Custom Precision Brass CNC Milled Parts
Overview
XCM CNC provides brass CNC milling for prismatic parts with pockets, narrow slots and hole patterns, including terminal plates, connector mounting plates, small valve blocks and instrument brackets. Brass is readily machinable and commonly used for parts requiring conductive connections. Milled mounting faces and hole locations must align with mating parts, so datum faces and hole-pattern relationships are a key part of quotation review. 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, quantity, critical tolerances and intended use. Identify hole spacing, datum faces and plating requirements as well.
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: Standard milled Ra 3.2 um; fine-milled Ra 1.6 um; lapped Ra 0.4 um (selected faces); precision polishing on critical areas down to Ra 0.015 um (selected features, by drawing review)
- GD&T: Flatness 0.02 mm (faces up to 1030 x 1030 mm); parallelism 0.03 mm / 1030 mm; perpendicularity 0.02 mm / 1000 mm; hole position 0.015 mm (hole groups, locating and mounting holes)
- Max Size: 3-axis milling travel 3000 x 1600 x 1400 mm; workpiece length up to about 2600 mm, depending on fixturing 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 from M1.4, external from M2.0, up to M220; thread depth 4 x D; NPT / BSP / G / PT pipe threads; go/no-go gauge inspection
- Precision Limit: Flatness 0.02 mm; metal walls down to 0.5 mm with blank pretreatment and stress relief; slots from 0.3 mm wide
Brass Pocket and Slot Milling with Depth-to-Width Limits
The machining difficulty of pockets and narrow slots in brass plates depends mainly on depth-to-width ratio. Cavities support a ratio of 4:1, extending to 5:1 with long-reach tools. Minimum slot width is 0.3 mm; at a width of 25 mm, maximum slot depth is 100 mm. Tool rigidity and chip evacuation become more important as slots get narrower and deeper. Metal walls can be as thin as 0.5 mm, but blank pretreatment, stress-relief aging and optimized machining parameters are needed to prevent distortion. Identify thin pocket-wall locations and thicknesses on the drawing.
Brass Flat Faces and Datum Relations on Milled Plates
Mounting and datum faces determine the assembly relationships of terminal plates and connector flange plates. Flatness of 0.02 mm applies to a maximum machined area of 1030 x 1030 mm, with parallelism of 0.03 mm / 1030 mm and perpendicularity of 0.02 mm / 1000 mm. Feasibility depends on datum selection, clamping and inspection methods; large or thin-wall plates require drawing-based evaluation. Define the primary datum first, then dimension faces and hole locations from the same datum.
Brass Hole Groups, Tapped Holes and Cross-Drilled Passages
Hole-group position in brass blocks can be evaluated at 0.015 mm, depending on hole diameter, spacing, count and inspection method. Minimum drilled hole diameter is 0.2 mm and minimum milled hole diameter is 0.3 mm. Axial deep holes support L/D = 10. Internal threads start at M1.4, with an effective blind-hole thread depth of 50 mm and 0.3 mm of stock required at the bottom. Cross-holes can be deburred, and minimum internal passage width is 3.0 mm. Cleaning and leak-testing requirements need separate agreement.
Brass Milled Surface Finish by Function
Standard milled surfaces are Ra 3.2 um, while mounting and contact faces can be fine milled to Ra 1.6 um. Sealing or precision datum faces can be lapped to Ra 0.4 um where a smoother surface is needed, with suitability evaluated against size and flatness requirements. Nickel or chrome plating thicknesses of 3-20 um change bore diameters, slot widths and thread dimensions. Specify on the drawing whether acceptance dimensions apply before or after plating.
Specifications
| Product Name | Custom Precision Brass CNC Milled 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 milling |
| Material | Brass |
| 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 on specified features; bore H7 / H8 or +/-0.006 mm; +/-0.05 mm for parts over 500 mm |
| Surface Roughness | Milled Ra 3.2 um; fine-milled Ra 1.6 um; lapped Ra 0.4 um (selected faces) |
| 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 | Workpiece length up to about 2600 mm, depending on fixturing and setup |
| Application | Electrical terminal plates, RF connector flange plates, compact valve and pneumatic blocks, instrument and sensor brackets |
| Key Features | Prismatic plates and blocks with pockets, slots, hole groups, tapped holes (internal from M1.4, external from M2.0, up to M220) and cross-drilled passages |
| Critical QC Requirements | Primary datum, hole-group position, flatness, plating allowance, burr limits and passage cleaning; CMM or dimensional inspection, thread go/no-go gauges and report scope as agreed in the order |
| 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 | Flatness 0.02 mm (faces up to 1030 x 1030 mm); parallelism 0.03 mm / 1030 mm; perpendicularity 0.02 mm / 1000 mm; hole position 0.015 mm |
Applications
Electrical Terminal Blocks and Terminal Plates
Terminal block bases and terminal plates require milled mounting faces, fixing slots and grouped holes to align with insulating bases and conductors. Brass is readily machinable and electrically conductive, making it suitable for these connection plates. Grade, coating and electrical requirements depend on drawings and operating conditions. Hole-group position can be evaluated at 0.015 mm.
RF Connector Flange Plates
RF connector flange plates and shield assembly plates require connector hole locations to relate to the mounting datum. Mounting faces, recessed seats and hole patterns can be milled into the same plate. Countersunk screw holes have a cone angle of 90 degrees with a tolerance of +/-0.1 degrees. Hole locations and surface treatment depend on mating-part requirements.
Small Valve and Pneumatic Blocks with Orthogonal Ports
When ports on valve blocks and pneumatic manifold blocks are orthogonal, milling can produce the mounting faces, pockets and cross-holes. Specify cross-hole burr limits and internal cleanliness requirements in the order. Leak or pressure testing requires separate agreement.
Instrument and Sensor Mounting Brackets
Pockets, weight-reduction slots and mounting holes on instrument brackets and sensor mounting brackets are arranged around planar datums. Perpendicularity between mounting and datum faces affects sensor position and can be evaluated at 0.02 mm / 1000 mm. Brass selection depends on conductivity, grounding or machinability requirements.
Why Choose Us
Quality Systems and Milling Equipment
The factory is certified to ISO 9001, ISO 13485, IATF 16949 and GJB9001C, with machining equipment from DMG, Mazak, Matsuura and Brother. Brass plates and blocks are milled on machining centers from Brother, Taichung and Qiao Feng. The Qiao Feng machine has 3-axis travel of 3000 x 1600 x 1400 mm.
Milling Coverage from Small Terminal Plates to Large Plates
Our machining coverage extends from small connectors to large structural parts. Pockets, narrow slots, hole patterns and tapped holes in brass plates can be quoted together. Where plating, polishing or sand blasting is needed, treatment type and masking areas depend on order requirements.
Matching Equipment to Accuracy to Control Milling 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. Within the same batch of brass milled parts, precision hole locations and general mounting faces have different requirements and receive equipment suited to their accuracy needs.
Inspection Documents according to Order Requirements
Brass milled parts can include CMM and FAI reports according to order requirements, with FAI reports available in the customer’s format. Specify any requirements for material certificates or SGS environmental compliance reports when ordering. Critical dimensions and appearance can receive 100% inspection, with the scope defined by drawings and the order. Inspection methods for geometric tolerances such as flatness and position must be established first.
Sample Approval before Batch Production, with NDA Support
Samples are usually delivered in 3-7 days, and customer sample approval is required before batch production. An NDA can be signed as needed for projects involving unpublished designs.
FAQ
How should datums be defined for a brass milled hole pattern?
Define the primary datum face according to the assembly relationship, then specify hole-group position relative to that datum. Hole-group position capability is 0.015 mm, depending on hole diameter, spacing, count and inspection method. If the pattern must relate to features on the opposite side, show how the datum is transferred so the setup and inspection plan can be evaluated.
What internal corner radius should I allow in a milled brass pocket?
Use R0.5 mm for standard internal corners, reflecting the end mill limit. For cavities 40 mm deep, R1.0 mm is recommended; greater depth generally requires a larger internal corner radius. Perfectly sharp internal corners require EDM or a design adjustment.
Can cross-drilled passages in a brass block be deburred and cleaned?
Cross-holes can be deburred, with a minimum internal passage width of 3.0 mm. State internal burr-control and cleanliness standards on the drawing or in the order. Leak testing, pressure testing and plug arrangements must be listed separately with an agreed scope. Deburring alone does not constitute functional testing.
Does +/-0.003 mm or IT5 / IT6 apply to the whole milled brass part?
These values do not apply universally to the whole part. +/-0.003 mm is used for precision features or critical dimensions on parts under 100 mm, subject to inspection methods and batch consistency. IT5 / IT6 is planned for specified features, and some dimensions require secondary operations such as grinding, EDM or wire EDM. Identify the target features, datums and inspection requirements on the drawing.
How do I specify brass grade and plating for a conductive part?
State the brass grade and applicable standard in the drawing or inquiry, describe the conductive function, and specify coating type, thickness and masking areas. Different grades should not be treated as equivalent based only on their names. Coatings of 3-20 um change dimensions, so the order must define whether acceptance applies before or after plating.
How large a brass plate can be milled, and how are large parts toleranced?
Three-axis milling travel is 3000 x 1600 x 1400 mm, with workpiece lengths of about 2600 mm depending on fixtures and setup. Parts over 500 mm are generally evaluated using a large-part tolerance of +/-0.05 mm. Flatness of 0.02 mm applies to a maximum area of 1030 x 1030 mm. Larger or thinner plates require evaluation against the drawing.
What do you need to quote a brass milled part, and how soon can samples be made?
Provide 2D/3D drawings in STEP, IGES, STP or DWG format, or a dimensioned PDF, together with grade, quantity, critical tolerances and intended use. The MOQ is 1 piece, with samples usually in 3-7 days and batches usually in 10-15 days depending on complexity and quantity. Customer sample approval is required before batch production. An NDA can be signed for drawings involving unpublished designs.
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.
