Skip to Content

Our Materials

A Guide to Metals in CNC Machining


At Rapid CNC Parts, we stock a selection of USA-sourced materials engineered for high-speed, precision CNC machining. Our primary material, Aluminum 6061, is known for its excellent machinability, high strength, and long-term durability—making it the ideal choice for both prototypes and production parts. This guide highlights the materials supported by our Instant Quote system so you can design with confidence and get parts delivered fast.

Aluminum Bar Stock

Comparison of Material Types and Properties

MaterialMachinabilityCostStrength & 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

 * - 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

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.

Aluminum 7075


7075 Aluminum offers exceptional strength-to-weight ratio and superior hardness compared to other aluminum alloys. Commonly used for aerospace structures, military equipment, sports gear, and high-performance automotive parts due to its strength and durability.

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.

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.

Stainless Steel 17-4


17-4 Stainless Steel, a precipitation-hardened alloy, offers excellent strength, hardness, and moderate ductility. It is highly valued for aerospace, petrochemical hardware, pump shafts, and demanding structural parts.

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.

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.

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.

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.

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.

Copper


Copper is known for exceptional electrical and thermal conductivity, excellent ductility, and machinability. Frequently machined for electrical wiring, heat exchangers, and cooling systems.

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 implant

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.


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 

Ready to Start Your Project?

Use our convenient online Instant Quote tool today to receive immediate pricing and lead times tailored specifically for your CNC machining needs.

Instant Quote