Custom CNC Milling Services for Precision Metal and Plastic Parts
Get production-ready CNC milled parts with 3-, 4- and 5-axis machining, engineering DFM review, verified materials and documented inspection. Upload your CAD model and 2D drawing for a manufacturing review and detailed quotation.
- Metals & Engineering Plastics
- ISO 9001:2015 Quality System
- FAI, CMM Reports & Material Certificates Available
What Is CNC Milling?
CNC milling is a subtractive manufacturing process in which computer-controlled rotating cutting tools remove material from a solid workpiece. Depending on the geometry, the workpiece may be machined from several orientations using 3-axis, 4-axis or 5-axis equipment.
The process is suitable for prototypes, fixtures, housings, brackets, mold components and production parts made from metals or engineering plastics. Part geometry, material, tolerance, surface finish and production quantity are reviewed together before the machining method is selected.
CNC Milling Capabilities: 3-, 4- and 5-Axis Machining
Samshion selects the machining strategy according to part geometry, feature accessibility, tolerance requirements and production quantity. Using the appropriate axis configuration can reduce setups, control machining risk and improve dimensional consistency.
3-Axis CNC Milling
3-axis milling is suitable for parts with planar faces, pockets, holes, slots and profiles that can be reached from one primary orientation. It is generally the most economical option for straightforward prototypes, fixtures and production components.
4-Axis CNC Milling
4-axis milling adds controlled rotation of the workpiece. This improves access to side features and cylindrical surfaces while reducing manual repositioning between operations. It is useful for parts with features distributed around multiple sides.
5-Axis CNC Milling
5-axis milling allows the cutting tool to approach complex surfaces from multiple directions. It is suited to contoured components, impellers, precision housings, mold inserts and parts that would otherwise require several setups.
For projects that require simultaneous multi-axis movement or complex surface control, explore our dedicated 5-axis CNC machining service.
Why Choose Samshion for CNC Milling?
Samshion supports CNC milling projects from initial DFM review through machining, inspection and finishing. The manufacturing plan is developed around the drawing requirements instead of applying the same process to every part.
- ISO 9001 Certified: Quality-driven processes for aerospace, automotive, and medical industries.
- Free DFM Analysis: Optimize your design for manufacturability and cost efficiency.
- 24/7 Support: Expert engineers ready to resolve technical queries.
Engineering Review Before Machining
Our engineers review tool access, internal radii, deep pockets, thin walls, hole locations, datum requirements and other features that may affect cost or machining stability. Manufacturing concerns are communicated before production begins.
Process Selection Based on Part Geometry
Parts are assigned to suitable 3-axis, 4-axis or 5-axis equipment according to geometry and tolerance requirements. This helps reduce unnecessary setups while maintaining an efficient machining process.
Inspection Matched to Critical Features
Inspection planning is based on the dimensions, datums and tolerances identified on the 2D drawing. Calibrated measuring tools, optical inspection and CMM inspection can be used according to part requirements.
Machining and Finishing from One Supplier
CNC milling, deburring, surface preparation, finishing and inspection can be coordinated within one manufacturing workflow. This reduces communication gaps between machining and secondary operations.
CNC Milling from Prototype to Production
CNC milling can support development parts as well as repeat production. The machining plan, workholding and inspection approach are adjusted according to project maturity and expected quantity.
Prototype and Design Validation
Prototype milling produces parts in the intended engineering material so that fit, assembly and function can be evaluated before production. DFM feedback can identify features that may increase machining time or introduce unnecessary risk.
Bridge and Low-Volume Production
CNC milling is suitable for bridge production and low-volume orders where tooling investment may not be justified. Stable workholding and documented machining parameters help improve repeatability across the batch.
Repeat Production Batches
For recurring orders, machining programs, tooling information and inspection requirements can be retained for future batches. Production scheduling and batch quantities are reviewed according to demand, geometry and material availability.
CNC Milling Materials
Material selection affects machinability, dimensional stability, surface finish, tool wear and total part cost. We machine commonly specified metals and engineering plastics and review the exact grade, temper, stock form and certification requirements during quotation.
Material Verification and Traceability
When required by the project, incoming material can be checked against purchasing documents and material certificates. XRF verification may be used for applicable metallic alloys. Tell us during quotation if lot traceability, material certificates, RoHS or REACH documentation is required.
View our complete CNC machining materials guide for additional grades and material-selection information.
Description:
Aluminum alloys are engineered metallic materials composed primarily of aluminum combined with elements such as copper, magnesium, silicon, or zinc. Renowned for their exceptional strength-to-weight ratio, corrosion resistance, and versatility, aluminum alloys are widely used across industries ranging from aerospace to consumer electronics.
Alloys:
6061-T6, 7075-T6, 7050, 2024, 2A12,6082,5083,5052, 6063, MIC6.etc.
Finishing Options:
Alodine, Anodizing Types II, III, III + PTFE, ENP, Media Blasting, Nickel Plating, Powder Coating, Tumble Polishing.
Description:
Stainless steel is a corrosion-resistant iron-based alloy containing a minimum of 10.5% chromium, combined with elements like nickel, molybdenum, and carbon. Renowned for its durability, aesthetic versatility, and hygienic properties, stainless steel is a cornerstone material in industries ranging from medical devices to architectural design.
Alloys:
303, 304L, 316L, 410, 416, 440C, 17-4PH, Nitronic 60.etc.
Finishing Options:
Electropolishing, ENP, Media Blasting, Nickel Plating, Passivation, Powder Coating, Tumble Polishing, Black Oxide, Zinc Plating, Vibratory Tumbling.
Description:
Copper, a ductile and malleable metal with exceptional electrical and thermal conductivity, is a cornerstone of modern technology and industrial applications. Known for its natural reddish-brown hue, corrosion resistance, and recyclability, copper and its alloys are indispensable in sectors ranging from electronics to renewable energy.
Alloys:
C1100,C1011.etc.
Finishing Options:
Media Blasting, Nickel Plating, Passivation, Tumble Polishing, Vibratory Tumbling.etc.
Description:
Brass alloys are versatile metallic materials primarily composed of copper and zinc, often enhanced with elements like lead, tin, or aluminum. Known for their excellent machinability, corrosion resistance, and aesthetic appeal, brass alloys are widely utilized in industries such as plumbing, musical instruments, decorative hardware, and electrical components.
Alloys:
C260, C360, C464, C485, C280, C220, C230, C510, C544, C675.
Finishing Options:
Polishing, Electroplating (Nickel, Chrome), Clear Lacquering, Antiquing, Powder Coating, Passivation, Sandblasting, Brushed Finish, Hot-Dip Galvanizing, Laser Etching.
Description:
Steel alloys are engineered metallic materials primarily composed of iron and carbon, often enhanced with elements like chromium, nickel, or molybdenum. Renowned for their exceptional strength, durability, and resistance to wear and corrosion, steel alloys are extensively used in industries such as construction, automotive manufacturing, industrial machinery, and tooling.
Alloys:
1045 Carbon Steel, A36 Mild Steel, 4140 Chromoly Steel, 4340 High-Strength Steel, D2 Tool Steel, A2 Tool Steel, 52100 Bearing Steel, 8620 Case-Hardening Steel.
Finishing Options:
Heat Treatment (Quenching, Tempering), Galvanizing, Powder Coating, Electroplating (Nickel, Chrome), Media Blasting, Passivation, Polishing, Black Oxide Coating, Anodizing, Laser Engraving.
Description:
Titanium alloys are advanced metallic materials primarily composed of titanium blended with elements like aluminum, vanadium, or nickel. Renowned for their exceptional strength-to-weight ratio, corrosion resistance, and biocompatibility, titanium alloys are critical in high-performance industries such as aerospace, medical implants, marine engineering, and chemical processing.
Alloys:
Ti-6Al-4V (Grade 5), Ti-3Al-2.5V (Grade 9)
Finishing Options:
Anodizing (Type II, III), Media Blasting, Electropolishing, Passivation, Thermal Oxidation, PVD Coating, Laser Marking, Chemical Etching, Powder Coating, Grinding/Polishing.
Description:
Magnesium alloys are lightweight metallic materials primarily composed of magnesium combined with elements such as aluminum, zinc, or manganese. Renowned for their exceptional strength-to-weight ratio, vibration damping properties, and machinability, magnesium alloys are widely utilized in high-performance industries including aerospace, automotive lightweighting, consumer electronics, and biomedical devices.
Alloys:
AZ31B, AZ91D,
Finishing Options:
Anodizing (Type I, II), Chemical Conversion Coating (Chromate, Phosphate), Electroplating (Nickel, Copper), Powder Coating, Laser Etching, Passivation, Polishing, PVD Coating, Epoxy Sealing, Thermal Spraying.
Description:
ABS (Acrylonitrile Butadiene Styrene) is a versatile thermoplastic polymer celebrated for its excellent impact resistance, thermal stability, and ease of processing. Combining rigidity, surface gloss, and electrical insulation properties, ABS is extensively utilized in automotive parts, consumer electronics, household appliances, toys, and industrial piping systems.
Colors:
Opaque beige, Black.
Finishing Options:
As machined, Media blasting, Polishing, Painting, Texture coating, Clear lacquering, Electroplating
Description:
POM (Polyoxymethylene) is a high-performance engineering thermoplastic renowned for its exceptional mechanical strength, low friction coefficient, superior dimensional stability, and resistance to chemicals. With outstanding wear resistance and anti-creep properties, POM is widely used in precision mechanical components, gears, bearings, electronic connectors, medical devices, and automotive systems.
Colors:
White, Black.
Finishing Options:
As machined, Media blasting, Polishing,
Description:
Nylon is thermoplastic with high strength, wear resistance, excellent sound/vibration dampening, and low friction coefficient. It is commonly used in engineering and manufacturing processes. Common applications include gears, bearings, and bushings. Two of the most notable use cases for Nylon are in medical devices and electronics insulation, notably screws and spacers for panel mounted circuit boards.
Colors:
Opaque beige, Black.
Finishing Options:
As machined, Media blasting, Polishing,
Description:
PEEK, (polyether ether ketone) is a thermoplastic widely used in industries such as aerospace, automotive, and electronics. PEEK has high strength, stiffness, toughness, chemical, biocompatibility, and thermal resistance. Due to its , PEEK is also suitable for use in harsh environments where other materials may fail. Common applications include aircraft structures, electronic components that require high temperature resistance, and medical and dental components (including implantables).
Colors:
Opaque beige
Finishing Options:
As machined, Media blasting, Polishing,
Description:
PE is flexible, chemical-resistant, and impact-resistant.
Lightweight and cost-effective, this material is ideal for packaging, containers, and piping systems where durability and adaptability are essential.
Color:
Natural White,Black,
Finishing Options:
As machined, Sand blasting, Tumbling,
Description:
Polycarbonate (PC) is renowned for its exceptional clarity, high impact resistance, and thermal stability. Widely used in optical lenses, automotive components, and protective equipment, PC maintains structural integrity under stress while offering lightweight versatility.
Color:
Transparent,Black,
Finishing Options:
As machined, Media Blasting, Polishing, Anti-Scratch Coating, Painting, Textured Finish, Laser Etching
Description:
HIPS is lightweight, impact-resistant, and easy to machine.
Ideal for prototyping and consumer products, this material balances durability and cost-effectiveness while offering excellent surface finish for aesthetic applications.
Color:
Natural White,Black,
Finishing Options:
As machined, Media blasting, Polishing, Painting, Texture coating, Clear lacquering, Electroplating
Surface Finishes for CNC Milled Parts
Surface finishing can improve appearance, corrosion resistance, wear performance or electrical properties. The correct finish depends on material, dimensional requirements and the function of the finished part.
As Machined
Parts are supplied after machining and deburring, with normal tool marks remaining on machined surfaces. This is generally the most economical option for functional components.
Bead Blasting
Bead blasting produces a uniform matte appearance and can reduce the visibility of minor machining marks. Masking requirements and critical surfaces should be specified on the drawing.
Anodizing
Anodizing improves corrosion and wear resistance on aluminum parts and is available in different types and colors. Coating thickness should be considered on tight-tolerance features.
Chemical Conversion Coating
Chemical conversion coating provides corrosion protection for aluminum while maintaining electrical conductivity more effectively than anodizing. It is commonly used for electrical enclosures and functional components.
Passivation and Electropolishing
Passivation improves the corrosion resistance of stainless steel by removing surface contaminants. Electropolishing can further improve cleanliness, brightness and surface smoothness.
Powder Coating and Plating
Powder coating provides a durable colored coating, while nickel and other plating processes can improve corrosion resistance, conductivity or wear performance. Critical dimensions may require masking or post-finish inspection.
See our complete surface finishing options for available processes, colors and material compatibility.
CNC Milling Tolerances and Drawing Requirements
CNC milling tolerance depends on part size, material, feature geometry, tool access, wall thickness, surface finish and inspection method. Critical requirements should be identified clearly before quotation.
For critical dimensions, provide a 2D drawing that identifies:
- Dimensional tolerances
- Datum references
- Geometric tolerances
- Surface-roughness requirements
- Thread specifications
- Coating or finishing requirements
- Inspection-report requirements
General dimensions can be produced according to an agreed drawing standard. Tighter dimensions are reviewed feature by feature during DFM analysis. Avoid presenting one tolerance value as achievable on every dimension of every part.
Standard Tolerances for Linear Dimensions (ISO 2768)
At Samshion, we adhere to ISO 2768 standards for precision:
Values in millimeters
| Basic Size Range | Fine (±) | Medium (±) | Coarse (±) | Very Coarse (±) |
|---|---|---|---|---|
| 0.5 ≤ 3 | 0.05 | 0.1 | 0.2 | – |
| >3 ≤ 6 | 0.05 | 0.1 | 0.3 | 0.5 |
| >6 ≤ 30 | 0.1 | 0.2 | 0.5 | 1 |
| >30 ≤ 120 | 0.15 | 0.3 | 0.8 | 1.5 |
| >120 ≤ 400 | 0.2 | 0.5 | 1.2 | 2.5 |
| >400 ≤ 1000 | 0.3 | 0.8 | 2 | 4 |
| >1000 ≤ 2000 | 0.5 | 1.2 | 3 | 6 |
| >2000 ≤ 4000 | – | 2 | 4 | 8 |
Quality Control for CNC Milled Parts
Quality planning begins with the drawing and continues through material verification, machining and final inspection. Inspection scope is matched to the functional requirements of the part.
Learn more about our quality assurance and inspection process.
Material and Document Review
Material grade, certification requirements, revision level and critical drawing notes are confirmed before machining begins. Material certificates and traceability documents can be supplied when requested during quotation.
In-Process and Final Inspection
Machinists and inspectors check critical features during production and after machining. Depending on the geometry and tolerance, inspection may use calipers, micrometers, height gauges, optical systems or coordinate measuring machines.
Quality Documentation
Available documentation may include first article inspection reports, dimensional inspection reports, CMM reports, material certificates and Certificates of Conformance. Required reports should be specified before the order is placed.
CNC Milling Design Guidelines
Good milling design improves tool access, machining stability and inspection reliability while helping control production cost.
Internal Corners and Tool Radius
Rotating end mills cannot produce perfectly sharp internal corners. Use the largest practical internal radius and avoid specifying a radius equal to the cutting-tool radius. Features that require very small radii should be identified for engineering review.
Pocket Depth and Tool Access
Deep, narrow pockets require long cutting tools, which can increase vibration and tool deflection. Whenever possible, use wider pockets, larger corner radii and open access for the cutting tool.
Wall Thickness
Very thin or uneven walls can move during machining and may distort after material is removed. Maintain consistent wall thickness where possible and allow additional support for tall or flexible features.
Holes and Threads
Use standard drill and thread sizes when possible. Specify thread standard, size, class, depth and whether a hole is through or blind. Allow clearance for drilling and tapping tools at the bottom of blind holes.
Undercuts
Undercuts require specialized tools and may increase setup time. Use standard undercut profiles where possible and specify the width, depth, radius and access direction on the drawing.
Engraving and Marking
Use clear fonts and adequate line width for machined text. Engraving depth, character height and final surface treatment should be reviewed together to maintain legibility.
Read our detailed guide to internal corner radius in CNC milling for additional DFM recommendations.
Frequently Asked Questions (FAQ)
What materials can be used for CNC milling?
We machine aluminum, stainless steel, steel, brass, copper, titanium and a range of engineering plastics including POM, nylon, ABS, polycarbonate and PEEK. Exact availability depends on grade, temper, stock size and certification requirements.
What is a typical CNC milling tolerance?
A typical starting tolerance for many CNC-milled features is ±0.05 mm. Tighter tolerances may be possible on selected dimensions depending on part size, material, geometry and inspection method. Identify all critical dimensions on a 2D drawing so they can be confirmed before quotation.
How long does CNC milling production take?
Lead time depends on geometry, material availability, quantity, tolerance, inspection scope and surface finishing. The expected production schedule is confirmed after engineering review. Expedited scheduling may be available for suitable projects.
Can Samshion handle prototypes and low-volume orders?
Yes. CNC milling is suitable for single prototypes, design-validation parts, bridge production and repeat low-volume batches. The manufacturing approach is adjusted according to quantity and expected future demand.
What surface finishes are available?
Available options include as-machined, bead blasting, anodizing, chemical conversion coating, passivation, electropolishing, powder coating, black oxide and plating. Finish compatibility depends on the base material and dimensional requirements.
How do you inspect CNC milled parts?
We use incoming material checks, in-process inspection and final dimensional inspection. Depending on project requirements, we can provide CMM reports, first article inspection reports, material certificates and Certificates of Conformance.
How can I request a CNC milling quote?
Upload your 3D CAD model and, when available, a 2D engineering drawing. Include the material, quantity, surface finish, critical tolerances and inspection-document requirements so our engineers can prepare an accurate quotation.
