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CNC Machining Materials We Stock and Support

A Guide to Metals in CNC Machining


At Rapid CNC Parts.com, we stock a curated range of USA-sourced metals selected for their compatibility with high-speed, precision CNC machining. Our flagship material, 6061 aluminum, is ideal for prototypes and production parts alike—offering excellent machinability, strength, and durability. This guide outlines all materials supported by our Instant Quote system so you can design with confidence and get your parts delivered fast.

Aluminum Bar Stock

Comparison of Material Types and Properties

Material

MachinabilityCostStrength & DurabilityHardness (Rockwell)DuctilityDensity (g/cm³)
Aluminum (6061)★★★★★★★★★★★★★B60High2.70
Aluminum* (7075)★★★★★★★★★★★★B87Medium2.81
Stainless Steel* (304)★★★★★★★★★★B80High8.00
Stainless Steel* (316)★★★★★★★★★B79High8.00
Stainless Steel* (17-4)★★★★★★★★★★C35Medium7.75
Steel* (1018)★★★★★★★★★★★★★B71High7.87
Steel* (4140)★★★★★★★★★★★★C32Medium7.85
Tool Steel* (D2)★★★★★★★★★★C62Low7.70
Tool Steel* (O2)★★★★★★★★★★★C57Medium7.85
Brass*★★★★★★★★★★★★B55High8.50
Copper*★★★★★★★★★B40High8.96
Titanium* (Grade 5)★★★★★★★C36Medium4.43
Inconel* (718)★★★★★C40Low8.19

Bronze*

★★★★

★★★★

★★★★

B65-B75

Medium

8.80

 * - AVAILABLE IN THE FUTURE - PLEASE SUBSCRIBE TO OUR NEWSLETTER FOR UPDATES!

*Material CURRENTLY Available for Instant Quote*
*Material COMING SOON to Instant Quote*

★★★★★ (5 stars)

​Most affordable, readily available, and widely used metals.

★★★★ (4 stars)

Moderately priced, balancing performance and cost.

★★★ (3 stars)

Moderately priced, balancing performance and cost.

★★ (2 stars)

Higher priced due to specialized applications, material properties, or processing difficulties.

★ (1 star)

Highest priced, rare, specialized alloys with challenging sourcing, machining complexity, and exceptional performance properties.

NOTE and DISCLAIMER: This table does not represent actual inventory available and is a general representation of the materials commonly used in machining and general availability. Materials available in the instant quote are stocked and generally available with the lead time quoted. Please contact us if you'd like us to quote a project in a material that is not currently offered through our instant quote process.



Steel Bar Stock

CNC Machining Materials: Properties, Performance, and Use Cases

Aluminum 6061


6061 Aluminum is highly versatile and popular for CNC machining due to its excellent machinability, weldability, and good corrosion resistance. Its moderate strength makes it suitable for a wide range of applications, including automotive components, aerospace parts, bicycle frames, and electronic enclosures. It is the most common choice for prototypes and production parts requiring a balance of performance, cost-efficiency, and availability.

Aluminum 7075


7075 Aluminum offers exceptional strength-to-weight ratio and superior hardness compared to other aluminum alloys. It is less corrosion resistant than 6061 but offers much higher mechanical performance. Commonly used for aerospace structures, military equipment, sports gear, and high-performance automotive parts due to its strength and durability. It’s ideal for lightweight, high-stress applications where performance is critical.

Stainless Steel 304


304 Stainless Steel provides excellent corrosion resistance, weldability, and good machinability. Widely employed in the food processing, kitchen appliances, medical instruments, and general industrial applications for its durability and aesthetic appeal. It performs well in moderately corrosive environments but may not be ideal for saltwater or chemical exposure.

Stainless Steel 316


316 Stainless Steel exhibits outstanding corrosion resistance, particularly in harsh chemical and marine environments. It retains high ductility and is commonly employed in marine fittings, medical implants, chemical containers, and pharmaceutical equipment. It offers better performance than 304 in chloride environments and is considered a premium stainless option.

Stainless Steel 17-4


17-4 Stainless Steel, a precipitation-hardened alloy, offers excellent strength, hardness, and moderate ductility. It can be heat treated to enhance mechanical properties and provides excellent corrosion resistance. It is highly valued for aerospace, petrochemical hardware, pump shafts, and demanding structural parts requiring both strength and corrosion resistance.

Steel 1018


1018 Carbon Steel is known for excellent machinability, weldability, formability, and high ductility, making it suitable for fixtures, shafts, pins, and various mechanical components. It is commonly used in general-purpose engineering and offers a cost-effective choice for low-stress applications.

Steel 4140


4140 Alloy Steel combines superior toughness, high strength, moderate ductility, and fatigue resistance, ideal for gears, shafts, bolts, axles, and high-stress structural applications. It can be heat treated for increased hardness and is widely used in tooling, agricultural, and automotive industries.

Tool Steel D2


D2 Tool Steel is an air-hardening, high-carbon, high-chromium tool steel known for excellent wear and abrasion resistance. It is widely used for manufacturing cutting tools, dies, punches, and blades requiring extended durability. It holds a sharp edge well and is favored in high-volume, high-wear production tooling.

Tool Steel O2


O2 Tool Steel is an oil-hardening steel recognized for its good machinability, stability during heat treatment, and reasonable toughness. Typically utilized for making gauges, punches, dies, and small tool components. It offers a good balance of hardness and machinability for non-complex tooling applications.

Brass


Brass is valued for excellent machinability, corrosion resistance, electrical conductivity, and high ductility, making it suitable for plumbing fittings, electrical connectors, valves, gears, and decorative items. Its low friction and anti-sparking properties also make it ideal for use in hazardous environments and fine mechanical assemblies.

Bronze

 Bronze is a durable, corrosion-resistant alloy commonly used in machined parts requiring excellent wear properties and low friction. It's ideal for bushings, bearings, thrust washers, gears, and components in marine or heavy-duty mechanical environments. With good machinability and strength, bronze offers a reliable solution where long service life and reduced metal-on-metal contact are critical. Certain bronze grades also resist galling and perform well under continuous motion.

Copper


Copper is known for exceptional electrical and thermal conductivity, excellent ductility, and machinability. Frequently machined for electrical wiring, heat exchangers, and cooling systems. Its softness and cost make it less ideal for structural applications but invaluable for electrical and thermal transfer requirements.

Titanium Grade 5


Grade 5 Titanium provides an outstanding strength-to-weight ratio, high corrosion resistance, and medium ductility, widely used in aerospace, automotive performance parts, marine hardware, and medical implants. It is biocompatible, weldable, and can withstand extreme environments. Titanium is challenging to machine but delivers unmatched performance where weight savings are critical.

Inconel 718


Inconel 718, a nickel-based superalloy, is recognized for exceptional strength, corrosion resistance, and hardness at extreme temperatures. It has lower ductility but excels in aerospace applications, turbine blades, and nuclear reactors. Inconel is difficult to machine but is chosen for applications where performance must be maintained under the harshest thermal and mechanical stress.

Material Test Reports (MTRs)


We offer Material Test Reports (MTRs) for all metals upon request. These reports provide certified verification of material properties, ensuring compliance with industry standards and project​ specifications. 


Request your MTR when placing an order to guarantee material traceability and quality assurance.

Material Test Report Icon 

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