email: quote@falconcncswiss.com or contact us directly today
