Custom Precision Carbon Steel CNC Milled Parts
Overview
We provide CNC milling for carbon steel mounting plates, bearing housings, valve blocks and guide seats, including mounting faces, steps, pockets and hole patterns for structural parts in heavy-duty equipment, hydraulic systems and test rigs. 45#, Q235 and 20# have different properties and are not interchangeable. Machining is planned according to the grade and heat treatment condition specified on the drawing. The MOQ is 1 piece. Samples usually take 3-7 days and general orders usually take 10-15 days, depending on complexity and quantity.
Key Capabilities
- Materials: 45#, Q235, 20# carbon steel; grade and material standard per drawing
- Tolerance: +/-0.003 mm (+/-0.00012 inch), IT5 or IT6 accuracy, +/-0.01 mm shaft/bore fits; h6/H7 available
- Surface Finish: Milled surfaces Ra 3.2 um; finish-milled functional faces Ra 1.6 um
- GD&T: Flatness 0.02 mm on areas up to 1030 x 1030 mm; hole-pattern position 0.015 mm, subject to datum and inspection requirements
- Max Size: 3-axis machine travel 3000 x 1600 x 1400 mm; workpiece size depends on fixturing and setup
- Surface Treatment: Zinc, nickel, or chrome plating 3-20 um; masking and fit allowance per drawing
- Thread: Internal threads from M1.4, thread depth up to 4 x D, blind-hole effective depth up to 50 mm; go/no-go gauge inspection, standard per drawing
- Precision Limit: +/-0.003 mm on precision features and small critical dimensions (parts under 100 mm); +/-0.05 mm on parts over 500 mm; pocket depth-to-width up to 4:1, or 5:1 with extended tools
Carbon Steel Milling for Load-Bearing Faces and Hole Patterns
Mounting faces and hole patterns determine whether a part aligns correctly on the equipment. Flatness can reach 0.02 mm over machining areas up to 1030 x 1030 mm, and hole-pattern position can reach 0.015 mm. Multi-face mounting parts may also require perpendicularity, such as 0.02 mm / 1000 mm. Such requirements need defined datum faces, machining heights and inspection methods.
Carbon Steel Milled Pockets and Internal Corner Access
Pockets can support a depth-to-width ratio of 4:1, or 5:1 with extended tools. Longer tool extension has a greater effect on surface quality. The minimum internal corner radius achievable with an end mill is R0.5 mm; for cavities 40 mm deep, R1.0 mm is recommended. Perfectly sharp internal corners require EDM or a design adjustment.
Stress Control for Large Carbon Steel Milling
Removing large amounts of material releases residual stress in the blank. Mounting faces may warp, and the relative positions of hole patterns and datums may change. The minimum wall thickness capability of 0.5 mm requires blank pretreatment, stress-relief aging and optimized machining parameters. For large plates, clamping methods and datum selection also affect final flatness.
Heat-Treated Carbon Steel Milling and Final Fits
Heat treatment increases hardness and wear resistance in grades such as 45#, but can also change dimensions. Drawings must specify the heat treatment condition and whether mating surfaces are accepted to pre-treatment or post-treatment dimensions. Where mating surfaces require IT5 or IT6 accuracy, necessary secondary operations such as grinding can be added according to the drawing. The route is evaluated against dimensions, material and geometry.
Specifications
| Product Name | Custom Precision Carbon Steel CNC Milled Parts |
|---|---|
| Manufacturer | XCM CNC |
| Factory Location | Shenzhen, Guangdong, China |
| Quality System | ISO 9001, ISO 13485, IATF 16949, GJB9001C |
| Machining Process | CNC milling, drilling, boring, and secondary grinding as required |
| Material | Carbon steel |
| Material Grade | 45#, Q235, 20#; verify grade and material standard against drawing |
| Tolerance | +/-0.003 mm on precision features and small critical dimensions (parts under 100 mm); +/-0.05 mm on parts over 500 mm |
| Surface Treatment | Zinc, nickel, or chrome plating, 3-20 um; masking and fit allowance per drawing |
| Max Part Size | Milling workpiece length up to approximately 2600 mm, depending on geometry, fixturing, and setup |
| Inspection | CMM and FAI reports available; report scope per order |
| Application | Mounting plates, bearing-seat blocks, valve blocks, and heavy-duty equipment interfaces |
| Key Features | Milled mounting faces, steps, hole patterns, and pockets; pocket depth-to-width ratio 4:1, up to 5:1 with extended tools |
| Critical QC Requirements | Flatness 0.02 mm on areas up to 1030 x 1030 mm; hole-pattern position 0.015 mm with defined datum and inspection method |
| MOQ | 1 Piece |
| Typical Lead Time | 10-15 business days after drawing review |
| Drawing Formats | STEP, IGS, DWG, PDF, X_T |
Applications
Guide Rail Mounting Plates for Industrial Automation
Guide rail mounting plates and machine connection plates join rails, frames and drive units. Mounting-face flatness and the relative positions of multiple fastening holes directly affect rail alignment after assembly, so mounting faces, steps and hole patterns need to be milled from a common datum. Carbon steel suits mounting locations that carry structural loads and are not weight-sensitive.
Bearing Housings and Mounting Brackets for Construction Machinery
Bearing housings and equipment mounting brackets secure rotating or drive components. Load-bearing faces, areas around bearing bores and bolt holes must relate to one another. Where bores require H7 or H8 fits, milling can be combined with boring, with bored surface roughness of Ra 1.6 um. The specified grade and heat treatment condition are defined by the drawing.
Valve Blocks and Pump Mounting Blocks for Hydraulic Equipment
Hydraulic valve blocks and pump mounting blocks feature external mounting faces, counterbores, locating holes and seal grooves. O-ring grooves have a minimum width of 1.0 mm and a depth tolerance of 0.01 mm. Cross-hole deburring and internal passages are also within the machining scope. Specify sealing-face roughness and flatness, cleanliness, leak testing and plug arrangements together in the order.
Guide Seats and Wear Locating Blocks for Heavy Equipment
Guide mounting seats and wear locating blocks limit component movement and provide contact locating surfaces. Symmetry between guide slots and the central structure can be evaluated at 0.02 mm, with a defined design datum. Where heat treatment or specified hardness is required, the machining sequence follows the drawing grade and order conditions.
Test Stand and Large Equipment Bases
A test stand mounting base supports actuators, fixtures or measuring components and typically has large datum faces and distributed hole patterns. Three-axis travel is 3000 x 1600 x 1400 mm, with workpiece lengths up to approximately 2600 mm depending on part shape and setup. Datums for base-face flatness and the relative positions of hole patterns must be established during quotation.
Why Choose Us
ISO Quality Systems and Multi-Brand Equipment for Carbon Steel Milling
Factory quality systems include ISO 9001, ISO 13485, IATF 16949 and GJB9001C. Machining equipment from DMG, Mazak, Matsuura and Brother supports carbon steel milling orders from prototypes through batch production.
Milling Support from Small Connectors to Large Plates
We machine parts ranging from small connectors to large structural parts. Carbon steel plates can use milling machines with 3-axis travel of 3000 x 1600 x 1400 mm, with drawing-based drilling, boring or grinding to complete mounting faces, hole patterns and mating surfaces.
Equipment Matched to Accuracy, Quality and Cost
Machines are selected from four equipment tiers from mainland China, Taiwan, Japan, and Europe and the United States according to part and operation accuracy requirements. High-precision mating surfaces and less demanding external surfaces are assigned separately, without fixed process roles predetermined by equipment brand.
Coordinating Dimensions before and after Plating
Zinc, nickel or chrome coatings of 3-20 um affect holes, threads and mating dimensions. During quotation, we establish with you which features require post-plating dimensional acceptance and which areas require masking.
Sample Approval before Production, with Order-Based Inspection Documents
Production begins after sample approval so you can verify assembly interfaces first. CMM reports, FAI reports and material certificates can be supplied according to the order, with the inspection scope agreed between you and us. An NDA can be signed when confidentiality is required.
FAQ
How should I choose between Q235, 45# and 20# steel for a milled part?
45# is a medium-carbon steel that can gain strength and wear resistance through heat treatment, making it suitable for load-bearing parts or parts subject to contact wear. Q235 is a lower-strength, low-carbon structural steel commonly used for general structures. 20# is a low-carbon steel often used for parts requiring surface carburizing. Determine the grade from drawings, material standards and material certificates. Do not infer hardness or use from the name “carbon steel” alone.
Can you machine deep pockets with sharp internal corners?
An end mill cannot produce perfectly sharp internal corners. The minimum internal corner radius is R0.5 mm, with R1.0 mm recommended for cavities 40 mm deep. Pocket depth-to-width ratios can reach 4:1, or 5:1 with extended tools. Where sharp corners must be retained, EDM or a design adjustment is required.
What tolerance and size can I expect on a large milled steel plate?
Three-axis travel is 3000 x 1600 x 1400 mm, with workpiece lengths up to approximately 2600 mm depending on part shape and setup. Parts over 500 mm use a dimensional tolerance of +/-0.05 mm. Flatness of 0.02 mm applies to machining areas up to 1030 x 1030 mm. Identify the datum faces and hole patterns that actually affect assembly on the drawing.
Should a carbon steel part be heat treated before or after milling?
This depends on which dimensions require acceptance after heat treatment. Heat treatment can change dimensions, so high-precision mating surfaces are generally finished afterward, with grinding where necessary. Specify the heat treatment condition and hardness on the drawing, and state whether mating-surface acceptance applies to pre-treatment or post-treatment dimensions.
How does zinc plating affect locating holes?
Coatings reduce bore diameters and increase shaft diameters, affecting the final dimensions of locating holes and mating surfaces. Zinc, nickel and chrome coating thicknesses range from 3-20 um. Specify thickness, surfaces requiring masking and whether hole and thread dimensions are accepted before or after plating.
Can you report flatness and hole-pattern position?
Yes. Flatness and hole-pattern position can be measured by CMM and reported, with report format and inspection scope determined by order requirements. Before quotation, identify datum faces and the hole patterns requiring inspection so the measurement method matches drawing position requirements.
How are milled carbon steel parts packed and shipped?
Packaging uses foam plus cartons or wooden cases according to part size and weight. Shipping options include DHL, FedEx, UPS and sea freight. State any rust-protection requirements in the order so they can be agreed with you before shipment.
What information do you need to quote a milled carbon steel part?
Provide 2D/3D drawings, the material grade and standard, quantity, tolerances and intended use. Identify critical datums, heat treatment and surface-treatment requirements. Accepted formats include STEP, IGES, STP, DWG and dimensioned PDF. The MOQ is 1 piece, and samples usually take 3-7 days.
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.
