CNC Machining Materials Guide
Compare 20+ metals and plastics — aluminium alloys, stainless steel grades, titanium, brass and engineering plastics. Machinability ratings, tensile strength, cost and applications explained.
Quick Comparison Table
Use this table to shortlist materials before diving into the detailed sections below. Machinability is rated 1–10 (10 = easiest to machine).
| Material | Family | Tensile Strength | Machinability | Corrosion Resistance | Relative Cost | Best For |
|---|---|---|---|---|---|---|
| Aluminium 6061-T6 | Aluminium | 310 MPa | 9/10 | Good | $ | General purpose, enclosures, frames |
| Aluminium 7075-T6 | Aluminium | 572 MPa | 8/10 | Moderate | $$ | Aerospace, high-stress brackets |
| Aluminium 2024-T4 | Aluminium | 470 MPa | 8/10 | Low | $$ | Aircraft skins, structural panels |
| Stainless 303 | Stainless Steel | 620 MPa | 8/10 | Excellent | $$ | Shafts, fasteners, fittings |
| Stainless 304 | Stainless Steel | 515 MPa | 6/10 | Excellent | $$ | Food, medical, welded assemblies |
| Stainless 316 | Stainless Steel | 579 MPa | 5/10 | Superior | $$$ | Marine, chemical, pharmaceutical |
| Stainless 17-4 PH | Stainless Steel | 1170 MPa | 5/10 | Good | $$$ | Aerospace, oil & gas, high-load |
| Carbon Steel 1018 | Steel | 440 MPa | 8/10 | Poor | $ | Shafts, gears, case-hardened parts |
| Alloy Steel 4140 | Steel | 1020 MPa | 6/10 | Poor | $$ | Dies, heavy machinery, drivetrain |
| Titanium Grade 2 | Titanium | 344 MPa | 3/10 | Excellent | $$$$ | Medical implants, chemical equipment |
| Titanium Ti-6Al-4V | Titanium | 950 MPa | 2/10 | Excellent | $$$$ | Aerospace, surgical instruments |
| Brass C360 | Brass/Copper | 385 MPa | 10/10 | Good | $$ | Fittings, valves, electrical connectors |
| Copper C110 | Brass/Copper | 220 MPa | 9/10 | Good | $$$ | Electrical bus bars, heat sinks |
| PEEK | Plastic | 100 MPa | 6/10 | Excellent | $$$$$ | Medical, chemical, extreme temp |
| Delrin (POM) | Plastic | 70 MPa | 9/10 | Good | $$ | Gears, bearings, bushings |
| Nylon (PA6/66) | Plastic | 80 MPa | 8/10 | Good | $ | Wear parts, brackets, housings |
Machined in Pune — Delivered Worldwide
Every material in this guide is stocked and processed at our facility in Pune, India. Our 4-axis and 5-axis CNC machining centres hold tolerances to ±0.01 mm, and our in-house metrology lab verifies every critical dimension before dispatch. Whether you need a single prototype in Ti-6Al-4V or a production run of 10,000 aluminium brackets, our team reviews your drawings, optimises tool-paths for the chosen material, and quotes within 24 hours.
Sourcing from Survi versus a Western supplier typically saves 40–70% on unit cost — without sacrificing lead time, quality documentation, or engineering support.
Get a QuoteAluminium Alloys
Aluminium is the most widely used CNC machining material — light, strong, corrosion-resistant and fast to machine. The four most common alloys for precision parts are:
6061-T6 Most Popular
The go-to general-purpose alloy. Excellent weldability, good anodizing response and the best balance of strength, cost and machinability. Used in everything from enclosures and brackets to bicycle frames and drone bodies.
7075-T6 Aerospace Grade
Nearly twice the tensile strength of 6061. The standard choice when strength-to-weight ratio is critical — aircraft frames, UAV components, high-load brackets. Not weldable (without special techniques) and costs 30–50% more than 6061.
2024-T4 Aircraft Structural
High fatigue resistance, used in aircraft fuselage skins and structural panels. Poor corrosion resistance (usually clad or anodized). Not commonly used outside aerospace due to welding limitations.
5052-H32 Sheet Metal
The most common alloy for sheet metal fabrication — excellent formability and the best corrosion resistance of all aluminium alloys. Lower strength than 6061 but superior for marine environments and bending applications.
Why Aluminium Dominates CNC Machining
Aluminium alloys account for over 60% of all CNC machining orders globally — and for good reason. They machine 3–5× faster than steel, require no pre-heat or post-weld stress relief, and accept a wide variety of finishing options from anodizing to powder coating. The result: lower cycle times, longer tool life, and finished parts that look and feel premium.
At Survi, aluminium is our most common material. We carry 6061, 7075, 2024 and 5052 in bar, plate and tube stock, enabling same-week starts on most orders without waiting for material procurement.
Stainless Steel
Stainless steel combines corrosion resistance with high strength. The key trade-off is machinability — austenitic grades (303/304/316) work-harden rapidly and require sharp tooling and lower cutting speeds.
303 Stainless Best Machinability
The most machinable stainless steel — sulphur addition breaks chips and reduces cutting forces. Industry standard for turned parts: shafts, standoffs, fittings. Not weldable (sulphur causes weld porosity).
304 Stainless Food & Medical
The most widely used stainless steel grade globally. Food-safe, weldable, and suitable for many medical applications. Harder to machine than 303 due to work-hardening — use sharp HSS or carbide tooling and high coolant flow.
316 Stainless Marine/Chemical
Molybdenum addition gives superior resistance to chlorides and pitting — the choice for marine hardware, chemical processing and pharmaceutical equipment. More expensive and slower to machine than 304.
17-4 PH Stainless High Performance
Precipitation-hardened grade with tensile strength exceeding 1,170 MPa — among the highest of any stainless steel. Used in aerospace fasteners, surgical tools and oil & gas components where both strength and corrosion resistance are mandatory.
Machining Stainless Steel — What to Expect
Stainless steel presents unique machining challenges compared to aluminium. Austenitic grades (303, 304, 316) work-harden rapidly — if your cutting tool dwells or rubs rather than cutting, the surface hardens and tool wear accelerates dramatically. The solution: maintain constant feed, use sharp carbide tooling, and flood with coolant.
Our stainless machining capabilities at Survi include turning up to ø300 mm diameter, 5-axis milling, and CMM inspection on every tight-tolerance feature. We supply material test certificates (EN 10204 3.1) for all stainless steel orders.
Carbon & Alloy Steel
1018 Mild Steel Best Value
The most economical steel for CNC machining. Excellent machinability and weldability. Frequently case-hardened or carburized for wear surfaces. No inherent corrosion resistance — paint or plate after machining.
4140 Alloy Steel High Strength
Chromium-molybdenum alloy steel with outstanding fatigue and torsional strength. Through-hardenable to ~54 HRC. Ideal for dies, gears, shafts and heavy-duty machinery components that require both strength and toughness.
Steel: Strength Where It Matters
Carbon and alloy steels remain the backbone of industrial manufacturing — gears, shafts, dies, structural brackets, and drivetrain components. Their combination of tensile strength, weldability, and low base cost makes them indispensable for heavy-duty applications where aluminium's lower strength ceiling is a limiting factor.
When heat treatment is specified (through-hardening 4140 to ~54 HRC, for example), we coordinate with our partner heat-treatment facility and re-inspect critical dimensions after treatment to account for any distortion during quench.
Titanium
Titanium combines aerospace-grade strength with biocompatibility and excellent corrosion resistance. It machines slowly and wears tooling quickly — expect 4–6× higher machining costs versus aluminium, mitigated significantly by sourcing from Survi Engineering in India.
Titanium Grade 2 Commercially Pure
Commercially pure titanium — outstanding corrosion resistance (including HF acid) and biocompatibility. Used for medical implants, chemical processing equipment and offshore hardware. Lower strength than Ti-6Al-4V.
Ti-6Al-4V (Grade 5) Aerospace Standard
The workhorse of aerospace and medical manufacturing — 950 MPa tensile strength at just 4.43 g/cm³. Strongest titanium alloy in common use. Used for turbine blades, orthopedic implants, UAV structures and high-performance automotive parts.
Brass & Copper
Brass C360 Most Machinable Metal
Free-machining brass — rated 10/10 for machinability, the highest of any metal. Excellent for high-volume turned parts: valves, fittings, electrical connectors. Good corrosion resistance and natural antimicrobial properties.
Copper C110 High Conductivity
99.9% pure copper — electrical conductivity of 101% IACS, the highest of any common machining metal. Used for bus bars, heat sinks, induction coils and electrodes. Soft and gummy — requires sharp tooling and slow feeds.
Engineering Plastics
Engineering plastics are increasingly specified for CNC parts where weight reduction, chemical resistance or electrical isolation is needed. They machine quickly but require careful fixturing to prevent deformation.
PEEK Premium Plastic
Highest performance engineering plastic — continuous service to 260°C, exceptional chemical resistance and inherent flame retardancy. Used in semiconductor, medical and aerospace applications.
Delrin (POM) Best Dimensional Stability
Outstanding dimensional stability, low friction and excellent fatigue resistance. The first choice for precision gears, bushings, rollers and bearing surfaces where moisture or lubricants are present.
Nylon (PA6/66) Cost-Effective
Good mechanical properties, excellent abrasion resistance and low cost. Absorbs moisture which can affect dimensions in precision applications — use Delrin when tight tolerances are required.
How to Choose the Right Material
Ready to Order Your Parts?
Upload your CAD file and get an instant quote. We machine all materials listed on this page — aluminium, steel, titanium, brass and plastics — from our facility in Pune, India, at 40–70% less than US or European suppliers.
Frequently Asked Questions
Common questions about materials for CNC machining — which alloy to choose, what the difference between similar grades is, what certifications you receive, and how to order a material not listed.
What is the best material for CNC machining?
Aluminium 6061-T6 is the best default choice — it machines 3× faster than steel, offers an excellent strength-to-weight ratio, takes anodizing well, and is the most cost-effective option for most applications. Upgrade to 7075-T6 when you need significantly higher strength (aerospace, UAV, high-load brackets). Use stainless 303 when corrosion resistance is required without sacrificing machinability. Reserve titanium for applications that genuinely need its strength-to-weight advantage — it is 4–6× more expensive to machine than aluminium.
What is the difference between 6061 and 7075 aluminium for CNC machining?
6061-T6: tensile strength ~310 MPa, general-purpose, weldable, widely available, cheapest to machine. 7075-T6: tensile strength ~570 MPa (nearly double), used for aerospace and high-load applications, cannot be welded easily, costs 30–50% more. For most parts — housings, brackets, panels, fixtures — 6061 is the right choice. Choose 7075 only when structural analysis shows 6061 is insufficient. Our engineers are happy to advise if you share your application loading requirements.
Is stainless 303 or 304 better for CNC machining?
303 is much better for machining — sulphur additions give it roughly 3× the machinability of 304, meaning faster cutting speeds, less tool wear, and better surface finish. Use 303 for machined parts that don't need welding. Use 304 only when welding is required or when food-grade certification (FDA-compliant) is needed. 316 adds molybdenum for stronger corrosion resistance in chloride environments (marine, medical implants). We stock all three — price difference is modest.
How much does titanium CNC machining cost compared to aluminium?
Titanium (Ti-6Al-4V) is typically 4–6× more expensive to machine than aluminium 6061 due to slow cutting speeds, high tool wear, and the need for flood coolant. However, at Survi Engineering our titanium machining is still 50–65% cheaper than equivalent US or European suppliers. A titanium aerospace bracket that costs $800 domestically in the US typically costs $280–350 from Survi, including international shipping and duty.
Do you supply material certifications with every order?
Yes — every order includes a Mill Test Certificate (MTC) verifying chemical composition and mechanical properties, and a Certificate of Conformance (CoC) confirming parts were manufactured to the specified drawing. For aerospace and defence parts, we maintain lot traceability per AS9100 Rev D and can provide First Article Inspection Reports (FAIR). Medical device components are manufactured under ISO 13485-aligned practices. Certifications are included — not an add-on.
What engineering plastics can you machine?
We machine PEEK (highest performance, chemically resistant, medical-grade available), Delrin/POM (excellent dimensional stability, self-lubricating), Nylon 6/66 (cost-effective, good impact resistance), PTFE (non-stick, chemically inert, low friction), and UHMW-PE (outstanding impact resistance). Plastics machine quickly but require sharp tooling and careful fixturing to prevent thermal distortion — we've optimised our toolpaths for each material.
Can I order a material not listed on this page?
Yes. This guide covers the most common materials but is not exhaustive. We also machine Inconel, Hastelloy, duplex stainless steels, copper alloys (C101, C260 brass), tool steels (D2, H13) and carbon fibre composites. Email [email protected] with your material specification and application — our engineering team will advise on machinability, lead time and pricing.