Custom Precision Brass CNC Turned Parts
Overview
XCM CNC provides brass CNC turning for rotational parts such as connector pins, valve stems, sleeves, bushings and threaded fittings. Assembly depends on the coaxial relationship between outside diameters, bores, end faces and threads. Precision mating features on parts under 100 mm can achieve +/-0.003 mm; large parts can be turned up to 1250 mm in diameter and 2000 mm long. The factory is certified to ISO 9001, ISO 13485, IATF 16949 and GJB9001C. The MOQ is 1 piece, with samples in 3-7 days and batches usually in 10-15 days. For a quote, provide 2D/3D drawings, the grade and quantity, and identify fit tolerances, thread standards, roughness and plating requirements.
Key Capabilities
- Materials: C36000, C35300, C46400, C26000 (H59 / H62); other brass grades by drawing
- Tolerance: +/-0.003 mm (+/-0.00012 inch), IT5 or IT6 accuracy, +/-0.01 mm shaft/bore fits; h6/H7 available
- Surface Finish: Turned OD Ra 0.8 um; bored and reamed holes Ra 1.6 um; honed bores Ra 0.8 um (by bore diameter and length); polished Ra 0.2 um; precision polishing on critical areas down to Ra 0.015 um (selected features, by drawing review)
- GD&T: Coaxiality 0.012 mm; roundness 0.006 mm; circular and end-face runout 0.012 mm; cylindricity 0.011 mm / 1030 mm; straightness 0.01 mm / 1030 mm
- Max Size: Turning diameter 1250 mm x 2000 mm length (diameter 1200 mm conservative); bore up to 1000 mm, depending on equipment travel and setup
- Surface Treatment: Nickel / chrome plating 3-20 um; polishing (mirror, bright, matte); sand blasting 80#-220#; depending on drawing and order requirements
- Thread: Internal M1.4-M220, external from M2.0; thread depth 4 x D; NPT / BSP / G / PT pipe threads; go/no-go gauge or ring gauge inspection
- Precision Limit: +/-0.003 mm on precision features of parts under 100 mm, roundness 0.006 mm, coaxiality 0.012 mm (specific features, by drawing review)
Brass Long Shaft and Large-Diameter Turning Capacity
Brass rotational parts can be turned to a diameter of 1250 mm at a length of 2000 mm on the Shenyang CK61125X2000 lathe. Slender shafts can reach a length-to-diameter ratio of 15:1. The straightness capability of 0.01 mm / 1030 mm is stated over a 1030 mm reference length. Circular runout of 0.012 mm requires a defined inspection datum and setup. For higher length-to-diameter ratios, shaft diameter and length determine whether a steady rest or follower rest is needed and whether machining should be split into separate operations.
Brass Turned Threads from M1.4 to M220 with Gauge Check
Brass turned internal threads start at M1.4 and external threads at M2.0, with a maximum size of M220. Thread depth can reach 4 x D, with an effective blind-hole thread depth of 50 mm and at least 0.3 mm of stock at the blind-hole bottom. Specify NPT, BSP, G or PT pipe thread standards on the drawing. Functional threads are checked with go/no-go or ring gauges. Brass is relatively soft, and damage at thread entrances can affect gauging and assembly. Requirements for crossed or damaged threads, burrs, impact marks and scratches can be stated directly on the drawing.
Brass Bore Fits and Roughness on Turned Sleeves and Bushings
Brass bores can be controlled to H7 / H8 or +/-0.006 mm, with bored and reamed surface roughness of Ra 1.6 um. Where hydraulic or sliding bores need smoother surfaces, honing can achieve Ra 0.8 um, subject to bore diameter and length. The maximum boring diameter is 1000 mm, depending on equipment travel and setup. Deep holes support L/D = 10; higher ratios require evaluation for deep-hole drilling or special processes.
Brass Turned Grooves, O-Ring Seats and Knurling
Turned grooves have a minimum width of 0.5 mm. O-ring grooves have a minimum width of 1.0 mm and a depth tolerance of 0.01 mm; the customer’s sealing design determines the O-ring size and groove geometry. Chamfers range from C0.1 to C3.0 mm, and parts handled by hand can have sharp edges broken by 0.1 mm. Straight and diamond knurling are available with modules of 0.3-1.0.
Specifications
| Product Name | Custom Precision Brass CNC Turned Parts |
|---|---|
| Manufacturer | XCM CNC (Shenzhen Xinchuangmeng Co., Ltd) |
| Factory Location | Shenzhen, Guangdong, China |
| Quality System | ISO 9001, ISO 13485, IATF 16949, GJB9001C |
| Machining Process | CNC turning |
| Material Grade | C36000, C35300, C46400, C26000 (H59 / H62); other grades specified on the drawing |
| Tolerance | +/-0.003 mm on precision features of parts under 100 mm; IT5 / IT6; shaft h6 / h7 or +/-0.005 mm; bore H7 / H8 or +/-0.006 mm |
| Surface Roughness | Turned OD Ra 0.8 um; bored / reamed Ra 1.6 um; honed Ra 0.8 um (by bore diameter and length); polished Ra 0.2 um; critical-area polishing Ra 0.015 um (selected features) |
| Surface Treatment | Nickel / chrome plating 3-20 um, polishing, sand blasting 80#-220#; type, thickness and masking depending on drawing and order requirements |
| Max Part Size | Turning diameter 1250 mm x length 2000 mm (diameter 1200 mm conservative); slender shaft L/D 15:1 |
| Application | Connector pins, valve stems, guide shafts, sleeves and bushings, sensor and pneumatic fittings, knurled knobs |
| Key Features | Coaxial turned diameters, bores, shoulders, grooves, O-ring seats, knurling and threads (internal M1.4-M220, external from M2.0; NPT / BSP / G / PT) |
| Critical QC Requirements | Rotational datum, mating fits, runout method, thread standard with go/no-go or ring gauge, burr limits and report scope |
| MOQ | 1 piece |
| Typical Lead Time | Samples 3-7 days; standard 10-15 days depending on complexity and quantity |
| Drawing Formats | STEP, IGES, STP, DWG, PDF with dimensions |
| Critical Tolerance Control | Coaxiality 0.012 mm; roundness 0.006 mm; circular runout 0.012 mm; end-face runout 0.012 mm; cylindricity 0.011 mm / 1030 mm; straightness 0.01 mm / 1030 mm |
Applications
Connector Pins and Contacts
Connector pins and contacts mate with sockets through their outside diameters, shoulders and end geometry. Inconsistent coaxiality can affect insertion and electrical contact. Brass is readily machinable and electrically conductive, making it a common material for these small electrical parts; grade and plating depend on electrical operating conditions. Small-diameter mating features can be controlled to h6 / h7 or +/-0.005 mm, with +/-0.003 mm evaluated for precision features on parts under 100 mm.
Valve Stems and Guide Shafts
Sealing areas, guide sections and threaded ends on valve stems and guide shafts share a common axis. Straightness and coaxiality between stepped outside diameters directly affect smooth operation. Shaft diameter tolerances and roughness at sealing areas must be evaluated together. Turned outside diameters can achieve Ra 0.8 um, and O-ring and retaining-ring grooves can be machined on the same shaft. The customer defines media and working pressure according to operating conditions.
Sleeves and Bushings
Locating sleeves and plain bushings mate through their bores, outside diameters and end faces. Misalignment can prevent housing assembly or cause shafts to bind. H7 / H8 bore fits and coaxiality and face runout capabilities of 0.012 mm suit these parts. Thin-wall sleeves can distort during clamping, so wall thickness and clamping methods must be established before machining.
Sensor and Pneumatic Fittings
Sensor threaded fittings and pneumatic fittings combine threads, sealing end faces and through-holes. External threads on small sensor parts can be as small as M2.0. Pipe threads follow NPT, BSP, G or PT standards and are checked with go/no-go gauges. The customer’s interface design determines whether the sealing end uses an O-ring groove or a flat seal. Media, pressure and leak-testing requirements must be provided by the customer according to operating conditions.
Knobs and Knurled Parts
Knurled nuts and knobs use textured surfaces for grip, with feel determined by knurl type and module. Hand-contact edges can be broken by 0.1 mm. Cosmetic surfaces can receive mirror, bright or matte polishing, with appearance requirements defined by drawings or approved samples.
Why Choose Us
Quality Systems and Turning Equipment
The factory is certified to ISO 9001, ISO 13485, IATF 16949 and GJB9001C, with machining equipment from DMG, Mazak, Matsuura and Brother. Brass turning is supported by the Mazak I-100S turn-mill center, Jingshang 80 automatic lathe and Shenyang CK61125X2000 large lathe. Inspection uses measuring equipment including Hexagon CMMs.
Turning Coverage from Pins to Large-Diameter Parts
Our machining coverage extends from small connectors to large structural parts. Brass turned parts range from connector pins and locating pins to rotational parts 1250 mm in diameter and 2000 mm long. Holes, threads, grooves and knurling can be quoted together.
Matching Equipment to Accuracy to Control Turning Costs
Our CNC equipment spans four tiers from mainland China, Taiwan, Japan, and Europe and the United States. Machines are matched to the accuracy required by each part and operation to balance machining quality and cost. Small precision pins and sleeves have different accuracy and size requirements from large-diameter long shafts, and each is assigned suitable equipment.
Inspection Documents according to Order Requirements
Brass turned parts can include dimensional inspection reports according to order requirements, covering critical dimensions such as shaft diameters, bore diameters and runout. Threads are checked with go/no-go or ring gauges. Specify any requirements for material certificates, SGS environmental compliance reports or FAI reports in the customer’s format when ordering.
Plating Thickness Considered Together with Mating Dimensions
Brass turned parts often require nickel or chrome plating. Coating thicknesses of 3-20 um change outside diameters, bores and thread dimensions. Before machining, we account for coating effects on mating surfaces, threads and O-ring grooves. The order specifies whether acceptance dimensions apply before or after plating and which areas require masking.
FAQ
Does +/-0.003 mm apply to every diameter on a turned brass part?
No. +/-0.003 mm applies to precision features or mating surfaces on parts under 100 mm and depends on inspection methods and batch consistency. Parts over 500 mm are generally evaluated using a large-part tolerance of +/-0.05 mm. Parts between 100-500 mm, along with h6 / h7 shaft fits and H7 / H8 bore fits, are reviewed individually against the tolerance grades specified on the drawing.
Should I specify concentricity or runout on a brass turned part?
Concentricity and runout control different geometric characteristics and are not interchangeable. Select the control required by the drawing standard and the function of the part. Our stated coaxiality and shaft circular runout capabilities are both 0.012 mm. Define the datum, tolerance and inspection method on the drawing so the machining setup can be reviewed.
What should the drawing show for an O-ring groove on a brass part?
Specify groove width, depth and depth tolerance, roughness on the groove bottom and sidewalls, and burr requirements. The minimum O-ring groove width is 1.0 mm, with a depth tolerance of 0.01 mm. Your sealing design determines O-ring size, compression and sealing performance.
How thin can the wall of a turned brass sleeve be?
The minimum metal wall thickness is 0.5 mm. Blank pretreatment, stress-relief aging and optimized machining parameters are needed to control thin-wall distortion. Clamping distortion becomes more pronounced as sleeves become thinner and longer, so provide the clamping approach and inspection datums together.
Which brass grade suits turned parts with lead-free or environmental requirements?
C36000 is a leaded free-cutting brass commonly used for batch-turned pins, sleeves and fittings. State any lead-free or environmental requirements, plating needs or drinking-water contact in your inquiry so the grade can be reviewed accordingly. Material certificates and SGS environmental compliance reports can be provided according to order requirements.
Can critical dimensions on small turned brass parts be 100% inspected?
Yes. Critical dimensions and appearance can receive 100% inspection. The drawing and order define the items and scope, such as mating outside diameters, bores or thread go/no-go checks. Results can be included in the dimensional inspection report.
Is a 3D model enough to quote a turned brass part, or can I send a sample?
Usually not. A 3D model defines geometry, but tolerances, fit grades, thread standards, roughness and material grade need a 2D drawing or dimensioned PDF. A quote requires drawings, grade, tolerances, quantity and intended use; supported formats include STEP, IGES, STP and DWG. Parts can also be machined from samples when drawings are unavailable. Provide critical dimensions and tolerances with the sample to reduce measurement-related errors.
Request a CNC Machining Quote from XCM CNC
Send us your drawings. Our team will review the file and reply with a machining quote. MOQ: 1 piece, with competitive low-cost pricing.
